CN116020507B - Photocatalyst, and preparation method and application thereof - Google Patents

Photocatalyst, and preparation method and application thereof Download PDF

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CN116020507B
CN116020507B CN202211601122.7A CN202211601122A CN116020507B CN 116020507 B CN116020507 B CN 116020507B CN 202211601122 A CN202211601122 A CN 202211601122A CN 116020507 B CN116020507 B CN 116020507B
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photocatalyst
noble metal
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CN116020507A (en
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彭超
王梓容
魏萍
陈一鸣
张月
黄志鹏
安万浩
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Wuyi University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

The invention relates to a photocatalyst, a preparation method and application thereof, comprising the following steps: (1) Ti is mixed with 3 C 2 T x Lye and H 2 O 2 The mass volume ratio of the solution is 200mg:60mL: mixing 0.4-1.3 mL; carrying out hydrothermal reaction on the mixed solution to obtain meta-titanate/Ti 3 C 2 T x The precipitate was collected by filtration and the prepared meta-titanate/Ti was washed with water 3 C 2 T x Washing to neutrality and drying; (2) Neutralizing the meta-titanate/Ti obtained in step (1) with an acid 3 C 2 T x Obtaining H 2 Ti 3 O 7 /Ti 3 C 2 T x Collecting solid by suction filtration, washing with water until the filtrate is neutral, freeze drying, and collecting dried H 2 Ti 3 O 7 /Ti 3 C 2 T x Heating under protective gas to obtain TiO 2 /Ti 3 C 2 O x The method comprises the steps of carrying out a first treatment on the surface of the (3) To the prepared TiO 2 /Ti 3 C 2 O x Adding acid or salt solution containing noble metal, and irradiating with 280-320W xenon lamp to obtain noble metal loaded TiO 2 /Ti 3 C 2 O x A base photocatalyst, i.e. the photocatalyst. The photocatalyst prepared by the invention has heterojunction, and high-dispersity noble metal particles are deposited under the photoinduction effect, so that the component of the photogenerated carriers is effectively improvedThe separation efficiency is obviously improved, and the photocatalyst is an excellent photocatalyst.

Description

Photocatalyst, and preparation method and application thereof
Technical Field
The invention belongs to the technical field of photocatalysis composite materials, and particularly relates to a photocatalyst, a preparation method and application thereof.
Background
Photocatalysis is considered to be a clean, green and efficient new technology, which can degrade pollutants and obtain sustainable energy. Semiconductor titanium dioxide (TiO) 2 ) Is the most commonly used photocatalyst and has the advantages of no toxicity, low price, stable chemical property and the like. However, tiO 2 The practical use of (c) is still hampered by its low electron-hole separation efficiency. TiO is mixed with 2 The heterojunction formed by coupling with transition metal or noble metal can effectively improve the separation efficiency of photon-generated carriers.
MXene is a generic name of Graphene-like two-dimensional transition metal carbide (nitride), and is a novel 2D transition metal carbide and nitride prepared by wet chemical etching. With Ti 3 C 2 T x Is represented by, wherein T x Represents a surface group including-F, -OH, and-O, etc. The surface groups of MXenes determine their work function (Φ), which can be as high as about 6eV when the MXene surface adsorbs-O, while TiO 2 About 4eV, -O-terminated Ti 3 C 2 O x Can be combined with TiO 2 A heterojunction is formed and serves as an excellent electron promoter to enhance photocatalytic activity. Based on Ti 3 C 2 T x And TiO 2 Has wide application prospect in the fields of electrochemistry, catalysis and the like, and has few researches and reports on Ti at present 3 C 2 T x Synthesis of TiO for precursors 2 @Ti 3 C 2 T x Complexes, e.g. ofPublication CN114471660A discloses a process for preparing monoatomically modified metal oxides/MXenes with photocatalytic hydrogen production of up to 1540. Mu. Mol g -1 h -1 However, the preparation process has a plurality of steps, photoelectrochemical etching is needed in the operation process, and an acidic etching solution is needed to be introduced into a reaction system, so that the subsequent treatment and the green chemistry concept are not facilitated.
In addition, noble metals can directly enhance the photocatalytic activity of the catalyst. In particular, nano-scale noble metal particles, have excellent electron conductivity. Publication "TiO 2 -Ti 3 C 2 Composites with Pt Decoration as Efficient Photocatalysts for Ethylene Oxidation under Near Infrared Light Irradiation ", discloses a process for preparing a catalyst by TiO 2 /Ti 3 C 2 And H is 2 PtCl 6 Synthesis of Pt-modified TiO 2 /Ti 3 C 2 The scheme of (2) synthesizing TiO 2 /Ti 3 C 2 Is etched by using HF aqueous solution, and on the surface of the MXees nano-sheet, abundant metal vacancies are common high-surface energy defects which can change coordination environment and surrounding electronic structure. Thus, these defects can act as anchor sites to trap and stabilize individual metal atoms. However, it is difficult to control the size of the supported noble metal nanoparticles and their uniformity because the particle size of the noble metal particles is increased due to the more negative fermi level of the noble metal and the formation of noble metal/semiconductor schottky junctions at the interface, once nucleated, the photo-generated electrons are more easily captured by the noble metal nanoparticles for further reduction.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a photocatalyst, a preparation method and application thereof, and the invention adopts simple hydrothermal and post-heat treatment processes to treat Ti 3 C 2 T x Upper in situ growth of TiO 2 At the same time Ti 3 C 2 T x The surface groups on the catalyst are uniformly adsorbed by-O at high temperature to finally form TiO 2 /Ti 3 C 2 O x A complex. And in situ TiO by photoinduction 2 /Ti 3 C 2 O x Depositing noble metal particles to obtain ultra-dispersed noble metal distribution with proper size to form noble metal loaded TiO 2 /Ti 3 C 2 O x And (3) a base photocatalyst so as to obtain higher photocatalytic hydrogen production activity.
In order to achieve the above object, the present invention provides the following technical solutions:
in a first aspect, the present invention provides a method for preparing a photocatalyst, comprising the steps of:
(1) Ti is mixed with 3 C 2 T x Lye and H 2 O 2 The solution is Ti in mass volume ratio 3 C 2 T x : alkali liquor: h 2 O 2 Solution = 200mg:60mL: mixing 0.4-1.3mL uniformly to obtain a mixed solution; carrying out hydrothermal reaction on the mixed solution to obtain meta-titanate/Ti 3 C 2 T x The precipitate was collected by filtration and the prepared meta-titanate/Ti was washed with water 3 C 2 T x Washing the composite material to neutrality and drying;
(2) Neutralizing the meta-titanate/Ti obtained in step (1) with an acid 3 C 2 T x Composite material to obtain H 2 Ti 3 O 7 /Ti 3 C 2 T x The method comprises the steps of carrying out a first treatment on the surface of the Collecting solid by suction filtration, washing with water until the filtrate is neutral, freeze drying, and collecting dried H 2 Ti 3 O 7 /Ti 3 C 2 T x Heating the composite material under the protection gas to obtain TiO 2 /Ti 3 C 2 O x ；
(3) TiO prepared in step (2) 2 /Ti 3 C 2 O x Adding acid or salt solution containing noble metal, and irradiating with 280-320W xenon lamp to obtain noble metal loaded TiO 2 /Ti 3 C 2 O x A base photocatalyst, i.e. the photocatalyst.
The invention uses simple hydrothermal and post-heat treatment process to treat Ti 3 C 2 T x Upper in situ growth of TiO 2 And annealing Ti by heat 3 C 2 T x The surface groups of (a) are unified as-O to form TiO 2 /Ti 3 C 2 O x And a heterojunction. Due to adsorption of MXene by-O (Ti 3 C 2 O x ) Has high work function and low fermi level, and can be combined with TiO 2 Schottky barriers and heterojunctions are formed that mediate the transfer of photogenerated electrons. Therefore, utilize Ti 3 C 2 O x As a mediator, tiO in the photo-deposition reduction process 2 Transfer of the electron portion of the surface to Ti 3 C 2 O x No electron aggregation occurs. In situ TiO by photoinduction 2 /Ti 3 C 2 O x Depositing noble metal particles to obtain ultra-dispersed noble metal distribution with proper size, and forming noble metal loaded TiO with high dispersity 2 /Ti 3 C 2 O x And (3) a base photocatalyst to obtain higher photocatalytic hydrogen production activity. Compared with the prior art, the method for preparing the photocatalyst by the hydrothermal and post-heat treatment process has the advantages of simple reaction system and low equipment requirement, does not need to introduce an organic solvent, adjust the pH value of the system or adjust the post-irradiation nucleation and then grow in the dark, and can ensure that noble metal particles with proper size and uniform distribution can be deposited on TiO in situ by keeping a low-temperature environment without a fluidized bed, liquid nitrogen and a freeze dryer 2 And (3) upper part.
As a preferred embodiment of the present invention, ti in step (1) 3 C 2 T x With lye and H 2 O 2 The mass volume ratio of the solution is Ti 3 C 2 T x : alkali liquor: h 2 O 2 Solution = 200mg:60mL:0.7-1.0mL; the lye comprises NaOH, KOH, mg (OH) 2 At least one of the above-mentioned alkali solutions OH - Is 10mol/L, H 2 O 2 H in solution 2 O 2 The concentration of (C) was 9.79mol/L.
As a preferred embodiment of the present invention, ti in step (1) 3 C 2 T x With lye and H 2 O 2 The mass volume ratio of the solution is 200mg:60mL:0.7-1.0mL. TiO prepared by using the proportion 2 /Ti 3 C 2 O x With an optimal number of heterojunctions. In addition, the NaOH solution is cooledCan not add H until the room temperature 2 O 2 Solution to avoid H 2 O 2 The solution is volatilized by heating.
The scheme is realized by changing H 2 O 2 The addition amount of Ti in the synthetic material is controlled 3 C 2 T x And TiO 2 To regulate the number of heterojunctions in the composite. Ti is added in the subsequent thermal annealing process 3 C 2 T x The surface groups of (a) are unified as-O adsorption groups. TiO (titanium dioxide) 2 With Ti 3 C 2 O x The heterojunction formed between the two can lead photo-generated electron-hole pairs to be formed in TiO 2 And Ti is 3 C 2 O x The heterojunction interface of the (C) is migrated, the separation efficiency of photo-generated electron-hole pairs is improved, the recombination rate of photo-generated carriers is reduced, and the photocatalysis quantum efficiency is improved, so that the TiO of the composite material is greatly improved 2 /Ti 3 C 2 O x Is a component of the photocatalytic activity of the catalyst.
As a preferred embodiment of the present invention, in the step (1), the hydrothermal reaction is carried out at a temperature of 160 to 200℃for 20 to 28 hours.
As a more preferred embodiment of the present invention, in the step (1), the temperature of the hydrothermal reaction is 180℃and the time is 24 hours.
The hydrothermal method adopted in the invention has the advantages of simple experimental conditions, easy control of reaction conditions (such as temperature, time, pH and the like), low cost and easy operation; secondly, pure water is used as a solvent, so that the precursor can be better dispersed. In the invention, the improvement of the activity from 160 ℃ to 200 ℃ can be attributed to the gradual change of the crystallization performance of the material in the hydrothermal process, and the effective separation of electron hole pairs is obtained. However, the hydrothermal temperature continues to rise and the photocatalytic activity decreases, probably because the hydrothermal temperature is too high, the materials tend to agglomerate together, the light absorption of the catalyst decreases and the photo-generated charge separation capacity decreases. However, for hydrothermal time, the hydrothermal time is too long, which is unfavorable for the formation of perfect crystals, and adverse phenomena such as sphere collapse, grain aggregation and the like may exist. Therefore, considering the problems of catalytic performance, experimental procedures, energy conservation and the like, the hydrothermal reaction temperature is preferably 180 ℃ and the reaction time is preferably 24 hours.
As a preferred embodiment of the invention, in step (2), the acid is 0.1mol/L HCl solution.
In a preferred embodiment of the present invention, in step (2), the shielding gas is nitrogen, helium or argon.
In a more preferred embodiment of the present invention, in step (2), the shielding gas is nitrogen.
As a preferred embodiment of the present invention, in the step (2), the heating condition is maintained at 500 to 700℃for 4 hours.
As a more preferred embodiment of the present invention, in the step (2), the heating condition is maintained at 600℃for 4 hours.
High temperature calcination in a protective gas atmosphere can enable Ti to be 3 C 2 T x Upper in situ growth of TiO 2 At the same time Ti 3 C 2 T x The surface groups on the catalyst are uniformly adsorbed by-O at high temperature to finally form TiO 2 /Ti 3 C 2 O x A complex. This is beneficial for TiO 2 /Ti 3 C 2 O x The heterojunction is formed through the Schottky barrier, so that the recombination rate of photo-generated electrons and holes can be effectively reduced, the hydrogen production capacity of the catalyst for photo-catalytic pyrolysis of water is improved, and the application of the MXene material in the field of photocatalysis is widened.
In a preferred embodiment of the present invention, in the step (3), the noble metal is one of gold, silver and platinum, the acid solution containing the noble metal is chloroplatinic acid or chloroauric acid, and the salt in the salt solution containing the noble metal is silver nitrate.
In a more preferred embodiment of the present invention, the noble metal is one of platinum and gold, and the acid solution containing the noble metal is one of chloroplatinic acid and chloroauric acid. The catalysts obtained are respectively marked as PM-zPt-TiO 2 /Ti 3 C 2 O x -y、PM-zAu-TiO 2 /Ti 3 C 2 O x Y, where z is the loading of Pt, au. The TiO loaded by different noble metals can be obtained by replacing chloroplatinic acid and chloroauric acid aqueous solution with other noble metal aqueous solution 2 /Ti 3 C 2 O x -y material.
As a preferred embodiment of the present invention, in step (3), the noble metal loading is 0.05 to 2.0wt%.
TiO 2 Nano-noble metal deposition on the surface can significantly improve the photocatalytic efficiency because the interfacial electrons transfer from the semiconductor to the metal deposition more rapidly. To increase photocatalytic activity, noble metals require optimal loading values and uniform distribution in addition to being deposited on semiconductors in proper sizes. Under high concentration metal loading, the metals come into contact and overlap with each other, thereby shrinking the metal/TiO 2 And the interface also reduces the efficiency of interface electron transfer. The deposited metal can act as a barrier to photon absorption, enhancing recombination at higher metal concentrations, and also activating trapped electrons.
As a preferred embodiment of the present invention, the irradiation source in step (3) is a 300W xenon lamp.
The electrodeposition method is the simplest method for supporting noble metals. Under the irradiation of the xenon lamp, the semiconductor material is excited to generate photo-generated electrons (e - ) And corresponding holes (h) + ) Both of which are temporarily present on the surface of the material. Research has shown that photo-generated electrons (e - ) May be reacted with noble metal ions in the reducing solution resulting in situ deposition of the noble metal.
In a second aspect, the present invention provides a photocatalyst.
In a third aspect, the invention also claims the use of said photocatalyst in photocatalytic hydrogen production.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention uses simple hydrothermal and post-heat treatment process to treat Ti 3 C 2 T x Upper in situ growth of TiO 2 At the same time make Ti 3 C 2 T x The upper surface groups are unified as-O groups, and finally the TiO is prepared 2 /Ti 3 C 2 O x . In the process, H is added 2 O 2 Volume-adjusting TiO 2 And TiO 2 /Ti 3 C 2 O x Heterogeneous materialJunction number, tiO for direct synthesis of oxygen adsorbing group 2 /Ti 3 C 2 O x For photocatalytic reactions.
(2) The invention can finish the super-dispersion of the noble metal nano particles under the light induction effect without introducing organic solvent, adjusting the pH value of the system or adjusting the irradiation nucleation after the adjustment, then growing in the dark, maintaining the low-temperature environment by virtue of a fluidized bed, liquid nitrogen and a freeze dryer, and the like.
Drawings
FIG. 1 is a diagram of TiO prepared in examples 1-4 and comparative examples 1-2 2 /Ti 3 C 2 O x -y、A-TiO 2 With TiO 2 -correlation profile of 1.0. FIG. 1 (a) TiO 2 /Ti 3 C 2 O x -y and (b) A-TiO 2 、TiO 2 -XRD pattern of 1.0, (c) TiO 2 /Ti 3 C 2 O x -y and (d) A-TiO 2 、TiO 2 -FT-IR spectrum of 1.0; tiO (titanium dioxide) 2 /Ti 3 C 2 O x -y (e) raman spectrum, (f) uv-vis diffuse reflectance spectrum, (g) N 2 Adsorption-desorption isotherms and (h) pore distribution curves.
FIG. 2 is a diagram of TiO as prepared in examples 1-4 2 /Ti 3 C 2 O x -SEM image of y. FIG. 2 (a) TiO 2 /Ti 3 C 2 O x -0.4，(b)TiO 2 /Ti 3 C 2 O x -0.7，(c)TiO 2 /Ti 3 C 2 O x -1.0 and (d) TiO 2 /Ti 3 C 2 O x -SEM image of 1.3.
FIG. 3 is a TiO film prepared in example 3 2 /Ti 3 C 2 O x -1.0 of (a) a TEM image, (b-d) an HRTEM image, (e) an EDX element map of HAADF and Ti, O, C elements.
FIG. 4 is a PM-0.2Pt-TiO prepared in example 6 2 /Ti 3 C 2 O x -1.0 of (a) SEM images, (b) TEM images, (c) SAED images, (d-g) HRTEM images, (h) EDX element mapping of HAADF and Ti, C, O, pt elements.
FIG. 5 is a schematic diagram of IM-0.2Pt-TiO prepared in comparative example 6 2 /Ti 3 C 2 O x -1.0 of (a) SEM images, (b) TEM images, (c) SAED images, (d) HRTEM images, (e) EDX element mapping of HAADF and Ti, C, O, pt elements.
FIG. 6 is a PM-0.2Pt-TiO prepared in comparative example 3 2 -1.0, (a) SEM images, (b) TEM images, (c) SAED images, (d) HRTEM images, (e) EDX element mapping of HAADF and Ti, O, pt elements.
FIG. 7 is a distribution diagram of the particle size of Pt supported in each of the catalysts prepared in example 6, comparative example 6 and comparative example 3, (a, b) PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、(c,d)IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and (e, f) PM-0.2Pt-TiO 2 -Pt particle size distribution profile of 1.0.
FIG. 8 is Ti 3 C 2 T x And TiO prepared in example 3 2 /Ti 3 C 2 O x -XPS spectra of (a) C1s, (b) Ti2p, (C) O1 s and (d) F1 s of the 1.0 catalyst.
FIG. 9 shows XPS spectra of the catalysts prepared in example 6, comparative example 6 and comparative example 3, respectively. (a) PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Pt-TiO 2 /Ti 3 C 2 O x C1s spectrum of-1.0 and PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 -1.0 of (b) Ti2p, (c) O1 s and (d) Pt 4f spectra.
FIG. 10 is a comparison of photocatalytic hydrogen production activities for each of the catalysts prepared in examples 1-14 and comparative examples 1-8. (a) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -comparison of the evolution of photocatalytic hydrogen production from methanol/water solution of y; (b) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -comparison of the methanol/water solution photocatalytic hydrogen production rate of y; (c) PM-0.2Pt-TiO 2 -1.0 and PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -comparison of the evolution of photocatalytic hydrogen production from methanol/water solution of y; (d) IM-0.2Pt-TiO 2 -1.0 and IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -comparison of the evolution of photocatalytic hydrogen production from methanol/water solution of y; (e) PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -y、PM-0.2Pt-TiO 2 -1.0 and IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -y、IM-0.2Pt-TiO 2 -1.0 methanol/water solution photocatalytic hydrogen production rate comparison; (f) PM-zPt-TiO 2 /Ti 3 C 2 O x -methanol/water solution photocatalytic hydrogen production evolution comparison of 1.0; (g) PM-zPt-TiO 2 /Ti 3 C 2 O x -1.0 methanol/water solution photocatalytic hydrogen production rate comparison; tiO (titanium dioxide) 2 /Ti 3 C 2 O x -1.0 and PM-1.0Pt-TiO 2 /Ti 3 C 2 O x -1.0 of (h) wavelength dependent quantum yield and (i) photocatalytic hydrogen production reaction cycle stability.
FIG. 11 is a comparison of photocatalytic hydrogen production activity for each of the catalysts prepared in comparative examples 9-16. (a) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -1.0、TiO 2 -1.0、PM-0.2Au-TiO 2 -1.0、PM-0.2Au-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Au-TiO 2 /Ti 3 C 2 O x -methanol/water solution photocatalytic hydrogen production evolution comparison of 1.0; (b) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -1.0、TiO 2 -1.0、PM-0.2Au-TiO 2 -1.0、PM-0.2Au-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Au-TiO 2 /Ti 3 C 2 O x -1.0 methanol/water solution photocatalytic hydrogen production rate comparison; (c) Comparative examples 9-16 prepared methanol/water solution photocatalytic hydrogen production evolution comparison; (d) Comparative examples 9-16 prepared methanol/water solutions were compared for photocatalytic hydrogen production evolution.
FIG. 12 is a comparison of photocatalytic hydrogen production activity for each of the catalysts prepared in comparative examples 17-23. (a) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -1.0、TiO 2 -1.0、PM-0.2Ag-TiO 2 -1.0、PM-0.2Ag-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Ag-TiO 2 /Ti 3 C 2 O x 1.0 photocatalytic preparation of methanol/Water solutionHydrogen evolution comparison; (b) TiO (titanium dioxide) 2 /Ti 3 C 2 O x -1.0、TiO 2 -1.0、PM-0.2Ag-TiO 2 -1.0、PM-0.2Ag-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Ag-TiO 2 /Ti 3 C 2 O x -1.0 methanol/water solution photocatalytic hydrogen production rate comparison; (c) Comparative examples 17-23 prepared methanol/water solution photocatalytic hydrogen production evolution comparison; (d) Comparative examples 17-23 were prepared to compare the evolution of photocatalytic hydrogen production from methanol/water solutions.
FIGS. 13 (a) and (d) are Ti 3 C 2 O x And A-TiO 2 (b) and (e) are Ti 3 C 2 O x And A-TiO 2 And (c) and (f) are Ti 3 C 2 O x And A-TiO 2 Is provided.
FIG. 14 (a) A-TiO 2 And (b) TiO 2 /Ti 3 C 2 O x -Mott-Schottky graph of 1.0, (c) A-TiO 2 And TiO 2 /Ti 3 C 2 O x The inset in (c) is A-TiO 2 And TiO 2 /Ti 3 C 2 O x -a DRUV-vis spectrum of 1.0.
FIG. 15 shows TiO according to the invention 2 /Ti 3 C 2 O x Photocatalytic mechanism of the catalyst.
Detailed Description
For a better description of the objects, technical solutions and advantages of the present invention, the present invention will be further described with reference to the following specific examples.
The starting materials used in the examples below were all commercially available.
Example 1
One embodiment of the photocatalyst and the preparation method thereof of the invention is the TiO 2 /Ti 3 C 2 O x The preparation method of-0.4 is as follows: 60mL of 10mol/LNaOH and 200mg of Ti were each added to 1 150ml Erlenmeyer flask 3 C 2 T x After dissolving the powder and cooling to room temperature, 0.4mL H was added to each flask 2 O 2 Solution. The solution was transferred to a teflon lined stainless steel reactor for a 24h hydrothermal reaction at 180 ℃. The suspension was collected by filtration and the prepared Na was purified by distilled water 2 Ti 3 O 7 /Ti 3 C 2 T x And washing the composite material to neutrality and drying. Then neutralizing the above material with 0.1mol/L HCl solution to obtain H 2 Ti 3 O 7 /Ti 3 C 2 T x The solid was collected by suction filtration and lyophilized after washing with deionized water until the filtrate was neutral. Finally, H 2 Ti 3 O 7 /Ti 3 C 2 T x The composite material is kept for 4 hours in nitrogen atmosphere at 600 ℃ to obtain TiO 2 /Ti 3 C 2 O x -0.4。
Example 2
One embodiment of the photocatalyst and the preparation method thereof of the invention is the TiO 2 /Ti 3 C 2 O x -0.7 differs from example 1 in that H is added to the flask 2 O 2 The volume of the solution is 0.7mL, the rest conditions are the same, and finally the TiO is prepared 2 /Ti 3 C 2 O x -0.7。
Example 3
One embodiment of the photocatalyst and the preparation method thereof of the invention is the TiO 2 /Ti 3 C 2 O x -1.0 differs from example 1 in that H is added to the flask 2 O 2 The volume of the solution is 1.0mL, the rest conditions are the same, and finally the TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 4
One embodiment of the photocatalyst and the preparation method thereof of the invention is the TiO 2 /Ti 3 C 2 O x -1.3 differs from example 1 in that H is added to the flask 2 O 2 The volume of the solution is 1.3mL, the rest conditions are the same, and finally the TiO is prepared 2 /Ti 3 C 2 O x -1.3。
Example 5
The photocatalyst of the present inventionAn embodiment of the preparation method of the PM-0.1Pt-TiO according to the embodiment 2 /Ti 3 C 2 O x The preparation method of-1.0 is as follows: 10mg of TiO prepared in example 3 2 /Ti 3 C 2 O x 1.0 is sonicated in 100mL of 20% aqueous methanol. 5 mu L of H was added to the reactor 2 PtCl 6 ·6H 2 O aqueous solution, the irradiation light source is a 300W xenon lamp, so that TiO 2 /Ti 3 C 2 O x -Pt loading of 1.0 was 0.1wt%. The catalyst obtained was labeled PM-0.1Pt-TiO 2 /Ti 3 C 2 O x -1.0, wherein 0.1 is the loading of Pt.
Example 6
One embodiment of the photocatalyst and the preparation method thereof is PM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from example 5 in that H is fed into the reactor 2 PtCl 6 ·6H 2 The O aqueous solution is 10 mu L, the rest conditions are the same, and finally PM-0.2Pt-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 7
One embodiment of the photocatalyst and the preparation method thereof is PM-0.5Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from example 5 in that H is fed into the reactor 2 PtCl 6 ·6H 2 The O aqueous solution is 25 mu L, the rest conditions are the same, and finally PM-0.5Pt-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 8
One embodiment of the photocatalyst and the preparation method thereof is PM-1.0Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from example 5 in that H is fed into the reactor 2 PtCl 6 ·6H 2 The O aqueous solution is 50 mu L, the rest conditions are the same, and finally PM-1.0Pt-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 9
One embodiment of the photocatalyst and the preparation method thereof is PM-1.5Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from example 5 in that H is fed into the reactor 2 PtCl 6 ·6H 2 The O aqueous solution is 75 mu L, the rest conditions are the same, and finally PM-1.5Pt-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 10
One embodiment of the photocatalyst and the preparation method thereof is PM-2.0Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from example 5 in that H is fed into the reactor 2 PtCl 6 ·6H 2 The O aqueous solution is 100 mu L, the rest conditions are the same, and finally PM-2.0Pt-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Example 11
One embodiment of the photocatalyst and the preparation method thereof is PM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-0.4 differs from example 6 in that 10mg of the TiO from example 1 are added as catalyst 2 /Ti 3 C 2 O x -0.4, the catalyst obtained is marked PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -0.4, wherein 0.2 is the Pt loading.
Example 12
One embodiment of the photocatalyst and the preparation method thereof is PM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-0.7 differs from example 6 in that 10mg of the TiO from example 2 are added 2 /Ti 3 C 2 O x -0.7, the catalyst obtained is marked PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -0.7。
Example 13
The photocatalyst and the preparation thereofOne embodiment of the method is PM-0.2Pt-TiO as described in this embodiment 2 /Ti 3 C 2 O x The process for preparing 1.3 differs from example 6 in that 10mg of the TiO prepared in example 4 are added as catalyst 2 /Ti 3 C 2 O x -1.3 labelling the catalyst obtained as PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.3。
Comparative example 1
A comparative example of the photocatalyst and the preparation method thereof of the present invention, the A-TiO of this example 2 The preparation method of (2) comprises the following steps: 100mg of Ti 3 C 2 T x With 15mL of 1mol/L HCl and 0.615g of NaBF 4 Hydrothermal reaction at 180 ℃ for 36h to obtain anatase type TiO 2 Labeled A-TiO 2 。
Comparative example 2
A comparative example of the photocatalyst and the preparation method thereof of the present invention, the TiO of this example 2 The preparation method of-1.0 is as follows: 200mg of P25 are added to 60mL of 10mol/L NaOH and 1.0mL of H 2 O 2 In solution, the hydrothermal reaction was then carried out at 180℃for 24 hours. The prepared complex was washed to neutrality and dried. The powder was then neutralized with 0.1mol/L HCl solution and washed until the filtrate became neutral. After freeze-drying, the mixture was kept at 600℃for 4 hours in a nitrogen atmosphere to obtain TiO 2 -1.0。
Comparative example 3
One embodiment of the photocatalyst and the preparation method thereof is PM-0.2Pt-TiO 2 The process for preparing-1.0 differs from example 6 in that 10mg of TiO from comparative example 2 are added as catalyst 2 -1.0, the catalyst obtained is marked PM-0.2Pt-TiO 2 -1.0。
Comparative example 4
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Pt-TiO 2 /Ti 3 C 2 O x The preparation method of-0.4 is as follows: 10mg of TiO prepared in example 1 2 /Ti 3 C 2 O x -0.4 immersion in 10. Mu.L of H 2 PtCl 6 ·6H 2 In the O aqueous solution, pt was supported at 0.2wt%. And carrying out ultrasonic treatment on the mixed solution and then drying. The powder was dispersed in 10mL of deionized water and 1mg NaBH was used 4 And (5) reduction. Standing for a period of time, washing with water, suction filtering, and vacuum drying again to obtain Pt-loaded TiO prepared by impregnation method 2 /Ti 3 C 2 O x -0.4, i.e. IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -0.4。
Comparative example 5
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-0.7 differs from comparative example 4 in that the catalyst added is the TiO prepared in example 2 2 /Ti 3 C 2 O x -0.7, the rest conditions being the same, obtaining IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -0.7。
Comparative example 6
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 4 in that the catalyst added is the TiO prepared in example 3 2 /Ti 3 C 2 O x -1.0, the remaining conditions being the same, obtaining IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0。
Comparative example 7
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Pt-TiO 2 /Ti 3 C 2 O x The process for preparing 1.3 differs from comparative example 4 in that the catalyst added is the TiO prepared in example 4 2 /Ti 3 C 2 O x -1.3, the remaining conditions being the same, obtaining IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.3。
Comparative example 8
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Pt-TiO 2 The preparation process of (2) differs from comparative example 4 in that the catalyst added is 10mg of TiO prepared in comparative example 2 2 -1.0, the remaining conditions being the same, obtaining IM-0.2Pt-TiO 2 -1.0。
Comparative example 9
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.1Au-TiO 2 /Ti 3 C 2 O x The preparation method of-1.0 is as follows: 10mg of TiO prepared in example 3 2 /Ti 3 C 2 O x 1.0 is sonicated in 100mL of 20% aqueous methanol. 5.1. Mu.L of HAuCl was added to the reactor 4 ·3H 2 O aqueous solution, the irradiation light source is a 300W xenon lamp, so that TiO 2 /Ti 3 C 2 O x -1.0Au loading was 0.1wt%. The catalyst obtained was labeled PM-0.1Au-TiO 2 /Ti 3 C 2 O x -1.0, wherein 0.1 is the loading of Au.
Comparative example 10
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.2Au-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 9 in that HAuCl is fed into the reactor 4 ·3H 2 The O aqueous solution is 10.2 mu L, the rest conditions are the same, and finally PM-0.2Au-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 11
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.5Au-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 9 in that HAuCl is fed into the reactor 4 ·3H 2 The O aqueous solution is 25.5 mu L, the rest conditions are the same, and finally PM-0.5Au-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 12
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-1.0Au-TiO 2 /Ti 3 C 2 O x -1.0The preparation process differs from comparative example 9 in that HAuCl was fed into the reactor 4 ·3H 2 The O aqueous solution is 51.0 mu L, the rest conditions are the same, and finally PM-1.0Au-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 13
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-1.5Au-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 9 in that HAuCl is fed into the reactor 4 ·3H 2 The aqueous solution of O is 76.5 mu L, the rest conditions are the same, and finally PM-1.5Au-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 14
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-2.0Au-TiO as described in this comparative example 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 9 in that HAuCl is fed into the reactor 4 ·3H 2 The O aqueous solution is 102.0 mu L, the rest conditions are the same, and finally PM-2.0Au-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 15
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.2Au-TiO 2 The process for preparing-1.0 differs from comparative example 9 in that the catalyst added is TiO prepared in comparative example 2 2 -1.0, the rest conditions are the same, finally PM-2.0Au-TiO is prepared 2 -1.0。
Comparative example 16
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Au-TiO 2 /Ti 3 C 2 O x The preparation method of-1.0 is as follows: 10mg of TiO prepared in example 3 2 /Ti 3 C 2 O x 1.0 immersion in 10. Mu.L of HAuCl 4 ·3H 2 In the O aqueous solution, the Au loading was made to be 0.2wt%. And carrying out ultrasonic treatment on the mixed solution and then drying. The powder was dispersed in 10mL of deionized water and 1mg NaBH was used 4 And (5) reduction. Standing for a period of time, washing with water, suction filtering, and vacuum drying again to obtain Au-loaded TiO prepared by the impregnation method 2 /Ti 3 C 2 O x -1.0, i.e. IM-0.2Au-TiO 2 /Ti 3 C 2 O x -1.0。
Comparative example 17
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.05Ag-TiO 2 /Ti 3 C 2 O x The preparation method of-1.0 is as follows: 10mg of TiO prepared in example 3 2 /Ti 3 C 2 O x 1.0 is sonicated in 100mL of 20% aqueous methanol. Adding 4.63 mu L of AgNO into the reactor 3 Aqueous solution, irradiation light source is 300W xenon lamp, so that TiO 2 /Ti 3 C 2 O x -1.0 Ag loading was 0.05wt%. The catalyst obtained was labeled PM-0.05Ag-TiO 2 /Ti 3 C 2 O x -1.0, wherein 0.05 is the loading of Ag.
Comparative example 18
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.1Ag-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 17 in that AgNO is fed into the reactor 3 The aqueous solution is 9.25 mu L, the rest conditions are the same, and finally PM-0.1Ag-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 19
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.2Ag-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 17 in that AgNO is fed into the reactor 3 The aqueous solution is 18.5 mu L, the rest conditions are the same, and finally PM-0.2Ag-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 20
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.5Ag-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 17 in that AgNO is fed into the reactor 3 The aqueous solution is 46.3 mu L, the rest conditions are the same, and finally PM-0.5Ag-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 21
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-1.0Ag-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 17 in that AgNO is fed into the reactor 3 92.5 mu L of aqueous solution and the rest conditions are the same, finally PM-1.0Ag-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Comparative example 22
A comparative example of the photocatalyst and the preparation method thereof of the invention is PM-0.2Ag-TiO 2 The process for preparing-1.0 differs from comparative example 17 in that the catalyst added is TiO prepared in comparative example 2 2 -1.0, the rest conditions are the same, finally PM-0.2Ag-TiO is prepared 2 -1.0。
Comparative example 23
A comparative example of the photocatalyst and the preparation method thereof of the invention is IM-0.2Ag-TiO 2 /Ti 3 C 2 O x The process for preparing-1.0 differs from comparative example 16 in that the metal salt solution added is AgNO 3 The water solution and other conditions are the same, and finally the IM-0.2Ag-TiO is prepared 2 /Ti 3 C 2 O x -1.0。
Test example 1
H 2 O 2 Effect of the amount of use and heterojunction on the photocatalytic hydrogen production efficiency of the catalyst
An automatic online trace gas analysis system was used to conduct the photocatalytic hydrogen production experiments. Ti used in 10mg of the photocatalyst prepared in examples 1 to 4 and comparative examples 1 to 2 above was used 3 C 2 T x Ultrasonic dispersion in 100mL of 20% aqueous methanol. Before the reaction starts, the system is evacuated of dissolved oxygen with a vacuum pump. The irradiation light source is a 300W xenon lamp. Using an on-line gas chromatographThe thermal conductivity detector measures hydrogen gas generated once per hour, and each catalyst performs five-hour photocatalytic hydrogen production experiments.
The photocatalytic hydrogen production performance is shown in fig. 10 (a) (b). Ti alone 3 C 2 O x Almost no catalytic activity (5.8. Mu. Mol g) -1 h -1 ) This is due to its metal-like nature. At the same time, does not contain Ti 3 C 2 O x Anatase TiO of (2) 2 (A-TiO 2 ) And TiO 2 -1.0 (P25 derived TiO) 2 Nanorods) are low in hydrogen production activity (35.8 and 81.6. Mu. Mol g, respectively -1 h -1 ). This illustrates Ti alone 3 C 2 O x With TiO 2 Hardly plays a role in catalyzing hydrogen production, but when the two are combined through a heterojunction structure, tiO is found 2 /Ti 3 C 2 O x The catalytic performance of the composite material is obviously improved, and TiO 2 /Ti 3 C 2 O x Photocatalytic hydrogen production performance of composite material and H in synthesis process 2 O 2 Is closely related to the amount of added(s). TiO (titanium dioxide) 2 /Ti 3 C 2 O x -0.4 hydrogen production in 5h of 566. Mu. Mol g -1 (113.2μmol g -1 h -1 ). When H is 2 O 2 When the amount of the additive was increased from 0.7mL to 1.0mL, the hydrogen production amount was increased to 1289 and 1734. Mu. Mol g in 5 hours, respectively -1 (FIG. 10 a). To further improve H 2 O 2 At the same time of adding quantity of TiO 2 /Ti 3 C 2 O x -1.3 hydrogen production was reduced to 1009. Mu. Mol g -1 (201.8μmol g -1 h -1 ). This can be explained by the fact that the stronger the oxidation level, the TiO 2 The faster the nanowhisker formation rate, which results in a relatively low H 2 O 2 Under the volume, tiO 2 /Ti 3 C 2 O x The number of heterojunctions increases. However, due to Ti 3 C 2 T x Total loss of MXene, H 2 O 2 The heterojunction in the composite material is reduced when excess. Wherein, the best TiO 2 /Ti 3 C 2 O x -hydrogen production rate of 1.0 reaches 346.8 mu mol g -1 h -1 Is A-TiO 2 And TiO 2 -9.7 and 4.3 times 1.0.
Test example 2
Influence of Pt loading on photocatalytic Hydrogen production efficiency of catalyst
The test example differs from test example 1 in that the photocatalyst used was the catalyst prepared in examples 5 to 10, the rest of the conditions were the same, a catalytic hydrogen production experiment was performed, and in addition, the TiO with the best activity was used 2 /Ti 3 C 2 O x -1.0 and PM-1.0Pt-TiO 2 /Ti 3 C 2 O x -1.0 five photocatalytic hydrogen production cycles were performed to determine its stability and to obtain by experiment and calculation Apparent Quantum Efficiencies (AQEs) at 313, 350 and 380nm incident monochromatic wavelengths.
As shown in fig. 10 (f) (g). It can be found that PM-zPt-TiO 2 /Ti 3 C 2 O x The hydrogen production of 1.0 increases and then decreases with increasing Pt loading. At a Pt loading of 0.1%, the hydrogen production in 5 hours was 58.0mmol g -1 (11.6mmol g -1 h -1 ). When the Pt loading increased from 0.5% to 1.0%, the hydrogen yield increased to 77.4 and 88.0mmol g, respectively, over 5h -1 (15.5 and 17.6mmol g) -1 h -1 ) (FIG. 10 f). PM-1.5Pt-TiO while further increasing Pt loading 2 /Ti 3 C 2 O x -1.0 and PM-2.0Pt-TiO 2 /Ti 3 C 2 O x -1.0 hydrogen production was reduced to 67.3 and 62.9mmol g -1 (13.5 and 12.6mmol g) -1 h -1 ). This can be explained by the fact that at low Pt loading densities (0.1-0.5%), pt is associated with TiO 2 /Ti 3 C 2 O x The contact surface is not large enough to absorb light effectively, and thus the photocatalytic activity is lowered. The activity is also reduced at higher Pt loading densities because the metallic coatings begin to contact and overlap each other, thereby reducing the efficiency of interfacial electron transfer. In addition, the deposited Pt acts as a barrier to photon absorption, enhancing recombination at higher metal concentrations, and also activating the trapped electrons. Therefore, the optimal Pt loading contributes to light absorption and has a high photo-generated carrier separation efficiency.
For TiO 2 /Ti 3 C 2 O x -1.0 and PM-1.0Pt-TiO 2 /Ti 3 C 2 O x -1.0 an apparent quantum yield experiment was performed as shown in fig. 10 (h). TiO (titanium dioxide) 2 /Ti 3 C 2 O x Apparent quantum yields at 313, 350 and 380nm of 1.0 were 7.67%, 2.61% and 1.08%. When 1.0% Pt is used for TiO 2 /Ti 3 C 2 O x 1.0 with apparent quantum yields of 41.2%, 55.6% and 8.2% at 313, 350 and 380nm when subjected to in situ photo-deposition. In TiO 2 /Ti 3 C 2 O x -1.0 and PM-1.0Pt-TiO 2 /Ti 3 C 2 O x In the five-cycle experiment of-1.0, the photocatalytic hydrogen production performance hardly changed (fig. 10 i), and the two photocatalysts are proved to have good stability and reusability.
Test example 3
Pt loading mode and Ti 3 C 2 O x Influence on the photocatalytic Hydrogen production efficiency of the catalyst
The difference between the present test example and test example 1 is that the photocatalysts used are examples 11 to 14 and comparative examples 3 to 8, respectively, were deposited in situ under light induction and supported with 0.2% pt using an immersion method, and the photocatalytic hydrogen production performance is shown in fig. 10 (c-e). After loading Pt, tiO 2 /Ti 3 C 2 O x The hydrogen production law of y is the same as when Pt is not loaded. PM-0.2Pt-TiO 2 /Ti 3 C 2 O x 0.4 hydrogen production in 5h up to 6.6mmol g -1 h -1 ，IM-0.2Pt-TiO 2 /Ti 3 C 2 O x 0.4 hydrogen production in 5h up to 2.2mmol g -1 h -1 19.4 times that of the case where no Pt was deposited. When H is 2 O 2 When the addition amount of (2) is 0.7, 1.0 and 1.3mL, the hydrogen yield reaches 9.1, 13.2 and 8.2mmol g after the 0.2 percent Pt is loaded by the photo-deposition method -1 h -1 35.3, 38.1, 40.7 times before 0.2% pt was deposited. While the impregnation method is used for loading 0.2 percent Pt, and the hydrogen production amount is only 3.1, 4.4 and 3.2mmol g -1 h -1 . This demonstrates that the photo-deposition process carried Pt has, in contrast to the immersion processHigher photocatalytic activity. Meanwhile, PM-0.2Pt-TiO 2 /Ti 3 C 2 O x The hydrogen yield of 1.0 is PM-0.2Pt-TiO 2 -1.0(5.8mmol g -1 h -1 ) 2.3 times of (3). This suggests that ultra-dispersed Pt nanoparticles of suitable size, photoinduction and Ti were supported 3 C 2 O x Is indispensable for the mediation of the (C). This is because of Ti 3 C 2 O x Mediating the action of photo-generated electrons, conducting TiO 2 The photo-generated electrons on the surface are not accumulated on the surface, so that Pt is not accumulated on TiO 2 The surface aggregation load, namely, the high-dispersity noble metal particles can be obtained by deposition under the light induction effect.
Test example 4
Au loading mode and Ti 3 C 2 O x Influence on the photocatalytic Hydrogen production efficiency of the catalyst
The difference between the present test example and test example 3 is that the photocatalysts used are comparative examples 9 to 16, respectively, 0.1% -2.0% of Au is deposited and supported in situ under the light induction and 0.2% of Au is supported by using the dipping method, and the photocatalytic hydrogen production performance is shown in fig. 11 (a-d). Wherein, tiO is prepared by a photo-deposition method 2 /Ti 3 C 2 O x After loading 0.2% Au on-1.0, the photocatalytic hydrogen evolution activity reached 6.7mmol g -1 h -1 This is achieved by impregnating TiO 2 /Ti 3 C 2 O x -1.0 is loaded with 5.2 times of 0.2 percent of Au photocatalysis hydrogen evolution activity, which is carried on TiO by a photo-deposition method 2 2.7 times the photocatalytic hydrogen evolution activity of 0.2% Au was supported on 1.0 (FIG. 11a, b). This shows that Au loading and Pt loading show similar carrier effects, i.e. under photo-induction, by Ti 3 C 2 O x The noble metal particles with high dispersity can be obtained by mediating the transfer action of photo-generated electrons.
Further optimizing the photo-deposition method to prepare Au-loaded TiO 2 /Ti 3 C 2 O x -1.0. It can be found that PM-zAu-TiO 2 /Ti 3 C 2 O x The hydrogen production of 1.0 increases and then decreases with increasing Au loading. When the Au loading is 0.1%, the photocatalytic hydrogen evolution activity is 5.4mmol g -1 h -1 . When the Au loading increased from 0.5% to 1.0%, the photocatalytic hydrogen evolution activity increased to 8.7 and 14.1mmol g, respectively -1 h -1 (FIG. 11 d). PM-1.5Au-TiO while further increasing Au loading 2 /Ti 3 C 2 O x -1.0 and PM-2.0Au-TiO 2 /Ti 3 C 2 O x The hydrogen production of 1.0 was reduced to 11.7 and 7.5mmol g -1 h -1 . This is because at low Au loading densities (0.1-0.5%), au is present with TiO 2 /Ti 3 C 2 O x The contact surface of-1.0 is not large enough to absorb light efficiently, and thus the photocatalytic activity is reduced. And the metal plating layers start to contact and overlap with each other at a higher Au loading density, thereby reducing the efficiency of interfacial electron transfer.
Test example 5
Ag loading mode and Ti 3 C 2 O x Influence on the photocatalytic Hydrogen production efficiency of the catalyst
The difference between the present test example and test example 3 is that the photocatalysts used are comparative examples 17 to 23, respectively, and the photocatalytic hydrogen production performance is shown in fig. 12 (a-d) by carrying 0.05% -1.0% ag by in-situ deposition under photo-induction and 0.2% ag by dipping. Wherein, tiO is prepared by a photo-deposition method 2 /Ti 3 C 2 O x After loading 0.2% Ag on-1.0, the photocatalytic hydrogen evolution activity reached 5.4mmol g -1 h -1 This is achieved by impregnating TiO 2 /Ti 3 C 2 O x -1.0 is loaded with 9 times of the photocatalytic hydrogen evolution activity of 0.2 percent of Ag, which is realized on TiO by a photo-deposition method 2 3 times the photocatalytic hydrogen evolution activity of 0.2% Au was supported on 1.0 (FIGS. 12a, b). This shows that Ag loading shows a similar carrier effect as the Pt, au loading described above, i.e. by Ti under photo-induction 3 C 2 O x The noble metal particles with high dispersity can be obtained by mediating the transfer action of photo-generated electrons.
Further optimizing the photo-deposition method for preparing Ag-loaded TiO 2 /Ti 3 C 2 O x -1.0. It can be found that PM-zAg-TiO 2 /Ti 3 C 2 O x Hydrogen yield of 1.0The Ag loading increases and then decreases with increasing Ag loading. When Ag loading is 0.05%, the photocatalytic hydrogen evolution activity is 3.6mmol g -1 h -1 . When Ag loading increased to 0.1%, photocatalytic hydrogen evolution activity increased to 4.4mmol g -1 h -1 (FIG. 12 d). PM-0.5Ag-TiO while further increasing Ag loading 2 /Ti 3 C 2 O x -1.0 and PM-1.0Ag-TiO 2 /Ti 3 C 2 O x -1.0 hydrogen production was reduced to 5.0 and 4.3mmol g -1 h -1 . This is because at low Ag loading densities (0.05-0.1%), due to Ag and TiO 2 /Ti 3 C 2 O x A small contact surface of 1.0 results in an inability to efficiently absorb light and thus a decrease in photocatalytic activity. And the mutual contact and overlapping of the metal plating layers at higher Ag-carrying density reduces the efficiency of electron transfer of the interface.
Test example 6
Phase analysis of photocatalyst
TiO 2 /Ti 3 C 2 O x -y has an XRD pattern as shown in figure 1 (a). TiO synthesized in examples 1-4 2 /Ti 3 C 2 O x The (002) plane of MXene was observed in y, at 6.0. In addition, some sharp diffraction peaks were detected at 24.7, 37.2, 47.5, 53.3, 54.4 and 62.1 °, which is anatase TiO 2 The (101), (004), (200), (105), (211) and (204) crystal planes. At the same time with H 2 O 2 The addition amount was increased from 0.4mL to 1.3mL, ti 3 C 2 O x Gradually decreasing strength with anatase TiO 2 Is shown from Ti 3 C 2 O x To anatase TiO 2 Is along with H 2 O 2 The increase in volume also indicates that the highest amounts of TiO may be formed at moderate oxidation strengths 2 /Ti 3 C 2 O x And a heterojunction. The FT-IR spectrum of the different photocatalysts is shown in FIG. 1 (c). At 2927 and 2846cm -1 Two peaks at the position belong to Ti 3 C 2 O x C-H stretching of 1629cm -1 Is Ti at 3 C 2 O x C=o bond on the surface. At the same time, 3430cm -1 The signal at this point is due to the-OH bond, which is attributed to H 2 The O molecules are adsorbed on the surface of the material. In addition, tiO 2 /Ti 3 C 2 O x At 472cm -1 The vicinity has obvious characteristic peaks of Ti-O-Ti, and the intensity of the characteristic peaks depends on H 2 O 2 Is a volume of (c). A-TiO 2 And TiO 2 XRD patterns and FT-IR spectra of-1.0 are shown in FIG. 1 (b, d), demonstrating A-TiO 2 And TiO 2 -1.0 successful synthesis of material. In order to confirm the structure of the sample, raman spectroscopy was performed as shown in fig. 1 (e). The Raman spectrum shows two carbon-related peaks, with a disorder peak (D band) of 1362cm -1 Peak of graphite structure (G band) is 1602cm -1 。TiO 2 /Ti 3 C 2 O x Peak strength of D and G bands of composite material with H 2 O 2 The amount of (C) increases because the surface generates C when Ti atoms in MXene are bound to oxygen-containing groups on the carbon base surface. The high strength of the D-band indicates TiO 2 /Ti 3 C 2 O x There are a number of defects in it, these are H 2 The active adsorption sites of the O molecules contribute to the photocatalytic reaction. In addition, tiO 2 /Ti 3 C 2 O x -y has a Raman spectrum of 148, 395, 513, 638cm -1 Where a signal peak appears, corresponding to anatase TiO 2 E of (2) g 、B 1g 、B 2g And E is g Raman vibration, indicating the formation of anatase TiO 2 。
The catalyst was analyzed using uv-vis diffuse reflectance spectroscopy to reveal its light absorption characteristics and electronic band structure. As shown in FIG. 1 (f), ti 3 C 2 O x Exhibits strong absorption in the 200-800nm region. However, tiO 2 /Ti 3 C 2 O x The y composite forms a distinct band edge structure (at about 400 nm) after oxidation, which is TiO 2 Is arranged on the absorption edge of the (c).
N of the catalyst 2 The adsorption-desorption isotherms are shown in FIG. 1 (g). The material with the largest specific surface area is TiO 2 /Ti 3 C 2 O x -1.3, up to 76.9m 2 And/g. In addition, when synthesizing TiO 2 /Ti 3 C 2 O x H of composite material 2 O 2 The specific surface areas of the materials are 39.5, 28.9 and 64.1m when the volume dosage is 0.4, 0.7 and 1.0mL 2 And/g. The pore size distribution curve of the composite material is shown in FIG. 1 (h), which shows that the obtained TiO 2 /Ti 3 C 2 O x Y photocatalysts have a rich pore size distribution.
Test example 7
Microcosmic characterization of different photocatalysts
TiO 2 /Ti 3 C 2 O x SEM images of y are shown in figure 2. Initial Ti 3 C 2 O x After hydrothermal oxidation and post-annealing treatment, the lamellar microstructure is destroyed and becomes smaller fragments, and the fragments are packed together to form a sea urchin-like nano structure which consists of a plurality of aligned nano whiskers, namely TiO is formed 2 /Ti 3 C 2 O x -y。
The TiO prepared was further observed by TEM 2 /Ti 3 C 2 O x -1.0 microstructure. As shown in FIG. 3, it is clearly observed that the lattices with d-spacing of 0.33 and 1.14nm (FIGS. 3c, d), corresponding to Ti 3 C 2 O x (006) and (002) planes. Meanwhile, lattice spacing of 0.35 and 0.24nm may correspond to anatase TiO 2 The (101) and (004) planes. Ti (Ti) 3 C 2 O x And TiO 2 The lattice between the interfaces is continuously closely distributed, which aids in the transfer of the support during the photocatalytic reaction. In addition, in TiO 2 /Ti 3 C 2 O x A uniform distribution of Ti, O and C elements was observed in the EDX spectrum of-1.0 (FIG. 3 e), further demonstrating that TiO 2 Nanowhisker at Ti 3 C 2 O x And growing and uniformly distributing the materials in situ.
PM-0.2Pt-TiO 2 /Ti 3 C 2 O x SEM images of-1.0 are shown in fig. 4 (a). In contrast to TiO 2 /Ti 3 C 2 O x -1.0, after in situ deposition of Pt by photo-depositionThe appearance was not significantly changed. Lattices with d-spacing of 0.26 and 1.14nm (FIGS. 4 e-g) can be observed in the HRTEM image, corresponding to Ti 3 C 2 O x The (101) and (002) planes. At the same time, lattice spacing of 0.34nm can be corresponding to anatase TiO 2 The (101) crystal plane of (a). FIG. 4 (c) shows PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 selective electron diffraction (SAED), the depicted circles indicate the presence of polycrystalline structure in the catalyst, representing Pt (111) and (100) crystal planes, tiO 2 (101) Crystal face and Ti 3 C 2 O x (101) The results of the crystal planes are completely matched with those of the HRTEM images. In addition, in PM-0.2Pt-TiO 2 /Ti 3 C 2 O x A uniform distribution of Ti, C, O and Pt elements was observed in the EDX spectrum of-1.0 (FIG. 4 e), further demonstrating that Pt is present in TiO 2 /Ti 3 C 2 O x -1.0 ultra-dispersed uniform loading.
IM-0.2Pt-TiO 2 /Ti 3 C 2 O x SEM images of-1.0 are shown in fig. 5 (a). After deposition of Pt by immersion, the appearance did not change significantly. A lattice with d-spacing of 0.23nm can be observed in the HRTEM image (fig. 5 d), corresponding to Ti 3 C 2 O x The (103) crystal plane of (a). Meanwhile, a lattice spacing of 0.34nm may correspond to anatase TiO 2 The (101) crystal plane of (a). FIG. 5 (c) shows IM-0.2Pt-TiO 2 /Ti 3 C 2 O x- 1.0 Selective Electron diffraction (SAED), depicted circles indicate the presence of polycrystalline structure in the catalyst, representing Pt (111) and (100) crystal planes, tiO 2 (101) Crystal face and Ti 3 C 2 O x (103) The results of the crystal planes are completely matched with those of the HRTEM images. In addition, in IM-0.2Pt-TiO 2 /Ti 3 C 2 O x Ti, C, O and Pt elements were observed in the EDX pattern of-1.0 (FIG. 5 e), demonstrating the successful deposition of Pt on TiO by immersion 2 /Ti 3 C 2 O x -1.0.
PM-0.2Pt-TiO 2 An SEM image of-1.0 is shown in FIG. 6 (a). TiO (titanium dioxide) 2 -1.0 shows a rod-like structure, and TiO 2 /Ti 3 C 2 O x -y is different from sea urchin-like structures. Lattice spacings of d-spacing 0.34 and 0.60nm can be observed in the HRTEM image, which can correspond to anatase TiO 2 The (101) and (200) crystal planes. FIG. 6 (c) shows PM-0.2Pt-TiO 2 -1.0 selective electron diffraction (SAED), the depicted circles indicate the presence of a polycrystalline structure in the catalyst, representing the Pt (100) crystal plane, and TiO 2 (200) And (101) crystal planes, the results of which are exactly matched with those of the HRTEM images. In addition, in PM-0.2Pt-TiO 2 Ti, O and Pt elements were observed in the EDX pattern of-1.0 (FIG. 6 e), demonstrating successful deposition of Pt on TiO by photoinduction 2 -1.0.
PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 The Pt particle size distribution of-1.0 is shown in fig. 7. The order of average particle size of Pt on the three materials was found to be: PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0＜PM-0.2Pt-TiO 2 -1.0＜IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0。PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 having a Pt average particle diameter (1.38 nm) smaller than that of IM-0.2Pt-TiO 2 /Ti 3 C 2 O x Pt average particle diameter of 1.0 (2.59 nm), because the photo-deposition method is capable of depositing Pt having a smaller particle diameter than the immersion method (fig. 7 (a-d)). But if there is no Ti 3 C 2 O x The mediation of (a) resulted in electron aggregation, and the Pt particle size (fig. 7 (e, f), 1.75 nm) obtained by the photo-deposition was large and non-uniform. This demonstrates that to obtain highly dispersed Pt nanoparticles, photoinduction and Ti 3 C 2 O x Is indispensable for the mediation of the (C).
Test example 8
Surface composition and chemical state changes of different photocatalysts
Ti 3 C 2 T x And TiO 2 /Ti 3 C 2 O x XPS spectra of (a) C1s, (b) Ti 2p, (C) O1s and (d) F1 s of-1.0 as shown in FIG. 8, detected by XPS spectra, tiO 2 /Ti 3 C 2 O x The surface element composition results of-1.0 are shown in Table 1. Ti (Ti) 3 C 2 T x Five distinct peaks (FIG. 8 a) are present in the C1s spectrum at 282.1, 283.2, 284.7, 286.3 and 288.9eV, corresponding to the C-Ti, C-Ti-O, C-C, C-O and C-F bonds, respectively. In FIG. 8 (b), in Ti 3 C 2 T x Four groups of bimodals were detected in Ti 2p with an area ratio of 2:1 and a bimodal spacing of 5.7eV at 458.6, 457.6, 456.3 and 455.4eV, respectively, corresponding to TiO 2 、Ti x O y Ti-X (sub-stoichiometric TiC) x (X<1) Or titanium oxycarbonate) and Ti-C. As shown in FIG. 8 (c), ti 3 C 2 T x The O1s spectrum of (C) has four peaks at 529.8, 530.6, 531.8 and 533.7eV corresponding to adsorbed O species, ti-O-Ti, ti-OH and C-OH bonds. After the oxidation process, the strength of Ti-C is significantly reduced (FIG. 3 (a, b)), which is comparable to TiO 2 Is related to the intensity increase of (FIG. 8b, c), indicating Ti 3 C 2 T x Conversion to TiO 2 . It can be observed that with Ti 3 C 2 T x Partial oxidation to TiO 2 /Ti 3 C 2 O x The intensity of F1 s is significantly reduced (FIG. 8 d), while TiO 2 /Ti 3 C 2 O x The presence of adsorbed-O and Ti-O in 1.0 (FIG. 8 c) confirms the post-annealing TiO 2 /Ti 3 C 2 O x The surface end groups of the MXene in 1.0 are mainly-O adsorbed. By further analysis of Ti 3 C 2 T x And TiO 2 /Ti 3 C 2 O x The atomic percent of the element in 1.0 (table 1) was observed to drop sharply from 30.79% to 0.99% for F, while the O increased from 16.86% to 53.80%, further indicating the change in the surface adsorption groups on MXene.
TABLE 1 TiO 2 /Ti 3 C 2 O x -surface element composition of 1.0
C (atomic%) Ti (atomic%) O (atomic%) F (atomic%)
Ti 3 C 2 T x 34.49 19.06 16.43 30.02
TiO 2 /Ti 3 C 2 O x -1.0 18.80 26.41 53.80 0.99
FIG. 9 shows (a) PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and IM-0.2Pt-TiO 2 /Ti 3 C 2 O x C1s spectrum of-1.0 and PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 -1.0 of (b) Ti 2p, (c) O1 s and (d) Pt 4f spectra. From FIGS. 9 (a-c) and 8, it can be seen that Pt loading does not change TiO 2 And TiO 2 /Ti 3 C 2 O x Is a bond of (a). From FIG. 9d, it can be seen that three sets of double peaks, respectively elemental Pt, are detected in Pt 4f 0 And Pt (OH) in oxidation state 2 And Pt (Pt) 4+ The peak area ratio was 4:3, the peak spacing was 3.3eV, PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 The Pt ratios of different valence states in-1.0 are shown in table 2. As shown in FIG. 9 (d), PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 -1.0 Pt4f 7/2 (0) Binding energies were located at 71.39, 71.26, 71.30eV, respectively. PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 Pt4f 7/2 (0) Has larger binding energy, which indicates that the Pt nano particles are smaller. From Table 2, it can be seen that PM-0.2Pt-TiO 2 /Ti 3 C 2 O x Pt in 1.0 0 The highest content, indicating PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 is better in photocatalytic activity.
TABLE 2 PM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0、IM-0.2Pt-TiO 2 /Ti 3 C 2 O x -1.0 and PM-0.2Pt-TiO 2 -1.0 Pt duty cycle of different valence states
Test example 9
Photocatalytic mechanism
FIGS. 13 (a) and (d) are Ti 3 C 2 O x And A-TiO 2 (b) and (e) are Ti 3 C 2 O x And A-TiO 2 And (c) and (f) are Ti 3 C 2 O x And A-TiO 2 Is provided. To further understand TiO 2 /Ti 3 C 2 O x An electron transfer mechanism of the interface is carried outDensity Functional Theory (DFT) calculations are performed. With TiO 2 In comparison with Ti 3 C 2 O x The metallic character of the continuous electron states with crossing fermi levels (fig. 13a, b), consisting mainly of C2 p and Ti 3d orbitals, suggests that it has excellent conductivity. Furthermore, DFT calculations indicate Ti 3 C 2 O x Has a work function of 6.15eV (FIG. 13 b), compared with A-TiO 2 Is 0.3eV higher (5.85 eV, fig. 13 e).
For Ti 3 C 2 O x And A-TiO 2 Ultraviolet electron spectroscopy (UPS) testing was performed to further elucidate TiO 2 /Ti 3 C 2 O x Interface electron transfer kinetics of (c). As shown in FIG. 13 (c), (f), ti 3 C 2 O x And A-TiO 2 The secondary electron cut-off values of (c) are 17.42 and 17.75eV, respectively. By subtracting the He I excitation energy (21.22 eV), their work functions can be calculated to be 3.80 and 3.47eV, respectively, consistent with the trend of DFT calculations. The work function calculated by DFT is about 2.4eV higher than the work function measured by UPS. This is because DFT computation has some limitations and it is difficult to select a function base for accurately describing the vacuum level and work function absolute value computation. And the measured and calculated materials may be slightly different. Even so, both DFT calculations and UPS measurements clearly indicate Ti end capped with-O 3 C 2 O x With a ratio of A-TiO 2 Higher work function, in other words, its fermi level position is lower than that of A-TiO 2 . Based on the difference between the DFT calculation and the UPS measurement, the average of these two values is taken as the work function. Namely Ti 3 C 2 O x And A-TiO 2 Work functions of 4.98 and 4.66eV, respectively.
FIG. 14 shows (a) A-TiO 2 And (b) TiO 2 /Ti 3 C 2 O x -Mott-Schottky graph of 1.0, (c) A-TiO 2 And TiO 2 /Ti 3 C 2 O x -band gap of 1.0, the inset in (c) being A-TiO 2 And TiO 2 /Ti 3 C 2 O x -a DRUV-vis spectrum of 1.0. The position of the Valence Band (VB) and Conduction Band (CB) of the photocatalyst plays a key role in the transfer of photo-generated carriers and the photocatalytic performanceActing as a medicine. Thus, the band structure of the photocatalyst was analyzed by Mott-Schottky chart and DRUV-vis spectroscopy. A-TiO 2 And TiO 2 /Ti 3 C 2 O x The slope of the Mott-Schottky graph of-1.0 is positive (FIGS. 14a, b) because of TiO 2 Is an n-type semiconductor, and the measured flat band potential can be approximated as a conduction band edge (E CB ) And (3) a potential.
As shown in FIGS. 14 (a), (b), A-TiO 2 And TiO 2 /Ti 3 C 2 O x E of 1.0 CB The potentials were-0.98 and-0.52V for Ag/AgCl at ph=6.5, respectively, i.e., 0.40 and 0.06V with standard hydrogen potential as reference (NHE) at ph=0, respectively, converted by equations 1, 2.
E Ag / AgCl ＝E RHE -0.0591*pH-0.197………………………………………………(1)
E NHE ＝E RHE -0.0591*pH……………………………………………………………2
The optical absorption is described by DRUV-vis (FIG. 14 c). With pure A-TiO 2 In comparison with TiO 2 /Ti 3 C 2 O x 1.0 shows a pronounced red shift and a stronger absorption around 400 nm. The bandgap of the prepared photocatalyst is further illustrated by the Tauc diagram. As shown in FIG. 14 (c), A-TiO 2 And TiO 2 /Ti 3 C 2 O x Band gap estimates of 1.0 are 2.90 and 2.67eV, respectively. Bond E CB The potential can be calculated as A-TiO 2 And TiO 2 /Ti 3 C 2 O x Valence band of 1.0 (E VB ) The potentials were 2.50 and 2.73V (standard hydrogen potential as reference).
Based on the experimental and calculation results, the prepared sea urchin-shaped TiO is provided 2 /Ti 3 C 2 O x A possible photocatalytic mechanism (fig. 15). Ti (Ti) 3 C 2 O x Phi (4.98 eV) higher than A-TiO 2 Phi (4.66 eV), indicating Ti 3 C 2 O x Fermi level of (2) is lower than TiO 2 A kind of electronic device. Once they are in contact, in order to produce a magnetic field in Ti 3 C 2 O x And TiO 2 An equilibrium state is established between them, and negative charges are diffused to Ti 3 C 2 O x While positive charges remain in the TiO 2 On, form a secondary TiO 2 To Ti (Ti) 3 C 2 O x Is shown (fig. 15 a). In the photocatalytic reaction, photo-generated electron/hole pairs are respectively formed in TiO 2 Is excited on CB and VB of (c) and migrates under the influence of an internal electric field. Subsequently, positive charges are combined with TiO 2 /Ti 3 C 2 O x Negative charge neutralization at the interface, while photo-generated electrons accumulate in TiO 2 CB of (c). Finally, the photogenerated electrons are transferred to Ti through the Schottky junction 3 C 2 O x The formed Schottky barrier will prevent the photo-generated electrons from returning to TiO 2 Thereby achieving spatial separation of the photogenerated electrons and holes as shown in fig. 15 (b). These results indicate that Ti has a high work function and excellent conductivity 3 C 2 O x Play a key role in the separation and transfer of the photogenerated carrier and its participation in the photochemical reaction (fig. 15 b). Thus acting as mediating photo-generated electrons Ti 3 C 2 O x Conductive TiO 2 The photo-generated electrons at the surface are such that they do not react with TiO 2 Surface aggregation, so that noble metal can not be added in TiO 2 The surface aggregation load, namely, the high-dispersity noble metal particles can be obtained by deposition under the light induction effect.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted equally without departing from the spirit and scope of the technical solution of the present invention.

Claims (9)

1. A method for preparing a photocatalyst, comprising the steps of:
(1) Ti is mixed with 3 C 2 T x Lye and H 2 O 2 The solution is Ti in mass volume ratio 3 C 2 T x : alkali liquor: h 2 O 2 Solution = 200 mg:60 mL: mixing evenly 0.4-1.3 and mL to obtain mixed solution; carrying out hydrothermal reaction on the mixed solution to obtain meta-titanate/Ti 3 C 2 T x The precipitate was collected by filtration and the prepared meta-titanate/Ti was washed with water 3 C 2 T x Washing the composite material to neutrality and drying;
(2) Neutralizing the meta-titanate/Ti obtained in step (1) with an acid 3 C 2 T x Composite material to obtain H 2 Ti 3 O 7 /Ti 3 C 2 T x The method comprises the steps of carrying out a first treatment on the surface of the Collecting solid by suction filtration, washing with water until the filtrate is neutral, freeze drying, and collecting dried H 2 Ti 3 O 7 /Ti 3 C 2 T x Heating the composite material under the protection gas to obtain TiO 2 /Ti 3 C 2 O x ，Heating at 500-700 deg.C for 4 hr;
(3) TiO prepared in step (2) 2 /Ti 3 C 2 O x Adding acid or salt solution containing noble metal, and irradiating with 280-320-W xenon lamp to obtain noble metal loaded TiO 2 /Ti 3 C 2 O x And the noble metal is one of gold, silver and platinum.
2. The method for producing a photocatalyst according to claim 1, wherein in the step (1), ti 3 C 2 T x With lye and H 2 O 2 The mass volume ratio of the solution is Ti 3 C 2 T x : alkali liquor: h 2 O 2 Solution = 200 mg:60 mL:0.7-1.0 mL; the lye comprises NaOH, KOH, mg (OH) 2 At least one of the above-mentioned lyes OH - The concentration is 10 mol/L, H 2 O 2 H in solution 2 O 2 The concentration of (C) was 9.79 mol/L.
3. The method for preparing a photocatalyst according to claim 1, wherein in the step (1), the hydrothermal reaction is carried out at a temperature of 160 to 200 ℃ for 20 to 28 hours.
4. The method for preparing a photocatalyst according to claim 1, wherein in the step (2), the shielding gas is nitrogen, helium or argon.
5. The method of preparing a photocatalyst according to claim 1, wherein in the step (3), the acid solution containing a noble metal is chloroplatinic acid, chloroauric acid, and the salt in the salt solution containing a noble metal is silver nitrate.
6. The method for producing a photocatalyst according to claim 1 or 5, wherein the noble metal is one of platinum and gold; the acid solution containing noble metal is one of chloroplatinic acid and chloroauric acid.
7. The method for producing a photocatalyst according to claim 1, wherein the noble metal-supported TiO 2 /Ti 3 C 2 O x And the loading of the noble metal in the photocatalyst is 0.05-2.0wt% of the base photocatalyst.
8. A photocatalyst produced by the production process according to any one of claims 1 to 7.
9. Use of the photocatalyst of claim 8 in photocatalytic hydrogen production.
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