Preparation method of co-doped titanium oxide photocatalyst for hydrogen production by photolysis of water and product prepared by preparation method

Abstract

The invention discloses a preparation method of a co-doped titanium oxide photocatalyst for hydrogen production through water photolysis and a product prepared through the preparation method, TiCl4 and magnesium nitride are used as raw materials, the co-doped MgCO3 / C-N-TiO2 nano titanium oxide photocatalyst is formed by adjusting the molar ratio of N < 3-> to Ti < 4 + > and conducting carbon doping, the photocatalytic hydrogen production performance of TiO2 is effectively improved, and the photocatalytic hydrogen production efficiency is improved. The hydrogen evolution performance can reach 2-3 mmol / g.h under the irradiation of a 300W xenon lamp, a new way is provided for preparation of a co-doped anatase titanium oxide photocatalyst, and the industrial requirement of photocatalytic hydrogen production of a titanium oxide material can be well met.

Description

Technical Field

[0001] The invention relates to the technical field of nano photocatalyst materials, and in particular to a method for preparing a doped titanium oxide photocatalyst for producing hydrogen through photolysis of water and a product obtained therefrom. Background Art

[0002] Titanium dioxide (TiO2) is an important new energy and environmental protection material, which can be used in photocatalysis, solar power generation, environmental protection and other fields. However, wide bandgap TiO2 materials have problems such as narrow light absorption range and low separation efficiency of electron-hole pairs, which seriously limit their practical applications. Research results show that doping TiO2 with non-metallic ions such as H, C, and N can effectively narrow its bandgap width, especially when H is doped into titanium oxide at a certain concentration, it can turn titanium oxide black and make its absorption rate of visible light reach more than 80%. However, this H-doped titanium oxide has the disadvantages of poor chemical stability and easy oxidation, which makes it difficult to meet the requirements of efficient solar hydrogen production.

[0003] At present, the existing technology for the preparation of N-doped titanium oxide mainly includes high-temperature ammonia diffusion and high-temperature nitrogen precursor diffusion, such as using ammonia or dimethyl imidazole as a nitrogen source to achieve N-doped titanium oxide at high temperature. However, this high-temperature diffusion method for achieving N-doping is prone to produce interstitial N-doping, which is very unfavorable to the photocatalytic performance of titanium oxide (the more N doping, the worse the photocatalytic water splitting hydrogen evolution performance). How to achieve high-doping, substitutional N-doped titanium oxide materials and improve their photocatalytic water splitting hydrogen evolution performance has always been a difficulty in the field of photochemistry. Research results show that (C, N) co-doping can improve the photocatalytic oxidation performance of titanium oxide materials, but does not significantly improve their photocatalytic reduction performance. For this reason, the existing technology still cannot meet the industrial demand for photocatalytic hydrogen production from titanium oxide materials. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a co-doped titanium oxide photocatalyst for photocatalytic water splitting to produce hydrogen, so as to obtain a high-doping, substituted N-doped titanium oxide photocatalyst, thereby effectively improving the photocatalytic hydrogen production performance of TiO2, and providing a new way for the preparation of co-doped anatase titanium oxide photocatalyst to meet the industrial demand for photocatalytic hydrogen production of titanium oxide materials. Another purpose of the present invention is to provide a product prepared by the above preparation method.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for preparing a co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen, comprising the following steps:

[0007] (1) Preparation of reaction product solution

[0008] According to the molar ratio n(N 3- )∶n(Ti 4+ )=0.1~1:1, adding TiCl4 and magnesium nitride (Mg3N2) into a toluene solution, and performing a solvent thermal reaction at 160~200° C. in a reaction kettle for 8~12 hours to obtain a reaction product solution;

[0009] (2) Preparation of precursor precipitate

[0010] According to the molar ratio n(NH4 + )∶n(Ti 4+ )=3~5:1, add the reaction product solution into an aqueous solution of ammonium bicarbonate with a concentration of 1 mol / L, and stir and hydrolyze at a pH value of 7~8 to make Ti 4+ Mg 2+ They were all transformed into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively, and after washing, a yellow precursor precipitate was obtained;

[0011] (3) Calcination treatment of precursor precipitate

[0012] According to the molar ratio n(C6H 12 O6)∶n(Ti 4+ )=0.01~0.1:1, add carbon-doped precursor glucose to the precursor precipitate, and then calcine it in an argon atmosphere, the calcination temperature is 350~400℃, the insulation time is 1~2h, and after cooling, a red, co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst is obtained.

[0013] The product is prepared by the method for preparing the co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst for hydrogen production by photolysis. 3- )∶n(Ti 4+ )=0.1~1∶1、n(C 4+ )∶n(Ti 4+ )=0.06~0.12:1. The nano titanium oxide photocatalyst has a nearly spherical particle shape and a particle size of 10~20nm.

[0014] The present invention has the following beneficial effects:

[0015] The present invention adopts solvent thermal method to assist heat treatment to prepare co-doped nano titanium oxide photocatalyst. 3- / Ti 4+The molar ratio of MgCO3 / CN-TiO2 forms a high-doping, substitutional N-doped nano-titanium oxide powder. The prepared MgCO3 / CN-TiO2 powder is red and anatase phase, which can effectively improve the photocatalytic hydrogen production performance of TiO2. The hydrogen evolution performance reaches 2-3mmol / gh under 300W xenon light irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings:

[0017] Figure 1 is an X-ray crystal diffraction pattern of the co-doped titanium oxide photocatalyst prepared in the embodiments of the present invention (sample 1 is embodiment 1, sample 2 is embodiment 2, and sample 3 is embodiment 3);

[0018] Figure 2 It is a transmission electron microscope image of the co-doped titanium oxide photocatalyst prepared in the embodiments of the present invention (sample 1 is embodiment 1, sample 2 is embodiment 2, and sample 3 is embodiment 3);

[0019] Figure 3 This is a transmission electron microscope micro-area element distribution diagram of the co-doped titanium oxide photocatalyst prepared in Example 1 of the present invention;

[0020] Figure 4 It is a comparison chart of the UV-visible absorption spectra of the co-doped titanium oxide photocatalyst prepared in the embodiments of the present invention and the commercial P25 powder (sample 1 is embodiment 1, sample 2 is embodiment 2, and sample 3 is embodiment 3);

[0021] Figure 5 It is the performance of photocatalytic water splitting and hydrogen evolution of the co-doped titanium oxide photocatalyst prepared in the embodiments of the present invention (sample 1 is embodiment 1, sample 2 is embodiment 2, and sample 3 is embodiment 3). DETAILED DESCRIPTION

[0022] Embodiment 1:

[0023] This embodiment provides a method for preparing a co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen, and the steps are as follows:

[0024] (1) Preparation of reaction product solution

[0025] 19.1 g TiCl4 (0.1 mol) and 3.3 g magnesium nitride (0.033 mol) were added to 200 ml toluene solution, and the mixture was subjected to solvent thermal reaction at 200° C. for 12 h in a reaction vessel to obtain a reaction product solution;

[0026] (2) Preparation of precursor precipitate

[0027] The above reaction product solution was added into 400 ml of 1 mol / L ammonium bicarbonate aqueous solution and stirred for hydrolysis reaction at pH 7-8 to make Ti 4+ Mg 2+ They were all transformed into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively, and after repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained;

[0028] (3) Calcination treatment of precursor precipitate

[0029] 0.3 g of carbon-doped precursor glucose was added to the above precursor precipitate, and then calcined in an argon atmosphere at a temperature of 380° C. for 2 h. After cooling, a red co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst was obtained.

[0030] Embodiment 2:

[0031] This embodiment provides a method for preparing a co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen, and the steps are as follows:

[0032] (1) Preparation of reaction product solution

[0033] 19.1 g TiCl4 (0.1 mol) and 5 g magnesium nitride (0.05 mol) were added to 200 ml toluene solution, and the mixture was subjected to solvent thermal reaction at 200°C for 12 h in a reaction vessel to obtain a reaction product solution;

[0034] (2) Preparation of precursor precipitate

[0035] The above reaction product solution was added into 400 ml of 1 mol / L ammonium bicarbonate aqueous solution and stirred for hydrolysis reaction at pH 7-8 to make Ti 4+ Mg 2+ They were all transformed into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively, and after repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained;

[0036] (3) Calcination treatment of precursor precipitate

[0037] 0.3 g of carbon-doped precursor glucose was added to the above precursor precipitate, and then calcined in an argon atmosphere at a temperature of 400° C. for 1 h. After cooling, a red co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst was obtained.

[0038] Embodiment three:

[0039] This embodiment provides a method for preparing a co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen, and the steps are as follows:

[0040] (1) Preparation of reaction product solution

[0041] 19.1 g TiCl4 (0.1 mol) and 7.5 g magnesium nitride (0.075 mol) were added to 200 ml toluene solution, and the mixture was subjected to solvent thermal reaction at 200° C. for 12 h in a reaction vessel to obtain a reaction product solution;

[0042] (2) Preparation of precursor precipitate

[0043] The above reaction product solution was added into 400 ml of 1 mol / L ammonium bicarbonate aqueous solution and stirred for hydrolysis reaction at pH 7-8 to make Ti 4+ Mg 2+ They were all transformed into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively, and after repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained;

[0044] (3) Calcination treatment of precursor precipitate

[0045] 0.3 g of carbon-doped precursor glucose was added to the above precursor precipitate, and then calcined in an argon atmosphere at a temperature of 350° C. for 2 h. After cooling, a red co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst was obtained.

[0046] The co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst prepared in the embodiment of the present invention is as follows: Figure 1 As shown, it has good crystallinity. 3- )∶n(Ti 4+ )<0.2, the crystal phase is pure anatase phase; when n(N 3- )∶n(Ti 4+ )>0.2, the main crystal phase is rutile phase; the amount of magnesium carbonate added is small and highly dispersed on the surface of titanium oxide particles, so that no diffraction peak is shown on XRD. Figure 2 As shown in the figure, the sample particles are 10 to 20 nm in size and are nearly spherical, and the particle lattice fringes are clearly visible. Figure 3 As shown in the figure, the samples show four elements, Ti, O, Mg, C, and N, in the micro-area, and the distribution is uniform. Figure 4 As shown in Figure 2, MgCO3 / CN-TiO2 strongly absorbs visible light. Figure 5 As shown, the (C, N) co-doped titanium oxide material has poor performance in photocatalytic water splitting and hydrogen evolution, while the use of MgCO3 / CN co-doping significantly improves the hydrogen evolution ability of the titanium oxide material.

Claims

1. A method for preparing a co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen, characterized in that The following steps are involved: (1) Preparation of reaction product solution According to the molar ratio n(N 3- )∶n(Ti 4+ )=0.1~1:1, adding TiCl4 and magnesium nitride into a toluene solution, and performing a solvent thermal reaction at 160~200° C. in a reaction kettle for 8~12 hours to obtain a reaction product solution; (2) Preparation of precursor precipitate According to the molar ratio n(NH4 + )∶n(Ti 4+ )=3~5:1, add the reaction product solution into an aqueous solution of ammonium bicarbonate with a concentration of 1 mol / L, and stir and hydrolyze at a pH value of 7~8 to make Ti 4+ Mg 2+ They were all transformed into N-Ti(OH)4 precipitate and MgCO3 precipitate respectively, and after washing, a yellow precursor precipitate was obtained; (3) Calcination treatment of precursor precipitate According to the molar ratio n(C6H 12 O6)∶n(Ti 4+ )=0.01~0.1:1, add carbon-doped precursor glucose to the precursor precipitate, and then calcine it in an argon atmosphere, the calcination temperature is 350~400℃, the insulation time is 1~2h, and after cooling, a red, co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst is obtained.

2. The product obtained by the method for preparing the co-doped titanium oxide photocatalyst for photolysis of water to produce hydrogen according to claim 1, characterized in that: The co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst is prepared according to the molar ratio n(N 3- )∶n(Ti 4+ )=0.1~1∶1、n(C 4+ )∶n(Ti 4+ )=0.06~0.12∶1.

3. The product according to claim 2, characterized in that: The nano-titanium oxide photocatalyst has a nearly spherical particle shape and a particle size of 10 to 20 nm.

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