CN114984965A - P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 Preparation method and application thereof - Google Patents

P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 Preparation method and application thereof Download PDF

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CN114984965A
CN114984965A CN202210595562.XA CN202210595562A CN114984965A CN 114984965 A CN114984965 A CN 114984965A CN 202210595562 A CN202210595562 A CN 202210595562A CN 114984965 A CN114984965 A CN 114984965A
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mtio
composite photocatalyst
water
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CN114984965B (en
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尹升燕
杨俊锋
董妍惠
崔皓
佘萍
孙航
秦伟平
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Jilin University
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/78—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali- or alkaline earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B01J35/39—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/10—Heat treatment in the presence of water, e.g. steam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
    • C01B3/042—Decomposition of water
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Abstract

P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 The preparation method and the application thereof in hydrogen production by photocatalytic water splitting belong to the technical field of energy storage and conversion, and M is Ca, Sr or Ba. Under the irradiation of simulated sunlight, photo-generated electrons and holes are generated in the p-n heterojunction composite photocatalyst. Meanwhile, under the action of an internal electric field, photo-generated electrons are emitted from Cu 2 Conduction band flow direction of O to MTiO 3 Conduction band of, reduction of H + To obtain H 2 (ii) a Photogenerated hole from MTiO 3 Valence band flux of Cu 2 The valence band of O is finally consumed by the sacrificial reagent methanol, the recombination of photogenerated electron-hole pairs is inhibited, and the improvementCu 2 O/MTiO 3 The hydrogen activity of the decomposed water of the composite photocatalyst is generated. The composite photocatalyst Cu has strong light absorption capacity in an ultraviolet visible light region and can enhance photoelectric conversion performance, so that the composite photocatalyst Cu 2 O/MTiO 3 Has certain application prospect in the field of solar cells.

Description

P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 Preparation method and application thereof
Technical Field
The invention belongs to the technical field of energy storage and conversion, and particularly relates to a p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 The preparation method and the application thereof in hydrogen production by photocatalytic water splitting (M is Ca, Sr or Ba).
Background
Nowadays, with the rapid growth of global population and the continuous improvement of quality of life, fossil fuels (such as petroleum, coal, natural gas and the like) are largely consumed, which brings energy crisis and environmental pollution problems in the global scope, and simultaneously, the demand of the world for carbon-free green energy sources such as solar energy, hydroenergy, hydrogen energy, wind energy, tidal energy and the like is greatly improved. Among them, hydrogen energy is an important sustainable carbon-free clean energy and will play an important role in the world energy pattern. In recent years, a photocatalytic water splitting hydrogen production technology becomes an attractive technology for constructing a clean renewable energy system, and the technology stores solar energy in a chemical bond form and is considered to be an ideal method for converting the solar energy into the hydrogen energy. Moreover, more and more researches show that the key of photocatalytic water decomposition for hydrogen production is to find a high-efficiency photocatalyst material. Therefore, researchers have expended a great deal of effort to synthesize different types of photocatalysts, which can be simply divided into single semiconductor materials and semiconductor heterojunction composites, byThe separation rate of the high photo-generated carrier pairs is increased, the recombination efficiency of the high photo-generated carrier pairs is reduced, and the water-evolution hydrogen activity of the photocatalytic decomposition is effectively improved. Recently, p-n heterojunctions have been favored by researchers because they can form built-in electric fields and effectively promote the separation and migration of photogenerated electron-hole pairs. For example, Qianqian Chi (Nanoscale,2021,13,4496- 2 And BiOBr constructs a p-n heterojunction with a strong built-in electric field, and the built-in electric field greatly accelerates the separation and migration of photo-generated electron-hole pairs. Under the irradiation of visible light (lambda)>420nm) when TiO is used 2 And BiOBr at a molar ratio of 3:1, the best photocatalytic total water splitting performance is shown: the hydrogen evolution rate and the oxygen evolution rate are 472.7 mu mol g and respectively -1 h -1 And 95.7. mu. mol g -1 h -1 . Maha Alhadladd (J.Mater.Res.Technol.2020,9,15335-15345) et al prepared mesoporous Cu by soft template and hard template sol-gel method respectively 2 O and g-C 3 N 4 Then preparing Cu by using an ultrasonic-assisted mixing method 2 O/g-C 3 N 4 A p-n heterojunction composite material. Under simulated solar radiation, Cu 2 O/g-C 3 N 4 The highest hydrogen evolution rate of the composite samples was Cu, respectively 2 O and g-C 3 N 4 17 and 38 times. Therefore, constructing a low-cost and efficient p-n heterojunction composite material for photocatalytic decomposition of water to produce hydrogen remains a very significant task.
Perovskite oxide MTiO 3 (M ═ Mg, Ca, Sr, Ba, Pb, and the like) has been widely studied in the fields of photocatalysts, superconductors, thermoelectrics, ferroelectrics, piezoelectrics, and dielectric devices, etc. because of its unique physicochemical properties. Moreover, titanate is considered as a promising photocatalyst material due to its advantages of excellent light corrosion resistance, high thermal stability, non-toxicity and low cost. In addition, cuprous oxide (Cu) 2 O) can absorb visible light (E) g About 2.2eV), is widely used for photocatalytic decomposition of water and degradation of organic pollutants, and has the advantages of low toxicity, low cost and the like. MTiO 3 And Cu 2 O is typically an n-and p-type semiconductor, respectively, once p-Cu is added 2 O nanoparticle loading to n-MTiO 3 On the surface of Cu 2 O/MTiO 3 The p-n heterojunction is constructed in the composite material, and an electric field built in the p-n heterojunction is favorable for separation and transfer of photo-generated electron-hole pairs, so that the improvement of the photocatalytic hydrogen production activity is promoted. Thus constructing Cu 2 O/MTiO 3 It is significant to study the photocatalytic hydrogen production performance of p-n heterojunction composite materials.
Disclosure of Invention
The invention aims to provide a novel p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 。
The invention utilizes a hydrothermal method and NaBH 4 P-n heterojunction composite photocatalyst Cu constructed by reduction method 2 O/MTiO 3 . When Cu 2 O and MTiO 3 The p-n heterojunction is formed after contact, and due to the carrier concentration gradient, electrons from the n-region (MTiO) just before diffusion movement occurs 3 ) Flow to p region (Cu) 2 O), holes flow from the p-region to the n-region, and when equilibrium is reached, a built-in electric field is created in the p-n heterojunction. Therefore, under simulated solar irradiation, under Cu 2 O/MTiO 3 photogenerated electrons and holes are generated in the p-n heterojunction recombination sample. Meanwhile, under the action of an internal electric field, photo-generated electrons are emitted from Cu 2 Conduction band flow direction of O to MTiO 3 Conduction band of, reduction of H + To obtain H 2 (ii) a Photogenerated hole from MTiO 3 Valence band flux of Cu 2 The valence band of O is finally consumed by the sacrificial reagent methanol, the recombination of photogenerated electron-hole pairs is inhibited, and the Cu content is improved 2 O/MTiO 3 The hydrogen activity of the decomposed water of the composite photocatalyst is generated. Further, Cu 2 O/MTiO 3 The composite material can also be made into an electrode material, has good photoelectric response and strong light absorption capacity under the irradiation of ultraviolet and visible light, and can enhance the photoelectric conversion performance to ensure that the composite photocatalyst Cu is prepared 2 O/MTiO 3 Has certain application prospect in the field of solar cells.
The p-n heterojunction composite photocatalyst Cu prepared by the invention 2 O/MTiO 3 The photocatalytic efficiency can be improved by the following three aspects: 1. hollow MTiO 3 Has large specific surface area, is not only beneficial to Cu 2 Negative of O nanoparticlesThe photocatalyst can be loaded and can provide more photocatalytic active sites; 2. cu 2 O and MTiO 3 The built-in electric field effect between the two can accelerate the separation and migration of photo-generated electron-hole pairs. Therefore, the p-n heterojunction composite photocatalyst Cu prepared by the invention 2 O/MTiO 3 The separation and migration of photogenerated charges can be effectively promoted from multiple aspects, and the recombination efficiency of the photogenerated charges is reduced, so that the performance of photocatalytic hydrogen production is improved. The composite photocatalyst has the advantages of simple preparation method, obviously improved photoelectric conversion efficiency and high-efficiency hydrogen production effect by photocatalytic water decomposition.
The invention relates to a p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 The preparation method comprises the following steps:
1)Cu 2 preparation of O
Dissolving 30-70 mg of water-soluble copper salt and 10-30 mg of polyvinylpyrrolidone (PVP) in a mixed solvent containing 9-21 mL of water-soluble alcohol solvent and 21-49 mL of water, magnetically stirring for 3-5 min, and then performing ultrasonic treatment for 10-15 min; then 0.1-0.2 g of NaBH is added under magnetic stirring 4 Adding the mixture into the solution, performing magnetic stirring reaction for 4-6 hours, and performing ultrasonic treatment for 20-40 min; then centrifugally washing the obtained precipitate with deionized water and absolute ethyl alcohol for multiple times, and drying for 8-12 h at 50-60 ℃ to obtain Cu 2 O；
2)MTiO 3 Preparation of
Firstly, 1.18 to 3.54g M (NO) 3 ) 2 ·4H 2 Dissolving O in 20-60 mL of deionized water, magnetically stirring for 10-20 min, and adding 1.7-5.1 mL of Ti (C) 4 H 9 O) 4 And 0.4-1.2 g of NaOH, magnetically stirring for 1-2 h, transferring the obtained white suspension liquid into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, and performing hydrothermal treatment at 180-200 ℃ for 24-36 h; after the reaction is finished, naturally cooling the reaction kettle to room temperature, washing the obtained white precipitate to be neutral by using an acetic acid aqueous solution (the volume fraction is 20-30%), then centrifugally washing the obtained precipitate by using deionized water and absolute ethyl alcohol for multiple times, and drying for 8-12 h at the temperature of 60-80 ℃ to obtain MTiO 3 M is Ca, Sr or Ba;
when reactingGenerating MTiO 3 Then, if M (NO) 3 ) 2 ·4H 2 O or Ti (C) 4 H 9 O) 4 When the amount of the substance(s) is different, the excess sample does not affect the product, whichever is excessive after the reaction is completed, and the excess raw material is removed in the subsequent washing process. The samples obtained from different raw material amounts have the same properties, basically consistent yields, but higher yields, and no influence on the latter properties.
3) Composite photocatalyst Cu 2 O/CaTiO 3 Preparation of
2-50 mg of water-soluble copper salt and 20-70 mg of MTiO 3 And 10-30 mg of polyvinylpyrrolidone (PVP) are added into a mixed solvent containing 9-21 mL of water-soluble alcohol solvent and 21-49 mL of water, magnetic stirring is carried out for 3-5 min, and then ultrasonic treatment is carried out for 10-15 min; then 0.1-0.2 g of NaBH is added under magnetic stirring 4 Adding the mixture into the solution, reacting for 4-6 hours by magnetic stirring, and then carrying out ultrasonic treatment for 20-40 min; centrifugally washing the obtained precipitate with deionized water and absolute ethyl alcohol for multiple times, and drying at 50-60 ℃ for 8-12 hours to obtain the p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 M is Ca, Sr or Ba.
4) Hydrogen production step by photocatalyst
The photocatalytic hydrogen production experiment uses an online photocatalytic hydrogen production system (CEL-PAEM-D8, Zhongzhijin company), and the temperature is controlled to be about 6 ℃; simulating sunlight (300-1100nm) by using a 300W Xe lamp (covering cut-off filter: JB 300) as a light source; 30mg of composite photocatalyst Cu 2 O/MTiO 3 Dispersed in a mixed solution containing 6mL of methanol (sacrificial agent) and 24mL of deionized water; before turning on the xenon lamp, vacuumizing for 30 minutes by using a vacuum pump to ensure that the reaction environment is in a vacuum state; hydrogen was extracted every hour and analyzed by an on-line gas chromatograph (GC 7920-DTA).
The water-soluble copper salt in step 1) may be Cu (CH) 3 COO) 2 、CuSO 4 、CuCl 2 、Cu(NO 3 ) 2 One of (1); the PVP can be one of K30 and K60; the water-soluble alcohol is ethylene glycol, isopropanol, anhydrous ethanol, n-propanol, n-butanol, and i-butanolOne of alcohol, cyclohexanol, 1, 3-propylene glycol and glycerol; the rotating speed of magnetic stirring is 200-400 rpm, and the rotating speed of centrifugation is 5000-10000 rpm;
ca (NO) in step 2) 3 ) 2 ·4H 2 O may be replaced by Sr (NO) 3 ) 2 And Ba (NO) 3 ) 2 Instead of preparing SrTiO 3 And BaTiO 3 (ii) a The rotating speed of magnetic stirring is 200-400 rpm, and the rotating speed of centrifugation is 5000-10000 rpm;
the water-soluble copper salt in step 3) may be Cu (CH) 3 COO) 2 、CuSO 4 、CuCl 2 、Cu(NO 3 ) 2 One of (1); the PVP can be one of K30 and K60; the water-soluble alcohol is one of ethylene glycol, isopropanol, anhydrous ethanol, n-propanol, n-butanol, isobutanol, cyclohexanol, 1, 3-propanediol and glycerol; the rotating speed of the magnetic stirring is 200-400 rpm; the centrifugal rotating speed is 5000-10000 rpm.
The invention relates to a p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 Is prepared by the method.
The invention relates to a p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 Can be applied to photocatalytic hydrogen production.
Drawings
FIG. 1: FIG. (a) shows Cu in example 1 2 A photograph of a real object of the O photocatalyst, wherein FIG. (b) is a CaTiO photocatalyst in example 1 3 Photo of photocatalyst in real form, and FIG. C shows Cu in example 1 2 O/CaTiO 3 Photo of photocatalyst.
FIG. 2 is a schematic diagram: FIG. (a) shows Cu in example 1 2 O、CaTiO 3 And Cu 2 O/CaTiO 3 X-ray diffraction pattern of the photocatalyst, and FIG. (b) shows Cu in examples 1,2,3,4 and 5 2 O/CaTiO 3 X-ray diffraction spectrum of the photocatalyst.
FIG. 3: FIGS. (a, b) are Cu in example 1, respectively 2 O/CaTiO 3 Transmission electron micrographs and high power transmission electron micrographs of the photocatalyst.
FIG. 4: for Cu in example 1 2 O、CaTiO 3 And Cu 2 O/CaTiO 3 And (3) a hydrogen production rate point diagram of the photocatalyst.
FIG. 5 is a schematic view of: is Cu in example 1 2 O、CaTiO 3 And Cu 2 O/CaTiO 3 Ultraviolet-visible diffuse reflectance spectrum of photocatalyst.
FIG. 6: is CaTiO in example 1 3 And Cu 2 O/CaTiO 3 Photoelectric response curve of the photocatalyst under the irradiation of ultraviolet and visible light.
FIG. 7: is CaTiO in example 1 3 And Cu 2 O/CaTiO 3 Photoluminescence spectrum (excitation wavelength 340nm) of the photocatalyst.
Detailed Description
The technical solution of the present invention is described in more detail with reference to the following specific examples, which are not intended to limit the present invention.
Example 1
1)Cu 2 Preparation of O-photocatalyst
50mg of Cu (CH) 3 COO) 2 ·H 2 O and 20mg PVP (K30) were dissolved in 50mL of an aqueous solution containing 15mL of ethylene glycol, magnetically stirred for 5min (rotation speed of magnetic stirring 300rpm), and then sonicated for 10 min. Then 0.15g NaBH in a fume hood with magnetic stirring 4 Adding into the above solution, reacting for 4h with magnetic stirring (the rotation speed of magnetic stirring is 300rpm), and performing ultrasonic treatment for 30 min. Then centrifugally washing the obtained precipitate for multiple times (the centrifugal rotating speed is 8000rpm) by using deionized water and absolute ethyl alcohol, and drying for 12h at the temperature of 60 ℃ to obtain Cu 2 O, product mass about 10 mg.
2)CaTiO 3 Preparation of the photocatalyst
First, 1.18g Ca (NO) is added 3 ) 2 ·4H 2 O was dissolved in 20mL of deionized water, magnetically stirred for 10min (the rotation speed of the magnetic stirrer was 300rpm), and then 1.7mL of Ti (C) was added to the above solution 4 H 9 O) 4 And 0.4g NaOH. After further magnetic stirring for 1 hour (the rotational speed of magnetic stirring was 300rpm), the white suspension was transferred to a 30mL stainless steel autoclave lined with polytetrafluoroethylene, and subjected to hydrothermal treatment at 180 ℃ for 24 hours. After the reaction, the reaction kettle is naturally cooled to room temperature. Finally, theWashing the white precipitate with acetic acid water solution (volume fraction of 30%) to neutrality, centrifuging the obtained precipitate with deionized water and anhydrous ethanol for several times (rotation speed of 8000rpm), and oven drying at 60 deg.C for 12 hr to obtain CaTiO 3 The mass of the product was about 0.4 g.
3)Cu 2 O/CaTiO 3 Preparation of the photocatalyst
10mg of Cu (CH) 3 COO) 2 ·H 2 O、50mg CaTiO 3 And 20mg PVP (K30) was dissolved in 50mL of an aqueous solution containing 15mL of ethylene glycol, magnetically stirred for 5min and then sonicated for 10 min. Then 0.15g NaBH in a fume hood with magnetic stirring 4 Adding into the above solution, reacting for 4h under magnetic stirring, and performing ultrasonic treatment for 30 min. Then centrifugally washing the obtained precipitate for multiple times (the centrifugal rotating speed is 8000rpm) by using deionized water and absolute ethyl alcohol, and drying for 12h at the temperature of 60 ℃ to obtain the composite photocatalyst Cu 2 O/CaTiO 3 The product mass was about 30 mg.
4) Hydrogen production step by photocatalyst
The photocatalytic hydrogen production experiment uses an online photocatalytic hydrogen production system (CEL-PAEM-D8, Zhongzhijin company), and the temperature is controlled to be about 6 ℃; simulating sunlight (300-; 30mg of composite photocatalyst Cu 2 O/MTiO 3 Dispersed in a mixed solution containing 6mL of methanol (sacrificial agent) and 24mL of deionized water; before turning on the xenon lamp, vacuumizing for 30 minutes by using a vacuum pump to ensure that the reaction environment is in a vacuum state; hydrogen was extracted every hour and analyzed by on-line gas chromatography (GC 7920-DTA).
The composite photocatalyst Cu prepared by the invention 2 O/CaTiO 3 Light absorption range of (1) compared to pure CaTiO 3 Extends from about 360nm to about 520nm, enhances visible light absorption, and with Cu 2 The color of the composite material turns green due to the loading of the O nano particles. In a hollow CaTiO 3 A layer of Cu is loaded on the surface of the (n-type semiconductor) 2 The O nano particles (p-type semiconductor) form a p-n heterojunction composite material, can effectively promote the separation and migration of photogenerated electron-hole pairs and reduce the recombination efficiency of the photogenerated electron-hole pairs, therebyThe performance of photocatalytic hydrogen production is improved.
As shown in FIG. 1, the sample colors were dark green (panel a), white (panel b) and light green (panel c), respectively, with Cu 2 Load of O, Cu 2 O/CaTiO 3 The color of the catalyst turns green, and the photoresponse range of the composite material is also extended to the visible light region.
As shown in FIG. 2, the name of the composite sample is defined based on the amount of the starting reactant (e.g., 50mg CaTiO) 3 And 2mg of Cu (CH) 3 COO) 2 ·H 2 The sample obtained was defined as 50Ca2 Cu; 50mg of CaTiO 3 And 10mg of Cu (CH) 3 COO) 2 ·H 2 The sample obtained was defined as 50Ca10 Cu). When the amount of the added copper acetate is less than or equal to 20mg, no Cu exists in an XRD spectrogram 2 Diffraction peak of O, indicating Cu 2 The content of O is low; when the amount of copper acetate added was 50mg, Cu began to appear in the XRD spectrum 2 Characteristic diffraction peak of O at 36.6 deg. indicating by hydrothermal method and NaBH 4 Reduction method we successfully prepared Cu 2 O/CaTiO 3 A composite photocatalyst (figure b).
As shown in FIG. 3, Cu in FIG. a 2 The O nano particles are uniformly dispersed in the hollow CaTiO 3 Of (2) is provided. Two different lattice fringes (0.243nm and 0.269nm) can be clearly seen in FIG. b, corresponding to Cu, respectively 2 O and CaTiO 3 Further indicating that we succeeded in preparing Cu with (111) and (121) planes 2 O/CaTiO 3 A composite photocatalyst is provided.
As shown in figure 4, the p-n heterojunction composite photocatalyst Cu 2 O/CaTiO 3 The hydrogen production rate is 8.268mmol g -1 h -1 Is pure CaTiO 3 (0.024mmol g -1 h -1 ) About 344.5 times that of the sample, and Cu 2 The hydrogen production rate of O was almost 0, indicating that Cu is included 2 O and CaTiO 3 The p-n heterojunction composite photocatalyst can greatly improve the photocatalytic hydrogen production rate.
As shown in fig. 5, since Cu 2 The load of O nano-particles, the light absorption range of the composite material is compared with that of pure CaTiO 3 360nm to 520nm, an expanded light absorption range, ofIs beneficial to improving the photocatalytic hydrogen production rate.
As shown in FIG. 6, Cu was irradiated with light 2 O/CaTiO 3 The photocurrent intensity is obviously stronger than that of CaTiO 3 Is shown in Cu 2 O/CaTiO 3 The separation and transfer rate of the surface photogenerated electron-hole pair is greatly improved, which is beneficial to improving the photocatalytic hydrogen production rate.
As shown in FIG. 7, Cu 2 O/CaTiO 3 The photoluminescence intensity of the phosphor is obviously weaker than that of CaTiO 3 Is shown in Cu 2 O/CaTiO 3 The recombination of surface photoproduction electron-hole pairs is effectively delayed, which is beneficial to improving the photocatalytic hydrogen production rate.
Example 2
The procedure is as in example 1,2,3 and 4 steps, except that Cu is prepared in example 2 2 O/CaTiO 3 When the photocatalyst is compounded, Cu (CH) in the step 3 is added 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 2mg to obtain Cu 2 O/CaTiO 3 The product quality of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 6.939mmol g -1 h -1 。
Example 3
The procedure is as in example 1,2,3 and 4 steps, except that Cu is prepared in example 3 2 O/CaTiO 3 When the photocatalyst is compounded, Cu (CH) in the step 3 is added 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 5mg to obtain Cu 2 O/CaTiO 3 The product quality of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 7.724mmol g -1 h -1 。
Example 4
The procedure is as in example 1,2,3 and 4 steps, except that Cu is prepared in example 4 2 O/CaTiO 3 When the photocatalyst is compounded, Cu (CH) in the step 3 is added 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 20mg to obtain Cu 2 O/CaTiO 3 The product quality of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 7.257mmol g -1 h -1 。
Example 5
The same procedure as in 2,3 and 4 steps of example 1 was conducted, except that Cu was prepared in example 5 2 O/CaTiO 3 When the photocatalyst is compounded, Cu (CH) in the step 3 is added 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 50mg to obtain Cu 2 O/CaTiO 3 The product quality of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 5.229mmol g -1 h -1 。
Example 6
The same procedure as in 2,3 and 4 steps of example 1 was conducted, except that Cu was prepared in example 6 2 O/SrTiO 3 When the photocatalyst is compounded, 1.18g of Ca (NO) in the step 2 3 ) 2 ·4H 2 O is changed to 1.06g Sr (NO) 3 ) 2 In step 3, 50mg of CaTiO 3 Exchanged to 50mg SrTiO 3 And Cu (CH) 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 20mg to finally obtain Cu 2 O/SrTiO 3 The product quality of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 1.730mmol g -1 h -1 。
Example 7
The procedure is as in example 1,2,3 and 4 steps, except that Cu is prepared in example 7 2 O/BaTiO 3 When the photocatalyst is compounded, 1.18g of Ca (NO) in the step 2 3 ) 2 ·4H 2 O is changed to 1.31g Ba (NO) 3 ) 2 In step 3, 50mg of CaTiO 3 Exchanged to 50mg BaTiO 3 And Cu (CH) 3 COO) 2 ·H 2 Changing the mass of O from 10mg to 20mg to finally obtain Cu 2 O/BaTiO 3 The product mass of the composite photocatalyst is about 30 mg. The hydrogen production rate of the catalyst is 0.249mmol g -1 h -1 。

Claims (5)

1. P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 The preparation method comprises the following steps:
1)MTiO 3 preparation of
Firstly, 1.18 to 3.54g M (NO) 3 ) 2 ·4H 2 Dissolving O in 20-60 mL of deionized waterMagnetically stirring in water for 10-20 min, and adding 1.7-5.1 mL of Ti (C) 4 H 9 O) 4 And 0.4-1.2 g of NaOH, magnetically stirring for 1-2 h, transferring the obtained white suspension liquid into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, and performing hydrothermal treatment at 180-200 ℃ for 24-36 h; after the reaction is finished, naturally cooling the reaction kettle to room temperature, washing the obtained white precipitate to be neutral by using dilute acetic acid aqueous solution, then centrifugally washing the obtained precipitate for multiple times by using deionized water and absolute ethyl alcohol, and drying for 8-12 h at the temperature of 60-80 ℃ to obtain MTiO 3 M is Ca, Sr or Ba;
2) composite photocatalyst Cu 2 O/CaTiO 3 Preparation of
2-50 mg of water-soluble copper salt and 20-70 mg of MTiO 3 And 10-30 mg of polyvinylpyrrolidone are added into a mixed solvent containing 9-21 mL of water-soluble alcohol solvent and 21-49 mL of water, and the mixture is subjected to magnetic stirring for 3-5 min and then ultrasonic treatment for 10-15 min; then, 0.1-0.2 g of NaBH is added under magnetic stirring 4 Adding the mixture into the solution, performing magnetic stirring reaction for 4-6 hours, and performing ultrasonic treatment for 20-40 min; centrifugally washing the obtained precipitate with deionized water and absolute ethyl alcohol for multiple times, and drying at 50-60 ℃ for 8-12 hours to obtain the p-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 M is Ca, Sr or Ba.
2. The p-n heterojunction composite photocatalyst Cu as claimed in claim 1 2 O/MTiO 3 The preparation method is characterized in that: in the step 1), the rotating speed of magnetic stirring is 200-400 rpm, and the rotating speed of centrifugation is 5000-10000 rpm.
3. The p-n heterojunction composite photocatalyst Cu as claimed in claim 1 2 O/MTiO 3 The preparation method is characterized by comprising the following steps: the copper salt soluble in water in the step 2) is Cu (CH) 3 COO) 2 、CuSO 4 、CuCl 2 、Cu(NO 3 ) 2 One of (1); the polyvinylpyrrolidone is one of K30 and K60; the water-soluble alcohol is ethylene glycol, isopropanol, anhydrous ethanol, n-propanol, n-butanol, isobutanol, cyclohexanol, 1,3-One of propylene glycol and glycerol; the rotating speed of the magnetic stirring is 200-400 rpm; the centrifugal rotating speed is 5000-10000 rpm.
4. P-n heterojunction composite photocatalyst Cu 2 O/MTiO 3 The method is characterized in that: is prepared by the method of any one of claims 1 to 3.
5. The p-n heterojunction composite photocatalyst Cu as claimed in claim 4 2 O/MTiO 3 The application in photocatalytic hydrogen production.
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CN110449154A (en) * 2019-07-21 2019-11-15 内蒙古农业大学 A kind of copper oxide and titanium dioxide heterogeneous knot composite catalyst and its preparation method and application
CN112916014A (en) * 2021-01-25 2021-06-08 吉林大学 All-solid-state vector Z mechanism composite photocatalyst CaTiO3/Cu/TiO2Preparation method and application thereof
CN112958061A (en) * 2021-02-04 2021-06-15 青岛科技大学 Oxygen vacancy promoted direct Z mechanism mesoporous Cu2O/TiO2Photocatalyst and preparation method thereof
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