A method for preparing a co-doped titanium dioxide photocatalyst for hydrogen production by water splitting and the product thereof.

Abstract

This invention discloses a method for preparing a co-doped titanium dioxide photocatalyst for water splitting to produce hydrogen, and the product obtained therefrom. The method uses TiCl4 and magnesium nitride as raw materials, and adjusts the nitrogen content... 3‑ / Ti 4+ By adjusting the molar ratio and adding carbon doping, a co-doped MgCO3 / C-N-TiO2 nano-titanium oxide photocatalyst was formed, which effectively improved the photocatalytic hydrogen production performance of TiO2. Under irradiation with a 300W xenon lamp, the hydrogen evolution performance reached 2-3 mmol / gh. This provides a new approach for the preparation of co-doped anatase titanium oxide photocatalysts and can well meet the industrial demand for photocatalytic hydrogen production from titanium oxide materials.

Description

Technical Field

[0001] This invention relates to the field of nano-photocatalyst materials technology, and in particular to a method for preparing a doped titanium dioxide photocatalyst for hydrogen production by photocatalysis of water and the product obtained therefrom. Background Technology

[0002] Titanium dioxide (TiO2) is an important new energy and environmental protection material with applications in photocatalysis, solar power generation, and environmental protection. However, the wide bandgap of TiO2 materials suffers from problems such as a narrow light absorption range and low electron-hole pair separation efficiency, severely limiting its practical applications. Research results indicate that doping TiO2 with non-metallic ions, such as H, C, and N, can effectively narrow its bandgap. In particular, when H is incorporated into titanium oxide at a certain concentration, it turns the titanium oxide black, increasing its visible light absorption rate to over 80%. However, this H-doped titanium oxide suffers from poor chemical stability and easy oxidation, making it difficult to meet the requirements of efficient solar hydrogen production.

[0003] Currently, existing methods for preparing nitrogen-doped titanium dioxide mainly involve high-temperature ammonia diffusion and high-temperature nitrogen precursor diffusion. For example, ammonia or dimethyl imidazole can be used as the nitrogen source to achieve nitrogen doping at high temperatures. However, this high-temperature diffusion method easily produces interstitial nitrogen doping, which is very detrimental to the photocatalytic performance of titanium dioxide (the higher the nitrogen doping level, the worse the photocatalytic water splitting and hydrogen evolution performance). How to achieve highly doped, substituted nitrogen-doped titanium dioxide materials and improve their photocatalytic water splitting and hydrogen evolution performance has always been a challenge in the field of photochemistry. Research results show that (C,N) co-doping can improve the photocatalytic oxidation performance of titanium dioxide materials, but it does not significantly improve its photocatalytic reduction performance. Therefore, existing technologies still cannot meet the industrial requirements for photocatalytic hydrogen production using titanium dioxide materials. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a co-doped titanium dioxide photocatalyst for water splitting to produce hydrogen, thereby obtaining a highly doped, substituted N-doped titanium dioxide photocatalyst, effectively improving the photocatalytic hydrogen production performance of TiO2, and providing a new approach for the preparation of co-doped anatase titanium dioxide photocatalysts to meet the industrial demand for photocatalytic hydrogen production using titanium dioxide materials. Another objective of this invention is to provide a product obtained using the above-described preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The present invention provides a method for preparing a co-doped titanium dioxide photocatalyst for photocatalytic water splitting 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+ The ratio of TiCl4 to magnesium nitride (Mg3N2) is 0.1 to 1:1. TiCl4 and magnesium nitride (Mg3N2) are added to toluene solution and reacted in a reaction vessel at 160 to 200 °C for 8 to 12 hours to obtain the reaction product solution.

[0009] (2) Preparation of precursor precipitate

[0010] According to the molar ratio n(NH4) + )∶n(Ti 4+ The product solution was added to a 1 mol / L ammonium bicarbonate aqueous solution at a ratio of 3 to 5:1, and the reaction was carried out under stirring hydrolysis at a pH of 7 to 8, so that Ti... 4+ Mg 2+ All of them were converted into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively. After washing, a yellow precursor precipitate was obtained.

[0011] (3) Calcination treatment of precursor precipitates

[0012] According to the molar ratio n(C6H) 12 O6)∶n(Ti 4+ The ratio of 0.01 to 0.1:1 is used to add carbon-doped glucose precursor to the precursor precipitate, and then calcination is carried out under an argon atmosphere at a temperature of 350 to 400°C for 1 to 2 hours. After cooling, a red, co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst is obtained.

[0013] The product prepared using the above-described method for preparing co-doped titanium dioxide photocatalyst for water splitting to produce hydrogen, wherein the co-doped MgCO3 / CN-TiO2 nano-titanium dioxide photocatalyst is prepared according to a molar ratio n(N) 3- )∶n(Ti 4+ )=0.1~1∶1、n(C 4+ )∶n(Ti 4+ The ratio is 0.06 to 0.12:1. The morphology of the nano-titanium oxide photocatalyst is a near-spherical particle with a particle size of 10 to 20 nm.

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

[0015] This invention employs a solvothermal-assisted heat treatment method to prepare co-doped nano-titanium oxide photocatalysts, by adjusting N... 3- / Ti 4+The molar ratio of high doping content and substituted N-doped nano-titanium oxide powder is used to form MgCO3 / CN-TiO2 powder. The resulting MgCO3 / CN-TiO2 powder is red and has an anatase phase, which can effectively improve the photocatalytic hydrogen production performance of TiO2. Under irradiation with a 300W xenon lamp, the hydrogen evolution performance reaches 2-3 mmol / gh. Attached Figure Description

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

[0017] Figure 1 These are X-ray crystal diffraction patterns of the co-doped titanium dioxide photocatalysts prepared in the embodiments of the present invention (sample1 is Example 1, sample2 is Example 2, and sample3 is Example 3);

[0018] Figure 2 These are transmission electron microscope (TEM) images of the co-doped titanium dioxide photocatalysts prepared in the embodiments of the present invention (sample 1 is Example 1, sample 2 is Example 2, and sample 3 is Example 3).

[0019] Figure 3 This is a transmission electron microscope (TEM) microarray of the co-doped titanium dioxide photocatalyst prepared in Example 1 of this invention.

[0020] Figure 4 This is a comparison of the UV-Vis absorption spectra of the co-doped titanium dioxide photocatalyst prepared in the embodiments of the present invention and commercial P25 powder (sample1 is Example 1, sample2 is Example 2, and sample3 is Example 3);

[0021] Figure 5 The photocatalytic hydrogen evolution performance of the co-doped titanium oxide photocatalyst prepared in the embodiments of the present invention is shown in the following examples (sample1 is Example 1, sample2 is Example 2, and sample3 is Example 3). Detailed Implementation

[0022] Example 1:

[0023] This embodiment describes a method for preparing a co-doped titanium dioxide photocatalyst for photocatalytic water splitting to produce hydrogen, the steps of which 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 reacted in a reaction vessel at 200 °C for 12 h to obtain the reaction product solution.

[0026] (2) Preparation of precursor precipitate

[0027] The above reaction product solution was added to 400 ml of a 1 mol / L ammonium bicarbonate aqueous solution, and a stirring hydrolysis reaction was carried out under conditions of pH 7-8 to allow Ti to undergo further hydrolysis. 4+ Mg 2+ All of them were converted into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively. After repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained.

[0028] (3) Calcination treatment of precursor precipitates

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

[0030] Example 2:

[0031] This embodiment describes a method for preparing a co-doped titanium dioxide photocatalyst for photocatalytic water splitting to produce hydrogen, the steps of which 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 reacted in a reaction vessel at 200 °C for 12 h to obtain the reaction product solution.

[0034] (2) Preparation of precursor precipitate

[0035] The above reaction product solution was added to 400 ml of a 1 mol / L ammonium bicarbonate aqueous solution, and a stirring hydrolysis reaction was carried out under conditions of pH 7-8 to allow Ti to undergo further hydrolysis. 4+ Mg 2+ All of them were converted into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively. After repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained.

[0036] (3) Calcination treatment of precursor precipitates

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

[0038] Example 3:

[0039] This embodiment describes a method for preparing a co-doped titanium dioxide photocatalyst for photocatalytic water splitting to produce hydrogen, the steps of which 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 reacted in a reaction vessel at 200 °C for 12 h to obtain the reaction product solution.

[0042] (2) Preparation of precursor precipitate

[0043] The above reaction product solution was added to 400 ml of a 1 mol / L ammonium bicarbonate aqueous solution, and a stirring hydrolysis reaction was carried out under conditions of pH 7-8 to allow Ti to undergo further hydrolysis. 4+ Mg 2+ All of them were converted into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively. After repeated washing with deionized water and anhydrous ethanol, a yellow precursor precipitate was obtained.

[0044] (3) Calcination treatment of precursor precipitates

[0045] 0.3g of carbon-doped glucose precursor was added to the above precursor precipitate, and then calcined under an argon atmosphere at a temperature of 350℃ for 2 hours. 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 embodiments of the present invention, such as Figure 1 As shown, it has good crystallinity, when n(N) 3- )∶n(Ti 4+ When n(N) < 0.2, the crystal phase is pure anatase; when n(N) < 0.2, the crystal phase is pure anatase. 3- )∶n(Ti 4+ When the concentration of magnesium carbonate (Mg) is greater than 0.2, the main crystalline phase is rutile; the amount of magnesium carbonate added is small and highly dispersed on the surface of the titanium dioxide particles, so that no diffraction peaks are shown on the XRD. Figure 2 As shown, the sample particles are nearly spherical in shape, ranging from 10 to 20 nm, and the particle lattice fringes are clearly visible. Figure 3 As shown, the sample exhibits the four elements Ti, O, Mg, C, and N in the micro-region, and their distribution is uniform. Figure 4 As shown, MgCO3 / CN-TiO2 exhibits strong absorption of visible light. For example... Figure 5 As shown, the hydrogen evolution performance of (C, N) co-doped titanium oxide materials is very poor. However, the hydrogen evolution ability of titanium oxide materials is significantly improved after co-doping with MgCO3 / CN.

Claims

1. A method for preparing a co-doped titanium dioxide photocatalyst for photocatalytic water splitting to produce hydrogen, characterized in that... The following steps are involved: (1) Preparation of reaction product solution According to molar ratio n (N 3- )∶ n (Ti 4+ The ratio of TiCl4 to magnesium nitride is 0.1 to 1:

1. TiCl4 and magnesium nitride are added to toluene solution and reacted in a reaction vessel at 160 to 200 °C for 8 to 12 hours to obtain the reaction product solution. (2) Preparation of precursor precipitate According to molar ratio n (NH4 + )∶ n (Ti 4+ The product solution was added to a 1 mol / L ammonium bicarbonate aqueous solution at a ratio of 3 to 5:1, and the reaction was carried out under stirring hydrolysis at a pH of 7 to 8, so that Ti... 4+ Mg 2+ All of them were converted into N-Ti(OH)4 precipitate and MgCO3 precipitate, respectively. After washing, a yellow precursor precipitate was obtained. (3) Calcination treatment of precursor precipitates According to molar ratio n (C6H 12 O6)∶ n (Ti 4+ The ratio of 0.01 to 0.1:1 is used to add carbon-doped glucose precursor to the precursor precipitate, and then calcination is carried out under an argon atmosphere at a temperature of 350 to 400°C for 1 to 2 hours. After cooling, a red, co-doped MgCO3 / CN-TiO2 nano-titanium oxide photocatalyst is obtained.

2. The product obtained by the preparation method of the co-doped titanium dioxide photocatalyst for hydrogen production by water splitting as described in claim 1.

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

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