CN114672844B - Preparation method and application of composite material - Google Patents
Preparation method and application of composite material Download PDFInfo
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- CN114672844B CN114672844B CN202210353824.1A CN202210353824A CN114672844B CN 114672844 B CN114672844 B CN 114672844B CN 202210353824 A CN202210353824 A CN 202210353824A CN 114672844 B CN114672844 B CN 114672844B
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- 239000002131 composite material Substances 0.000 title claims abstract description 71
- 238000002360 preparation method Methods 0.000 title abstract description 14
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000001257 hydrogen Substances 0.000 claims abstract description 68
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 68
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 63
- 238000004519 manufacturing process Methods 0.000 claims abstract description 49
- 239000002064 nanoplatelet Substances 0.000 claims abstract description 25
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims abstract description 23
- 239000008367 deionised water Substances 0.000 claims abstract description 23
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 23
- 239000001119 stannous chloride Substances 0.000 claims abstract description 23
- 235000011150 stannous chloride Nutrition 0.000 claims abstract description 23
- 229910002367 SrTiO Inorganic materials 0.000 claims abstract description 22
- 239000001509 sodium citrate Substances 0.000 claims abstract description 15
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical compound [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 claims abstract description 15
- 229940038773 trisodium citrate Drugs 0.000 claims abstract description 15
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 11
- 239000003513 alkali Substances 0.000 claims abstract description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 78
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 60
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 45
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 44
- 239000002135 nanosheet Substances 0.000 claims description 37
- 239000000243 solution Substances 0.000 claims description 36
- 238000000034 method Methods 0.000 claims description 35
- 238000001816 cooling Methods 0.000 claims description 32
- 239000007864 aqueous solution Substances 0.000 claims description 28
- 229910052697 platinum Inorganic materials 0.000 claims description 25
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 24
- 238000001354 calcination Methods 0.000 claims description 24
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 24
- 239000010936 titanium Substances 0.000 claims description 24
- 239000001103 potassium chloride Substances 0.000 claims description 22
- 235000011164 potassium chloride Nutrition 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 21
- 239000002253 acid Substances 0.000 claims description 16
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 15
- 150000004687 hexahydrates Chemical class 0.000 claims description 14
- 229910052724 xenon Inorganic materials 0.000 claims description 14
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 14
- 239000004408 titanium dioxide Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 6
- 150000007529 inorganic bases Chemical class 0.000 claims description 4
- 230000001699 photocatalysis Effects 0.000 abstract description 42
- 230000003197 catalytic effect Effects 0.000 abstract description 12
- 238000011161 development Methods 0.000 abstract description 6
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(ii) oxide Chemical compound [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 abstract 2
- DRIUWMIAOYIBGN-UHFFFAOYSA-N lanthanum titanium Chemical compound [Ti][La] DRIUWMIAOYIBGN-UHFFFAOYSA-N 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 24
- 229910052757 nitrogen Inorganic materials 0.000 description 22
- 229910052593 corundum Inorganic materials 0.000 description 20
- 239000010431 corundum Substances 0.000 description 20
- 238000010438 heat treatment Methods 0.000 description 18
- 239000011259 mixed solution Substances 0.000 description 17
- 239000011941 photocatalyst Substances 0.000 description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 14
- 239000001301 oxygen Substances 0.000 description 14
- 229910052760 oxygen Inorganic materials 0.000 description 14
- 239000003795 chemical substances by application Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 12
- 238000007540 photo-reduction reaction Methods 0.000 description 12
- 230000009467 reduction Effects 0.000 description 12
- 238000006722 reduction reaction Methods 0.000 description 12
- 239000002057 nanoflower Substances 0.000 description 11
- 238000010926 purge Methods 0.000 description 11
- 238000003756 stirring Methods 0.000 description 11
- 238000000227 grinding Methods 0.000 description 10
- 238000001027 hydrothermal synthesis Methods 0.000 description 10
- 239000002060 nanoflake Substances 0.000 description 10
- 238000001291 vacuum drying Methods 0.000 description 10
- 101710179738 6,7-dimethyl-8-ribityllumazine synthase 1 Proteins 0.000 description 9
- 101710186608 Lipoyl synthase 1 Proteins 0.000 description 9
- 101710137584 Lipoyl synthase 1, chloroplastic Proteins 0.000 description 9
- 101710090391 Lipoyl synthase 1, mitochondrial Proteins 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 238000005406 washing Methods 0.000 description 9
- 238000011065 in-situ storage Methods 0.000 description 7
- 230000007935 neutral effect Effects 0.000 description 7
- 238000007146 photocatalysis Methods 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 238000009210 therapy by ultrasound Methods 0.000 description 7
- 241000282326 Felis catus Species 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 238000011068 loading method Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 230000031700 light absorption Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000005121 nitriding Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010335 hydrothermal treatment Methods 0.000 description 2
- 230000004298 light response Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- KPFFMALTIRFAHW-UHFFFAOYSA-N 5-[2-(4-hydroxy-3-methoxyphenyl)ethyl]benzene-1,3-diol Chemical compound C1=C(O)C(OC)=CC(CCC=2C=C(O)C=C(O)C=2)=C1 KPFFMALTIRFAHW-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 239000002159 nanocrystal Substances 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
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- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- JNOLLWPLUCJHQT-UHFFFAOYSA-N tristin Natural products COc1cccc(CCc2cc(O)cc(O)c2)c1 JNOLLWPLUCJHQT-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
- C25B1/04—Hydrogen or oxygen by electrolysis of water
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/50—Processes
- C25B1/55—Photoelectrolysis
Abstract
The invention discloses a preparation method and application of a composite material, which comprises the steps of dissolving stannous chloride and trisodium citrate in deionized water, and then adding LaTiO 2 N two-dimensional nanoplatelets or SrTiO 3 After being dispersed evenly, inorganic alkali solution is added, mixed evenly, and reacted for 10 to 18 hours at 175 to 180 ℃ to obtain the lanthanum titanium oxynitride/stannous oxide composite material. The composite material prepared by the invention has good visible light catalytic hydrogen production performance, and the invention has simple operation and good repeatability. The invention has simple operation and good repeatability, and improves the hydrogen production efficiency and Sn by photocatalytic decomposition of water 3 O 4 Provides a reliable solution for the development and application of (a).
Description
Technical Field
The invention belongs to the field of hydrogen energy preparation, relates to a photocatalysis clean preparation technology of hydrogen energy, and in particular relates to a preparation method and application of a composite material.
Background
With the rapid development of modern society, the energy demand is also increasing. For a long time, the main body of energy consumption is fossil energy such as petroleum and coal, and the use of fossil energy inevitably brings problems of environmental pollution, high carbon emission and the like. As the global carbon budget is depleted, a transition to a lower carbon energy system is imminent. China is used as the largest energy production and consumption country, and the energy structure transformation is also being actively pushed.
The solar energy is abundant in reserve and wide in distribution, and is recognized as the renewable energy source with the most development prospect. However, the difficulties of low energy density, space-time discontinuities, and difficulty in direct storage also greatly limit the large-scale utilization of solar energy. The hydrogen energy is a high-grade energy source, has the advantages of high energy density, cleanness, no carbon, storability and transportation and the like, and is considered as a carrier of future energy sources. Therefore, the conversion of solar energy into hydrogen energy is one of ideal ways to solve the problems of future energy and carbon emission. The solar photocatalytic water splitting hydrogen production can convert solar energy with low energy density and regional change of intensity distribution with time into hydrogen energy with high energy-to-mass ratio and no pollution for storage, and the method has the advantages of simple reaction system, mild reaction condition and low direct investment cost, and is considered as one of the most attractive solar hydrogen production technologies.
The principle of preparing hydrogen by photocatalysis is as follows: the semiconductor photocatalyst absorbs photons with energy larger than the band gap of the photons, and the photons are excited to generate photo-generated electron and hole pairs, then the photo-generated electron and the hole pairs are separated and migrate to the surface of the catalyst, and finally the photo-generated electron and the hole migrating to the active site of the surface of the photocatalyst respectively undergo reduction and oxidation reactions with water to generate hydrogen and oxygen. The development of stable, low-cost, high-efficiency and environment-friendly photocatalyst is still one of the cores of research in the field of photocatalytic water splitting hydrogen production at the present stage.
Among the numerous types of photocatalyst materials that have been reported so far, tristin tetraoxide (Sn 3 O 4 ) The material has the advantages of wide source of raw materials, low cost, easy synthesis, environmental friendliness and the like, more importantly, the material has good visible light response, optical band gap of 2.5eV, light absorption cut-off wavelength of 500nm, proper valence band and conduction band positions, and satisfies thermodynamic conditions of hydrogen production and oxygen production by photocatalysis, and has been paid attention to in the field of photocatalysis in recent years. However, due to its high probability of carrier recombination, its photocatalytic potential is difficult to fully exploit.
Disclosure of Invention
The invention aims to provide a preparation method and application of a composite material, wherein the composite material has a Type-II heterojunction and a three-dimensional hierarchical structure, and can realize high-efficiency photocatalytic hydrogen production of a photocatalyst.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method of preparing a composite material comprising the steps of:
dissolving stannous chloride and trisodium citrate in deionized water, and then adding LaTiO 2 N two-dimensional nanoplatelets or SrTiO 3 After being dispersed evenly, inorganic alkali solution is added, mixed evenly, and reacted for 10 to 18 hours at 175 to 180 ℃ to obtain the composite material.
Further, the ratio of the amounts of stannous chloride and citric acid was 5:12.5.
further, stannous chloride and LaTiO 2 The ratio of the amounts of substances of the N two-dimensional nanoplatelets is 5:0.017-0.17, stannous chloride and SrTiO 3 The ratio of the amounts of the substances is 5:0.017-0.17.
Further, the ratio of stannous chloride to the amount of inorganic base material was 5:2.5.
further, the inorganic base is sodium hydroxide or potassium hydroxide.
Further, laTiO 2 The N two-dimensional nano-sheet is prepared by the following steps:
uniformly mixing lanthanum oxide, titanium dioxide and potassium chloride according to the molar ratio of 1:2:40, calcining at 1000-1100 ℃ for 8-12h, cooling to 500-700 ℃ to obtain La 2 Ti 2 O 7 A nanosheet; la is subjected to 2 Ti 2 O 7 Nano-sheet in NH 3 Calcining at 950-1000deg.C for 10-15h under atmosphere to obtain LaTiO 2 N two-dimensional nanoplatelets.
Further, the temperature is raised to 1000-1100 ℃ at a heating rate of 5-10 ℃/min, the temperature is lowered to 500-700 ℃ at a rate of 40-60 ℃/h, and the temperature is raised to 950-1000 ℃ at a heating rate of 5-10 ℃/min.
The composite material is added into a reactor, and then methanol aqueous solution and hexahydrated chloroplatinic acid aqueous solution are subjected to water decomposition under a xenon lamp to prepare hydrogen.
Further, the dosage ratio of the composite material to the aqueous methanol solution is 20mg:10-20mL.
Further, the mass of platinum in the hexahydrated chloroplatinic acid aqueous solution is 1-3% of the mass of the composite material.
Compared with the prior art, the invention has the beneficial effects that: the invention successfully prepares LaTiO by an in-situ hydrothermal growth method 2 N two-dimensional nanosheets and Sn 3 O 4 Or SrTiO 3 With Sn 3 O 4 Tightly combined to prepare the composite material with the Type-II heterojunction and the three-dimensional hierarchical structure. Sn by in situ hydrothermal growth process 3 O 4 Nanoflower and nanoflakes in situ grown on LaTiO 2 N two-dimensional nanoplatelets or SrTiO 3 On the one hand, the surface can effectively expand Sn 3 O 4 On the other hand, the in-situ growth process can lead to LaTiO 2 N and Sn 3 O 4 Or SrTiO 3 And Sn (Sn) 3 O 4 And close contact is formed between the two components, so that the separation and migration efficiency of carriers is remarkably improved. The catalyst has good visible light catalytic hydrogen production activity after the light reduction of supported Pt, and LaTiO 2 N/Sn 3 O 4 The photocatalysis hydrogen production rate of the composite material can reach 705 mu mol h -1 g cat -1 The quantum efficiency at 400nm was 2.19%, srTiO 3 /Sn 3 O 4 The maximum visible light catalytic hydrogen production rate of the composite material reaches 550 mu mol h -1 g cat -1 Compared with Sn alone 3 O 4 The photocatalytic hydrogen production activity is greatly improved, and the photocatalytic hydrogen production device has good hydrogen production stability. The invention has simple operation and good repeatability, and improves the hydrogen production efficiency and Sn by photocatalytic decomposition of water 3 O 4 Provides a reliable solution for the development and application of (a).
The method of the invention constructs LaTiO with Type-II heterojunction and three-dimensional hierarchical structure for the first time 2 N/Sn 3 O 4 The composite material is cheap and easy to obtain, and the preparation scheme is simple and easy to repeat. Additionally LaTiO 2 N/Sn 3 O 4 The composite material has good visible light catalytic hydrogen production performance.
Drawings
FIG. 1 is LaTiO 2 N、Sn 3 O 4 X-ray diffraction (XRD) patterns for LS-1%, LS-5% and LS-10%.
FIG. 2 is LaTiO 2 N、Sn 3 O 4 And LS-5% Scanning Electron Microscope (SEM) pictures.
FIG. 3 is Sn 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 4 is a Scanning Electron Microscope (SEM) photograph of LS-5%.
FIG. 5 is LaTiO 2 N、Sn 3 O 4 And an ultraviolet-visible absorption spectrum (UV-Vis) diagram of LS-5%.
FIG. 6 is LaTiO 2 K-M relationship diagram of N.
FIG. 7 is Sn 3 O 4 K-M relationship graph of (C).
FIG. 8 is LaTiO 2 N and Sn 3 O 4 Is a mort-schottky (M-S) plot.
FIG. 9 is LaTiO 2 N、Sn 3 O 4 Visible light catalytic hydrogen production rate graphs of L+S-5%, LS-1%, LS-5% and LS-10%.
FIG. 10 shows Sn production during hydrothermal treatment without NaOH 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 11 shows Sn formation at a hydrothermal temperature of 150 ℃ 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 12 shows Sn production at a hydrothermal temperature of 200 ℃ 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 13 shows Sn production at a hydrothermal time of 6h 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 14 shows Sn production at a hydrothermal time of 18h 3 O 4 Scanning Electron Microscope (SEM) photographs of (a).
FIG. 15 is SrTiO 3 、Sn 3 O 4 And SS-10% visible light catalytic hydrogen production rate plot.
Detailed Description
The invention will now be described in detail with reference to specific embodiments thereof in connection with the accompanying drawings.
The invention successfully utilizes the in-situ hydrothermal method to treat Sn 3 O 4 Tightly combined with perovskite (nitrogen) oxide to prepare LaTiO with Type-II heterojunction and three-dimensional hierarchical structure 2 N/Sn 3 O 4 Or SrTiO 3 /Sn 3 O 4 The composite material has good visible light response and higher carrier separation efficiency, and improves Sn 3 O 4 Is beneficial to the industrial application of hydrogen production by photocatalytic decomposition of water. Has good visible light catalytic hydrogen production activity after light reduction and Pt loading, wherein LaTiO 2 N/Sn 3 O 4 The photocatalysis hydrogen production rate of the composite material can reach 705 mu mol h -1 g cat -1 The quantum efficiency at 400nm was 2.19%, srTiO 3 /Sn 3 O 4 The maximum visible light catalytic hydrogen production rate of the composite material reaches 550 mu mol h -1 g cat -1 Compared with Sn alone 3 O 4 The photocatalytic hydrogen production activity is greatly improved, and the photocatalytic hydrogen production device has good hydrogen production stability. The invention has simple operation and good repeatability, and improves the hydrogen production efficiency and Sn by photocatalytic decomposition of water 3 O 4 Provides a reliable solution for the development and application of (a).
LaTiO according to the invention 2 N/Sn 3 O 4 The preparation method of the composite material comprises the following steps:
step one: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30-60min, uniformly mixing, transferring into a corundum crucible, setting a heating program to 5-10 ℃/min, and calcining in a muffle furnace at 1000-1100 ℃ for 8-12h, wherein the nano-sheets grown are smaller due to too short time or too low temperature; then cooling to 500-700 ℃ at the speed of 40-60 ℃/h, and then naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 Placing the nanosheets in a corundum ark, spreading, setting the temperature-raising program to 5-10deg.C/min, and placing the arkWith NH in the open 3 Calcining in a tube furnace at 950-1000 ℃ for 10-15h, NH 3 The flow rate is set to 300-500mL/min, if the temperature is too low or NH 3 Too low a flow rate may lead to insufficient nitriding and inability to prepare pure phase LaTiO 2 N, cooling to room temperature, and collecting to obtain LaTiO 2 N two-dimensional nanoplatelets.
Step two: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are sequentially dissolved in 12.5mL of deionized water, and then 0.017-0.17mmol of LaTiO is added 2 N two-dimensional nanoplatelets or SrTiO 3 Carrying out ultrasonic treatment for 10-30min to uniformly disperse the mixture, finally adding 12.5mL of NaOH solution or KOH solution (0.2 mol/L), stirring for 10min to uniformly mix the mixture, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the mixed solution for 10-18h in a baking oven at 175-180 ℃; excessive temperature or time may lead to Sn 3 O 4 The nanometer petals are too thick and even are piled up into blocks, and the Sn can be caused by too low temperature or short time 3 O 4 The growth of the nanoflower is incomplete; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain powdery LaTiO 2 N/Sn 3 O 4 Composite or SrTiO 3 /Sn 3 O 4 A composite material. According to LaTiO in composite material 2 N or SrTiO 3 And Sn 3 O 4 The ratio x% of the amount of substance is designated LS-x% or SS-x%, respectively.
Step three: and (3) adding the LS-x% or SS-x% composite material prepared in the step (II) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test of preparing hydrogen by photocatalytic water splitting by a photo-reduction method with platinum (1 wt% of platinum). The method comprises the following specific steps:
20mg of LS-x% or SS-x% composite material is added into a reactor with the volume of 250mL, and a methanol aqueous solution with the methanol content of 10-20vol% and the total volume of 100mL is added as a sacrificial agent (other sacrificial agents have no effect as compared with methanol); and adding an aqueous solution of chloroplatinic acid hexahydrate (the mass of Pt is 1-3wt% compared with the mass of LS-x% or SS-x% composite material); then introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; and then turning on a magnetic stirrer, and carrying out photoreduction for 15-30min by using a 300W xenon lamp light source to load the cocatalyst Pt.
Example 1
Step 1: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, calcining for 10h at 1000 ℃ in a muffle furnace, setting a heating program to 5 ℃/min, cooling to 700 ℃ according to a speed of 50 ℃/h, and naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheets are placed in a corundum ark for paving, and the ark is placed in a state that NH is introduced 3 Calcining at 1000deg.C for 15 hr, heating to 5 deg.C/min, and NH 3 The flow rate is set to 500mL/min, and the LaTiO is obtained after cooling to room temperature and collecting 2 N two-dimensional nanoplatelets.
Step 2: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.017mmol of LaTiO is added 2 N, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min, after uniformly mixing the solution, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the mixed solution for 12h in a 175 ℃ oven; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain 1 percent LaTiO 2 N/Sn 3 O 4 The composite sample was named LS-1%.
Step 3: and (3) adding the LS-1% composite sample prepared in the step (2) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test of preparing hydrogen by photocatalytic water splitting by a photo-reduction method and loading platinum (1 wt% of platinum). The method comprises the following specific steps:
a reactor having a volume of 250mL was charged with 20mg of LS-1% photocatalyst, and an aqueous solution having a methanol concentration of 10vol% was added as a sacrificial agent in a total volume of 100 mL; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Example 2
Step 1: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, calcining for 10h at 1000 ℃ in a muffle furnace, setting a heating program to 5 ℃/min, cooling to 700 ℃ according to a speed of 50 ℃/h, and naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheets are placed in a corundum ark for paving, and the ark is placed in a state that NH is introduced 3 Calcining at 1000deg.C for 15 hr, heating to 5 deg.C/min, and NH 3 The flow rate is set to 500mL/min, and the LaTiO is obtained after cooling to room temperature and collecting 2 N two-dimensional nanoplatelets.
Step 2: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.083mmol of LaTiO is added 2 N, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min, after uniformly mixing the solution, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the mixed solution for 12h in a 175 ℃ oven; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain 5 percent LaTiO 2 N/Sn 3 O 4 Composite samples were named LS-5%.
Step 3: and (3) adding the LS-5% composite sample prepared in the step (2) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test of preparing hydrogen by photocatalytic water splitting by a photo-reduction method and loading platinum (1 wt% of platinum). The method comprises the following specific steps:
a reactor with a volume of 250mL is charged with 20mg LS-5% photocatalyst and an aqueous solution with a total volume of 100mL and a methanol concentration of 10vol% is added as a sacrificial agent; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Example 3
Step 1: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, calcining for 10h at 1000 ℃ in a muffle furnace, setting a heating program to 5 ℃/min, cooling to 700 ℃ according to a speed of 50 ℃/h, and naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheets are placed in a corundum ark for paving, and the ark is placed in a state that NH is introduced 3 Calcining at 1000deg.C for 15 hr, heating to 5 deg.C/min, and NH 3 The flow rate is set to 500mL/min, and the LaTiO is obtained after cooling to room temperature and collecting 2 N two-dimensional nanoplatelets.
Step 2: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.17mmol of LaTiO is added 2 N, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min, after uniformly mixing the solution, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the mixed solution for 12h in a 175 ℃ oven; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain 10 percent of LaTiO 2 N/Sn 3 O 4 Composite samples were named LS-10%.
Step 3: and (3) adding the LS-10% composite sample prepared in the step (2) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test of preparing hydrogen by photocatalytic water splitting by a photo-reduction method and loading platinum (1 wt% of platinum). The method comprises the following specific steps:
20mg of LS-10% photocatalyst is added into a reactor with the volume of 250mL, and an aqueous solution with the total volume of 100mL and the methanol concentration of 10vol% is added as a sacrificial agent; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Example 4
Step 1: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.17mmol of SrTiO is added 3 Carrying out ultrasonic treatment for 10min to uniformly disperse the mixed solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min, and transferring the mixed solution into a 100mL hydrothermal kettle and heating the mixed solution for 12h in a 175 ℃ oven; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain 10 percent SrTiO 3 /Sn 3 O 4 The composite material was named SS-10%.
Step 2: and (3) adding the SS-10% composite material prepared in the step (1) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test for preparing hydrogen by photocatalytic water splitting by a photo-reduction method with platinum (with 1wt% of platinum). The method comprises the following specific steps:
20mg of SS-10% composite material was charged into a reactor having a volume of 250mL, and an aqueous solution having a methanol concentration of 10vol% was added as a sacrificial agent in a total volume of 100 mL; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Example 5
LaTiO according to the invention 2 N/Sn 3 O 4 The preparation method of the composite material comprises the following steps:
step one: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, setting a heating program to 10 ℃/min, and calcining in a muffle furnace at 1000 ℃ for 12h, wherein the nano-sheets grown are smaller due to too short time or too low temperature; then cooling to 700 ℃ at a speed of 60 ℃/h, and then naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 Placing the nanosheets in a corundum ark for paving, setting the temperature-raising program to 8 ℃/min, and placing the ark in a state that NH is introduced 3 Calcining at 1000 ℃ in a tube furnaceBurn for 10h, NH 3 The flow rate is set to 500mL/min, if the temperature is too low or NH 3 Too low a flow rate may lead to insufficient nitriding and inability to prepare pure phase LaTiO 2 N, cooling to room temperature, and collecting to obtain LaTiO 2 N two-dimensional nanoplatelets.
Step two: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.08mmol of LaTiO is added 2 N two-dimensional nanoplatelets or SrTiO 3 Ultrasonic treating for 10min to disperse uniformly, adding 12.5mL NaOH solution (0.2 mol/L), stirring for 10min, mixing uniformly, transferring the mixed solution into 100mL hydrothermal kettle, and heating in 178 deg.C oven for 15 hr to obtain powdered LaTiO 2 N/Sn 3 O 4 A composite material.
Step three: into a reactor having a volume of 250mL, 20mg of LaTiO was added 2 N/Sn 3 O 4 Adding a methanol aqueous solution with the methanol content of 10vol% into the composite material, wherein the total volume of the methanol aqueous solution is 100mL, and the methanol aqueous solution is taken as a sacrificial agent; and adding aqueous chloroplatinic acid hexahydrate (Pt mass compared with LaTiO) 2 N/Sn 3 O 4 The mass of the composite material is 1 wt%; then introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; and then the magnetic stirrer is started, and a 300W xenon lamp light source is used for light reduction for 15min.
Example 6
LaTiO according to the invention 2 N/Sn 3 O 4 The preparation method of the composite material comprises the following steps:
step one: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 60min, uniformly mixing, transferring into a corundum crucible, setting a heating program to 5 ℃/min, and calcining in a muffle furnace at 1100 ℃ for 8h, wherein the nano-sheets grown are smaller due to too short time or too low temperature; then cooling to 500 ℃ at a speed of 50 ℃/h, and then naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheet is placed in a corundum ark to be laid flatSetting the temperature-raising program at 7 deg.c/min, setting the ark with NH 3 Calcining at 950 ℃ for 15h and NH in a tube furnace of (C) 3 The flow rate is set to 500mL/min, if the temperature is too low or NH 3 Too low a flow rate may lead to insufficient nitriding and inability to prepare pure phase LaTiO 2 N, cooling to room temperature, and collecting to obtain LaTiO 2 N two-dimensional nanoplatelets.
Step two: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.1mmol of LaTiO is added 2 N two-dimensional nanoplatelets or SrTiO 3 Ultrasonic treating for 30min to disperse uniformly, adding 12.5mL NaOH solution (0.2 mol/L), stirring for 10min, mixing uniformly, transferring the mixed solution into 100mL hydrothermal kettle, and heating in oven at 180deg.C for 12 hr to obtain powdered LaTiO 2 N/Sn 3 O 4 A composite material.
Step three: into a reactor having a volume of 250mL, 20mg of LaTiO was added 2 N/Sn 3 O 4 Adding a methanol aqueous solution with the total volume of 100mL and the methanol content of 20vol% as a sacrificial agent into the composite material; and adding aqueous chloroplatinic acid hexahydrate (Pt mass compared with LaTiO) 2 N/Sn 3 O 4 The mass of the composite material is 2 wt%; then introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; the magnetic stirrer was turned on again, and photo-reduction was performed for 30min using a 300W xenon lamp light source to support the cocatalyst Pt.
Example 7
LaTiO according to the invention 2 N/Sn 3 O 4 The preparation method of the composite material comprises the following steps:
step one: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 40min, uniformly mixing, transferring into a corundum crucible, setting a heating program to 7 ℃/min, and calcining in a muffle furnace at 1050 ℃ for 10h, wherein the nano-sheets grown are smaller due to too short time or too low temperature; then cooling to 600 ℃ at a speed of 40 ℃/h, and then naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 Placing the nanosheets in a corundum ark for paving, setting the temperature-raising program to 10 ℃/min, and placing the ark in a state that NH is introduced 3 Calcining at 970 deg.c for 12 hr, NH 3 The flow rate is set to 400mL/min, if the temperature is too low or NH 3 Too low a flow rate may lead to insufficient nitriding and inability to prepare pure phase LaTiO 2 N, cooling to room temperature, and collecting to obtain LaTiO 2 N two-dimensional nanoplatelets.
Step two: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are sequentially dissolved in 12.5mL of deionized water, and then 0.051mmol of LaTiO is added 2 N two-dimensional nanoplatelets or SrTiO 3 Ultrasonic treating for 20min to disperse uniformly, adding 12.5mL KOH solution (0.2 mol/L), stirring for 10min, mixing uniformly, transferring the mixed solution into 100mL hydrothermal kettle, and heating in 175 deg.C oven for 18 hr to obtain powdered LaTiO 2 N/Sn 3 O 4 A composite material.
Step three: into a reactor having a volume of 250mL, 20mg of LaTiO was added 2 N/Sn 3 O 4 Adding a methanol aqueous solution with the methanol content of 10vol% into the composite material, wherein the total volume of the methanol aqueous solution is 100mL, and the methanol aqueous solution is taken as a sacrificial agent; and adding aqueous chloroplatinic acid hexahydrate (Pt mass compared with LaTiO) 2 N/Sn 3 O 4 The mass of the composite material is 3 wt%; then introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; the magnetic stirrer was turned on again, and photo-reduction was performed using a 300W xenon lamp light source for 20min to support the cocatalyst Pt.
Example 8
LaTiO according to the invention 2 N/Sn 3 O 4 The preparation method of the composite material comprises the following steps:
step one: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 50min, uniformly mixing, transferring into a corundum crucible, setting a heating program to 8 ℃/min, and calcining in a muffle furnace at 1070 ℃ for 9h, wherein the short time or the low temperature can lead to the growth of a small nano sheet; then cooling to 650 ℃ at a rate of 45 ℃/h, and then naturally cooling; using a large amount of deionized waterWashing the sample to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 Placing the nanosheets in a corundum ark for paving, setting the temperature-raising program to 10 ℃/min, and placing the ark in a state that NH is introduced 3 Calcining at 980 ℃ for 11h and NH in a tube furnace 3 The flow rate is set to 350mL/min, if the temperature is too low or NH 3 Too low a flow rate may lead to insufficient nitriding and inability to prepare pure phase LaTiO 2 N, cooling to room temperature, and collecting to obtain LaTiO 2 N two-dimensional nanoplatelets.
Step two: 5mmol of stannous chloride and 12.5mmol of trisodium citrate are dissolved in 12.5mL of deionized water in sequence, and then 0.034mmol of LaTiO is added 2 N two-dimensional nanoplatelets or SrTiO 3 Ultrasonic treating for 10min to disperse uniformly, adding 12.5mL KOH solution (0.2 mol/L), stirring for 10min, mixing uniformly, transferring the mixed solution into 100mL hydrothermal kettle, and heating in oven at 180deg.C for 18 hr to obtain powdered LaTiO 2 N/Sn 3 O 4 A composite material.
Step three: into a reactor having a volume of 250mL, 20mg of LaTiO was added 2 N/Sn 3 O 4 Adding a methanol aqueous solution with a total volume of 100mL and a methanol content of 15vol% as a sacrificial agent into the composite material; and adding aqueous chloroplatinic acid hexahydrate (Pt mass compared with LaTiO) 2 N/Sn 3 O 4 The mass of the composite material is 1 wt%; then introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; and then the magnetic stirrer is started, and a 300W xenon lamp light source is used for light reduction for 30min.
Comparative example 1
Step 1: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, calcining for 10h at 1000 ℃ in a muffle furnace, setting a heating program to 5 ℃/min, cooling to 700 ℃ according to a speed of 50 ℃/h, and naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheets are placed in a corundum ark for paving, and the ark is placed in a state that NH is introduced 3 Calcining at 1000deg.C for 15 hr, heating to 5 deg.C/min, and NH 3 The flow rate is set to 500mL/min, and the LaTiO is obtained after cooling to room temperature and collecting 2 N two-dimensional nanoplatelets.
Step 2: laTiO prepared in step 1 2 And adding N powder into a reaction system for preparing hydrogen by photocatalytic water decomposition, and carrying out a test for preparing hydrogen by photocatalytic water decomposition by a photo-reduction method by loading platinum (1 wt% of platinum). The method comprises the following specific steps:
into a reactor having a volume of 250mL, 20mg of LaTiO was added 2 N photocatalyst, adding a 10vol% methanol aqueous solution with the total volume of 100mL as a sacrificial agent; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Comparative example 2
Step 1: sequentially dissolving 5mmol of stannous chloride and 12.5mmol of trisodium citrate in 12.5mL of deionized water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min to uniformly mix the solution, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the solution in an oven at 175 ℃ for 12h; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain Sn 3 O 4 And (3) powder.
Step 2: sn prepared in step 1 3 O 4 The powder is added into a reaction system for preparing hydrogen by photocatalytic water decomposition, and platinum (1 wt% of platinum is loaded) is loaded by a photo-reduction method to perform a test for preparing hydrogen by photocatalytic water decomposition. The method comprises the following specific steps:
into a reactor having a volume of 250mL, 20mg of Sn was charged 3 O 4 A photocatalyst, adding a total volume of 100mL of aqueous solution with methanol concentration of 10vol% as a sacrificial agent; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; to the reactorPurging with nitrogen for 15min to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
Comparative example 3
Step 1: grinding lanthanum oxide, titanium dioxide and potassium chloride according to a molar ratio of 1:2:40 for 30min, uniformly mixing, transferring into a corundum crucible, calcining for 10h at 1000 ℃ in a muffle furnace, setting a heating program to 5 ℃/min, cooling to 700 ℃ according to a speed of 50 ℃/h, and naturally cooling; washing the sample with a large amount of deionized water to remove residual potassium chloride, and vacuum drying and collecting the sample to obtain La 2 Ti 2 O 7 A nanosheet; taking 0.5g of prepared La 2 Ti 2 O 7 The nano-sheets are placed in a corundum ark for paving, and the ark is placed in a state that NH is introduced 3 Calcining at 1000deg.C for 15 hr, heating to 5 deg.C/min, and NH 3 The flow rate is set to 500mL/min, and the LaTiO is obtained after cooling to room temperature and collecting 2 N two-dimensional nanoplatelets.
Step 2: sequentially dissolving 5mmol of stannous chloride and 12.5mmol of trisodium citrate in 12.5mL of deionized water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, finally adding 12.5mL of NaOH solution (0.2 mol/L), stirring for 10min to uniformly mix the solution, transferring the mixed solution into a 100mL hydrothermal kettle, and heating the solution in an oven at 175 ℃ for 12h; after the water is naturally cooled, the water is centrifugally washed to be neutral; finally, the sample is dried and collected in vacuum to obtain Sn 3 O 4 And (3) powder.
Step 3: laTiO prepared in step 1 2 N powder and Sn prepared in step 2 3 O 4 The powder was milled for 30min at a 1:20 molar ratio to allow for physical mixing to be uniform, designated as L+S-5%.
Step 4: and (3) adding the L+S-5% powder prepared in the step (3) into a reaction system for preparing hydrogen by photocatalytic water splitting, and carrying out a test for preparing hydrogen by photocatalytic water splitting by a photo-reduction method and loading platinum (1 wt% of platinum). The method comprises the following specific steps:
20mg of L+S-5% photocatalyst is added into a reactor with the volume of 250mL, and an aqueous solution with the total volume of 100mL and the methanol concentration of 10vol% is added as a sacrificial agent; and 0.237mL of an aqueous solution of chloroplatinic acid hexahydrate having a platinum content of 0.8444mg/mL was added; introducing nitrogen into the reactor to purge for 15min so as to remove oxygen in the system; then the magnetic stirrer is started, and the xenon lamp power supply is started to carry out light reduction for 15min.
In summary, examples 1-3 gave LS-1%, LS-5% and LS-10% photocatalyst, respectively, and comparative examples 1-3 gave LaTiO, respectively 2 N、Sn 3 O 4 And L+S-5% photocatalyst, and carrying out photoreduction platinum-carrying and visible light decomposition water hydrogen production test on the 6 photocatalysts respectively.
FIG. 1 is LaTiO 2 N、Sn 3 O 4 X-ray diffraction (XRD) patterns of LS-1%, LS-5% and LS-10%, wherein LaTiO 2 The diffraction peak of N belongs to a typical orthorhombic crystal structure (JCPDS No. 00-048-1230); sn (Sn) 3 O 4 Has a typical triclinic phase crystal structure (JCPDS No. 00-016-0737); whereas LS-5% and LS-10% of the composite sample have LaTiO at the same time 2 N and Sn 3 O 4 Shows that the LaTiO is successfully prepared by a molten salt-hydrothermal method 2 N/Sn 3 O 4 Composite material, it should be noted that no LaTiO was detected in LS-1% of the samples 2 Diffraction peaks for N due to LaTiO 2 The N content is too low.
FIGS. 2, 3 and 4 are LaTiO 2 N、Sn 3 O 4 And LS-5% Scanning Electron Microscope (SEM) photograph, laTiO 2 N is mainly composed of two-dimensional nano-sheets which are several micrometers long and hundreds of nanometers wide; and Sn is 3 O 4 Then has a hierarchical structure of nanoflower shape, which is built up from nano-platelets of hundreds of nanometers in size; for LS-5% composite samples, laTiO can be seen 2 The surface of the N nano-sheet is coated with Sn 3 O 4 Nanoflower and nanoflake coating, partial Sn 3 O 4 Nanoflakes even embedded in LaTiO 2 N nanosheet surface, indicating that hydrothermal treatment can treat LaTiO 2 N two-dimensional nanoplatelets and Sn 3 O 4 The nanoflower and the nano sheet are tightly combined together to successfully construct the LaTiO with the three-dimensional hierarchical structure 2 N/Sn 3 O 4 And a heterojunction.
FIGS. 5, 6 and 7 are LaTiO 2 N、Sn 3 O 4 And LS-5% ultraviolet-visible absorption spectrum (UV-vis) and K-M relationship, laTiO 2 The light absorption cut-off wavelength of N is about 600nm, and the corresponding band gap is calculated to be-2.15 eV according to a K-M relation diagram; and Sn is 3 O 4 The light absorption cut-off wavelength of the light source is about 500nm, and the corresponding band gap is calculated to be-2.50 eV according to a K-M relation diagram; while LS-5% of the composite sample has a light absorption cut-off wavelength of LaTiO 2 N and Sn 3 O 4 Between them, explain LaTiO 2 The introduction of N can effectively expand Sn 3 O 4 Is a light absorption range of (a).
FIG. 8 is LaTiO 2 N and Sn 3 O 4 Is shown by the Mott-Schottky (M-S) graph of LaTiO 2 N and Sn 3 O 4 All have n-type semiconductor characteristics, and LaTiO 2 N and Sn 3 O 4 The flatband potentials of (C) were at-0.35V and-0.12V (vs RHE), respectively, and they revealed that LaTiO 2 The conduction band bottom position of N is compared with Sn 3 O 4 Is 0.23eV higher than the conduction band bottom; calculation of LaTiO by combining the K-M relationship diagram in FIGS. 6 and 7 2 N and Sn 3 O 4 The optical band gap of (2.15 eV and 2.50eV, respectively), can be deduced that Sn 3 O 4 The valence band peak position of (C) is compared with LaTiO 2 The valence band top position of N is 0.59eV lower. Thus, it can be deduced that LaTiO 2 N and Sn 3 O 4 A type-ii band structure is formed.
FIG. 9 is LaTiO 2 N、Sn 3 O 4 Visible light catalytic hydrogen production rate diagram of L+S-5%, LS-1%, LS-5% and LS-10%, single Sn 3 O 4 The hydrogen production rate under the irradiation of visible light is 284 mu mol h -1 g -1 Single LaTiO 2 The hydrogen production rate of N under the irradiation of visible light is only 17 mu mol h -1 g -1 The method comprises the steps of carrying out a first treatment on the surface of the LaTiO is prepared by a hydrothermal method 2 N and Sn 3 O 4 After the combination, the photocatalytic hydrogen production activity of the sample is obviously improved, wherein the visible light catalytic hydrogen production rate of the LS-5% composite photocatalyst is up to 705 mu mol h -1 g cat -1 At 400Apparent quantum efficiency measured at nm was 2.19%, which is single Sn 3 O 4 And LaTiO 2 2.5 times and 41 times of N photocatalysis hydrogen production activity; notably, the L+S-5% comparison sample prepared by the physical mixing method is subjected to hydrogen production half reaction under the same condition, and the photocatalytic hydrogen production rate is 321 mu mol h -1 g -1 Slightly higher than pure Sn 3 O 4 Illustrating LaTiO by photocatalytic hydrogen production rate 2 The introduction of N can indeed promote Sn 3 O 4 Is a hydrogen-producing activity of (a); however, the activity was far lower than that of LS-4% samples prepared by hydrothermal method, indicating that LaTiO prepared by hydrothermal method 2 N/Sn 3 O 4 The close contact is formed between the composite samples, which plays a key role in improving the photocatalytic activity. In addition, in the case of the optical fiber,
FIG. 15 is SrTiO 3 、Sn 3 O 4 And SS-10% visible light catalytic hydrogen production rate plot, single Sn 3 O 4 The hydrogen production rate under the irradiation of visible light is 284 mu mol h -1 g -1 While SrTiO 3 Limited by the wider band gap, the visible light cannot be utilized, and the hydrogen production rate is only 3 mu mol h -1 g -1 The method comprises the steps of carrying out a first treatment on the surface of the SrTiO is prepared by in-situ hydrothermal process 3 And Sn (Sn) 3 O 4 After compounding, the photocatalytic hydrogen production activity of the sample is obviously improved, and the visible light catalytic hydrogen production rate of the SS-10% compound photocatalyst is up to 550 mu mol h -1 g cat -1 Is single Sn 3 O 4 1.9 times of the photocatalytic hydrogen production activity, which shows that the in-situ hydrothermal growth process adopted in the invention is carried out on Sn 3 O 4 ABX is introduced into the surface of (C) 3 Perovskite (nitrogen) oxide for enhanced Sn 3 O 4 The photocatalytic hydrogen production activity of the catalyst is universal.
It should be noted that the hydrothermal process of the present invention mainly grows Sn 3 O 4 The process of nanoflower and nanoflakes, the preparation conditions in the hydrothermal process such as acid-base, hydrothermal time and hydrothermal temperature, etc. are specific to Sn 3 O 4 And the final composite material has a larger influence on morphology and performance. The following Sn under different conditions 3 O 4 The morphology of (c) is exemplified and the influence of each factor is analyzed.
First, as shown in FIG. 10, when NaOH is not added to the reaction solution, hydrolysis of stannous chloride causes the solution to be acidic and Sn is formed 3 O 4 Presenting a stacked particle, rather than nanoflower and nanoflake morphology; FIG. 3 shows the Sn produced when NaOH solution is added 3 O 4 The nanometer flower and nanometer flake are in shape, mainly because the NaOH solution mainly plays a role of mineralizer in the hydrothermal reaction process, and can promote Sn 3 O 4 And (3) generating nano-flakes.
Next, as shown in FIG. 11, when the hydrothermal temperature is 150 ℃, only a small amount of Sn is observed 3 O 4 Nanoflower and nanoflakes, most Sn 3 O 4 Still in the form of particles, indicating that the reaction temperature is insufficient to grow all of the Sn element into Sn 3 O 4 Nanoflowers and nanoflakes; and when the hydrothermal temperature is 200 ℃, sn 3 O 4 Then the nano-bulk morphology is exhibited, and as shown in FIG. 12, it is estimated that the temperature is too high and Sn 3 O 4 The growth of nanocrystals occurs faster and packing occurs.
Finally, for the hydrothermal time, as shown in FIG. 13, when the hydrothermal time is too short (6 h), sn 3 O 4 Incomplete growth of nanoflowers and nanoflakes; when the hydrothermal time is too long (18 h), sn 3 O 4 The nanoflowers and nanoflakes may be too thick in size, as shown in fig. 14, which is detrimental to their subsequent and LaTiO counterparts 2 And compounding the N two-dimensional nano-sheets.
Claims (10)
1. A method of preparing a composite material, comprising the steps of:
dissolving stannous chloride and trisodium citrate in deionized water, and then adding LaTiO 2 N two-dimensional nanoplatelets or SrTiO 3 After being dispersed evenly, inorganic alkali solution is added, mixed evenly, and reacted for 10 to 18 hours at 175 to 180 ℃ to obtain the composite material.
2. The method for preparing a composite material according to claim 1, wherein the ratio of the amounts of stannous chloride and trisodium citrate is 5:12.5.
3. the method for preparing a composite material according to claim 1, wherein stannous chloride and LaTiO 2 The ratio of the amounts of substances of the N two-dimensional nanoplatelets is 5:0.017-0.17, stannous chloride and SrTiO 3 The ratio of the amounts of the substances is 5:0.017-0.17.
4. The method for preparing a composite material according to claim 1, wherein the ratio of stannous chloride to the amount of inorganic base substance is 5:2.5.
5. the method of claim 1, wherein the inorganic base is sodium hydroxide or potassium hydroxide.
6. The method for preparing a composite material according to claim 1, wherein the LaTiO 2 The N two-dimensional nano-sheet is prepared by the following steps:
uniformly mixing lanthanum oxide, titanium dioxide and potassium chloride according to the molar ratio of 1:2:40, calcining at 1000-1100 ℃ for 8-12h, cooling to 500-700 ℃ to obtain La 2 Ti 2 O 7 A nanosheet; la is subjected to 2 Ti 2 O 7 Nano-sheet in NH 3 Calcining at 950-1000deg.C for 10-15h under atmosphere to obtain LaTiO 2 N two-dimensional nanoplatelets.
7. The method of preparing a composite material according to claim 6, wherein the temperature is raised to 1000-1100 ℃ at a temperature raising rate of 5-10 ℃/min, the temperature is lowered to 500-700 ℃ at a rate of 40-60 ℃/h, and the temperature is raised to 950-1000 ℃ at a temperature raising rate of 5-10 ℃/min.
8. Use of a composite material prepared according to the method of any one of claims 1 to 7, wherein the composite material is fed into a reactor, and then an aqueous methanol solution and an aqueous chloroplatinic acid hexahydrate solution are subjected to hydrogen production by decomposition of water under a xenon lamp.
9. The use according to claim 8, wherein the ratio of the composite material to the aqueous methanol solution is 20mg:10-20mL.
10. Use according to claim 8, characterized in that the mass of platinum in the aqueous solution of chloroplatinic acid hexahydrate is 1-3% of the mass of the composite material.
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