A bismuth oxybromine-supported molybdenum oxide photocatalyst and its application in photocatalytic ammonia synthesis

Abstract

This invention discloses a bismuth oxybromine-supported molybdenum oxide photocatalyst and its application in photocatalytic ammonia synthesis. The catalyst is prepared according to the following steps: ammonium molybdate tetrahydrate is dispersed in distilled water and stirred at room temperature. Ethylene glycol is slowly added dropwise while stirring at room temperature. Then, bismuth oxybromine is added while stirring. The solution is hydrothermally reacted at 170-190℃ for 36-48 hours, cooled to room temperature, and the reaction solution is washed three times each with ethanol and deionized water, and dried at 50-60℃ to obtain the bismuth oxybromine-supported molybdenum oxide photocatalyst. The preparation method of the bismuth oxybromine-supported molybdenum oxide photocatalyst of this invention is simple. Compared with the pure BiOBr catalyst, the catalyst with MoO2 loading increases the number of active sites, and its ammonia synthesis activity is significantly improved. The activity of the loaded catalyst reaches 254.37 μmol·g. ‑1 ·h ‑1 .

Description

(I) Technical Field

[0001] This invention relates to a bismuth oxybromide-supported molybdenum oxide photocatalyst and its application in photocatalytic ammonia synthesis. (II) Background Technology

[0002] In recent years, research on semiconductor materials has become increasingly extensive. Layered bismuth oxyhalide (BiOX) possesses excellent visible-light photocatalytic activity due to its high chemical stability, low toxicity, low cost, and suitable intrinsic band gap, making it a potential photocatalyst widely used in CO2 reduction, N2 fixation, and water remediation. However, it still suffers from drawbacks such as low visible-light utilization and easy recombination of photogenerated electrons and holes, resulting in relatively low efficiency in photocatalytic nitrogen reduction. Therefore, methods such as constructing heterojunctions, doping, or creating vacancies are commonly used to modify it and improve its performance.

[0003] MoO2, as an inexpensive transition metal and a common metal oxide, is commonly used in lithium-ion batteries and electrochemical supercapacitors. Unlike other metal oxides, MoO2, with its twisted rutile structure, exhibits many unique properties, such as good chemical resistance, a high melting point, and excellent chemical stability, making it suitable as a catalyst or co-catalyst under visible light irradiation.

[0004] In existing technologies, bismuth oxyhalides have been applied to photocatalytic ammonia synthesis, but the results are still unsatisfactory. Bismuth oxyhalides suffer from weak visible light absorption, low electron-hole pair separation efficiency, and a limited number of active sites for adsorbing and activating nitrogen molecules. Furthermore, the poor hydrophilicity of the BiOBr surface limits its dispersion in water, ultimately inhibiting photocatalytic activity. Simultaneously, prolonged exposure to light causes photocorrosion, leading to poor catalyst stability and a short lifespan. (III) Summary of the Invention

[0005] The purpose of this invention is to provide a bismuth oxybromine supported molybdenum oxide photocatalyst and its application in photocatalytic ammonia synthesis. By coupling molybdenum oxide in the form of quantum dots onto layered bismuth oxyhalide, the light absorption range is effectively broadened and the semiconductor charge separation efficiency is improved. At the same time, the two form a heterojunction, and electron-hole migration pathways are formed, which is beneficial to the adsorption and reduction of N2, greatly improving the activity of photocatalytic ammonia synthesis. The bismuth oxybromine supported molybdenum oxide photocatalyst is prepared by hydrothermal method and applied as a photocatalyst for ammonia synthesis, which solves the problem of low photocatalytic ammonia synthesis activity of pure bismuth oxybromine and pure molybdenum oxide.

[0006] The technical solution adopted in this invention is:

[0007] This invention provides a bismuth oxybromine-supported molybdenum oxide photocatalyst, which is prepared according to the following steps: ammonium molybdate tetrahydrate is dispersed in distilled water and stirred at room temperature for 30-60 min (preferably 30 min); ethylene glycol is slowly added dropwise and stirred at room temperature for 30-60 min (preferably 30 min); then bismuth oxybromine is added under stirring and stirred for 10-20 min (preferably 10 min); the solution is hydrothermally reacted at 170-190 °C for 36-48 h, cooled to room temperature, and the reaction solution is washed three times with ethanol and deionized water, respectively, and dried at 50-60 °C to obtain the bismuth oxybromine-supported molybdenum oxide photocatalyst.

[0008] Furthermore, the molar ratio of molybdenum oxide to bismuth oxybromide in the bismuth oxybromide-supported molybdenum oxide photocatalyst is 1:1-5, preferably 1:5.

[0009] Furthermore, the volume of distilled water used is 50-500 mL / g based on the mass of ammonium molybdate tetrahydrate, preferably 270-280 mL / g; the volume of ethylene glycol used is 6-60 mL / g based on the mass of ammonium molybdate tetrahydrate, preferably 35-37 mL / g; and the mass ratio of bismuth oxybromide to ammonium molybdate tetrahydrate is 0.5-15:1, preferably 9-10:1.

[0010] Furthermore, the hydrothermal reaction was carried out in a Teflon stainless steel high-pressure reactor at 180 °C for 36 h.

[0011] Further, the bismuth oxybromide is prepared according to the following steps: Bi(NO3)3·5H2O (bismuth nitrate pentahydrate) is dissolved in 0.1M mannitol aqueous solution and stirred at room temperature for 10-30 min (preferably 10 min). Saturated sodium bromide aqueous solution is slowly added and stirred at room temperature for 10-30 min (preferably 10 min). Then, the mixture is hydrothermally reacted at 150-180 °C for 2-4 h. After cooling to room temperature, the reaction solution is washed three times with ethanol and distilled water, respectively, and dried at 50-60 °C for 3-5 h (preferably 60 °C for 4 h) to obtain bismuth oxybromide (BiOBr).

[0012] Furthermore, the saturated sodium bromide aqueous solution was slowly added at a rate of 4-6 mL / min. The hydrothermal reaction was carried out in a Teflon stainless steel high-pressure reactor at 160 °C for 3 h.

[0013] Furthermore, the volume of the mannitol aqueous solution used is 10-30 mL / mmol, preferably 25 mL / mmol, based on the amount of bismuth nitrate pentahydrate; the volume of the saturated sodium bromide aqueous solution used is 1-10 mL / mmol, preferably 5 mL / mmol, based on the amount of bismuth nitrate pentahydrate.

[0014] This invention also provides an application of bismuth oxybromide-supported molybdenum oxide photocatalyst in photocatalytic ammonia synthesis. The method of application is as follows: the bismuth oxybromide-supported molybdenum oxide photocatalyst is added to water, ultrasonically dispersed for 10 min, nitrogen gas is introduced, and the mixture is dark-treated for 30 min under magnetic stirring to achieve adsorption-desorption equilibrium between the catalyst and N2; then a simulated light source is turned on, and N2 generates ammonia gas under the action of light and catalyst, which dissolves in the water.

[0015] Furthermore, the water volume is 1-5 mL / g, preferably 4 mL / g, based on the mass of the bismuth oxybromine supported molybdenum oxide photocatalyst; the nitrogen gas introduction rate is 80-100 mL / min.

[0016] Furthermore, the simulated light source is a 300 W xenon lamp (200 nm < λ < 800 nm), with an irradiation distance of 15 cm and an irradiation time of 1 h.

[0017] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0018] A bismuth oxybromide-supported molybdenum oxide photocatalyst was prepared via a stepwise hydrothermal method, with molybdenum oxide highly dispersed on layered bismuth oxybromide to form a heterojunction. This improved the directional migration efficiency of photogenerated carriers and effectively enhanced the activity of free radical species. Furthermore, compared to the bismuth oxybromide catalyst, the anchored molybdenum oxide exhibited stronger hydrophilicity and could be effectively dispersed in the aqueous phase, which was beneficial for improving the adsorption of dissolved nitrogen molecules in the aqueous phase by the catalyst.

[0019] The bismuth oxybromine supported molybdenum oxide photocatalyst provided by this invention can be obtained through a simple preparation method. Compared with the pure BiOBr catalyst, the catalyst with MoO2 support increases the number of active sites, and its ammonia synthesis activity is significantly improved. The activity of the supported catalyst reaches 254.37 μmol·g. -1 ·h -1 Compared to pure MoO2 and BiOBr, its activity increased by approximately 4 times. (iv) Description of the attached drawings

[0020] Figure 1 The image shows the XRD pattern of BiOBr in Example 1.

[0021] Figure 2 The image shows the XRD pattern of MoO2 / BiOBr in Example 6.

[0022] Figure 3 This is a SEM image of BiOBr in Example 1.

[0023] Figure 4 This is a SEM image of MoO2 / BiOBr in Example 6.

[0024] Figure 5 NH4 in Example 8 + Standard curve; 'a' represents NH4 + The UV-Vis absorption spectrum of the standard curve; b represents the salicylic acid method for NH4 testing. + The standard curve. (V) Detailed Implementation Methods

[0025] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0026] The room temperature described in this invention is 25-30°C. The catalysts prepared in Examples 1-8 and Comparative Example 1 were structurally identified by XRD and SEM, respectively, to determine the corresponding products.

[0027] Example 1: Preparation of bismuth oxybromide

[0028] (1) Dissolve 1.46 g (3 mmol) of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 75 mL of 0.1 M mannitol aqueous solution and stir at room temperature for 10 min. This solution is denoted as solution A.

[0029] (2) Add 15 mL of saturated sodium bromide aqueous solution to solution A in step (1) slowly at a rate of 4 mL / min, stir at room temperature for 10 min, and obtain an approximately white suspension.

[0030] (3) Pour all of the suspension from step (2) into a 100 mL Teflon stainless steel high-pressure reactor and hydrothermally heat at 160 °C for 3 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and vacuum dry at 60 °C for 4 h to obtain bismuth oxybromide (BiOBr). The XRD pattern is shown in [Figure number missing]. Figure 1 SEM image (see) Figure 3 .

[0031] Example 2: Preparation of bismuth oxybromide-supported molybdenum oxide photocatalyst

[0032] (1) Disperse 1.16 g (0.94 mmol) ammonium molybdate tetrahydrate in 60 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0033] (2) Add 8 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0034] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide prepared by the method of Example 1 in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0035] (4) Pour all the solution from step (3) into a 150 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain a bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-0.5), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:0.5.

[0036] Example 3: Preparation of bismuth oxybromide-supported molybdenum oxide photocatalyst

[0037] (1) Disperse 0.58 g (0.47 mmol) ammonium molybdate tetrahydrate in 60 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0038] (2) Add 8 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0039] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide prepared by the method of Example 1 in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0040] (4) Pour all the solution from step (3) into a 150 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain a bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-1), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:1.

[0041] Example 4: Bismuth oxybromide-supported molybdenum oxide photocatalyst

[0042] (1) Disperse 0.19 g (0.16 mmol) ammonium molybdate tetrahydrate in 60 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0043] (2) Add 8 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0044] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide prepared by the method of Example 1 in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0045] (4) Pour all the solution from step (3) into a 150 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain a bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-3), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:3.

[0046] Example 5: Bismuth oxybromide-supported molybdenum oxide photocatalyst

[0047] (1) Disperse 0.15 g (0.12 mmol) ammonium molybdate tetrahydrate in 30 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0048] (2) Add 4 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0049] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide prepared by the method of Example 1 in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0050] (4) Pour all the solution from step (3) into a 150 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain a bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-4), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:4.

[0051] Example 6: Bismuth oxybromide-supported molybdenum oxide photocatalyst

[0052] (1) Disperse 0.11 g (0.09 mmol) ammonium molybdate tetrahydrate in 30 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0053] (2) Add 4 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0054] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0055] (4) Pour all the solution from step (3) into a 100 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and vacuum dry it at 60 °C for 4 h to obtain bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-5). The molar mass ratio of molybdenum oxide to bismuth oxybromine is 1:5. See the XRD pattern below. Figure 2 SEM image (see) Figure 4 .

[0056] Example 7: Bismuth oxybromide-supported molybdenum oxide photocatalyst

[0057] (1) Disperse 0.07 g (0.06 mmol) ammonium molybdate tetrahydrate in 30 mL of distilled water and stir at room temperature for 30 min. This solution is called solution A.

[0058] (2) Add 4 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0059] (3) Disperse 1 g (3.28 mmol) of bismuth oxybromide in the solution of step (2) with stirring and stir at room temperature for 10 min.

[0060] (4) Pour all the solution from step (3) into a 100 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain a bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr-8), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:8.

[0061] Comparative Example 1: Bismuth oxybromide-supported molybdenum oxide photocatalyst

[0062] (1) Disperse 0.11 g (0.09 mmol) ammonium molybdate tetrahydrate in 30 mL of distilled water and denote it as solution A.

[0063] (2) Disperse 0.15 g CTAB (hexadecyltrimethylammonium bromide) in 5 mL of ethanol and denote it as solution B.

[0064] (3) Then add all of solution B to all of solution A and stir at room temperature for 20 min.

[0065] (4) Adjust the pH of the solution to 1.5 with 1M HNO3, and record it as solution C. Stir at room temperature for 20 min.

[0066] (5) Disperse 1 g (3.28 mmol) of bismuth oxybromide in the entire solution in step (4) and stir at room temperature for 30 min.

[0067] (6) Pour all the solution from step (5) into a 100 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180°C for 48 h.

[0068] (7) After the reaction is complete, the reactor is cooled to room temperature.

[0069] (8) Wash with ethanol and distilled water three times each, and dry at 60 °C for 4 h to obtain bismuth oxybromine supported molybdenum oxide photocatalyst (MoO2 / BiOBr), with a molar mass ratio of molybdenum oxide to bismuth oxybromine of 1:5.

[0070] Comparative Example 2: Molybdenum oxide

[0071] (1) Disperse 2.47 g (2 mmol) ammonium molybdate tetrahydrate in 60 mL of distilled water and stir at room temperature for 30 min. This solution is denoted as solution A.

[0072] (2) Add 8 mL of ethylene glycol to solution A from step (1) and stir at room temperature for 30 min.

[0073] (3) Pour all the solution from step (2) into a 150 mL Teflon stainless steel high-pressure reactor and hydrothermally heat it at 180 °C for 36 h. After the reaction is complete, cool the reactor to room temperature. Wash the reaction solution three times with ethanol and distilled water, and dry it under vacuum at 60 °C for 4 h to obtain molybdenum oxide (MoO2) catalyst.

[0074] Comparative Example 3:

[0075] 1 g of bismuth oxybromine prepared by the method of Example 1 and 0.42 g of molybdenum oxide prepared by the method of Comparative Example 2 were mechanically ground and mixed to obtain a bismuth oxybromine and molybdenum oxide photocatalyst (MoO2 / BiOBr-mechanical mixture).

[0076] Example 8: Photocatalysis Experiment

[0077] 1. Ammonia synthesis via simulated solar photocatalysis was used as a model reaction. The absorbance at 655 nm was measured using a UV-Vis spectrophotometer, and the amount of ammonia produced was determined by combining the absorbance with an ammonia standard curve to evaluate the photocatalytic performance of the material. In the experiment, a 300 W xenon lamp (200 nm < λ < 800 nm) was used as a simulated visible light source, with an irradiation distance of 15 cm.

[0078] 10 mg of catalyst was added to 40 mL of water and sonicated for 10 min to ensure uniform dispersion. The solution was then transferred to a double-layered reaction tube. N2 was then introduced at a rate of 80 mL / min, and the mixture was treated in the dark with magnetic stirring for 30 min to achieve adsorption-desorption equilibrium between the catalyst and N2. A simulated light source was then turned on, and N2, under the influence of light and the catalyst, generated ammonia gas which dissolved in the water. After 1 h of reaction, 2 mL of the solution was taken from the quartz tube, filtered through a 0.22 μm organic filter membrane, and 2 mL of reagent A, 1 mL of reagent B, and 0.2 mL of reagent C were added. After 2 h, the absorbance at 655 nm was measured. The ammonia concentration C (μmol / g / h) was calculated based on the ammonia standard curve.

[0079] The catalysts from the above examples and comparative examples were subjected to photocatalytic ammonia synthesis experiments under the aforementioned conditions, and the final activities are shown in Table 1. Table 1 shows that a molar ratio of molybdenum oxide to bismuth oxybromide of 1:1-5 provides a suitable amount of MoO2 composite in the catalyst, which improves the photocatalytic ammonia synthesis activity. The highest activity of 254.37 μmol / g / h is achieved when the molar ratio of molybdenum oxide to bismuth oxybromide is 1:5. Although Comparative Example 1 showed a high ammonia production concentration, it suffered from changes in the morphology of bismuth oxybromide. Comparative Example 2, using molybdenum oxide alone, and Comparative Example 3, using a mechanical mixture of molybdenum oxide and bismuth oxybromide as photocatalysts, both resulted in relatively low ammonia production concentrations.

[0080] Table 1 Ammonia production concentrations of different catalysts

[0081]

[0082] 2. Preparation of ammonia standard curve

[0083] (1) Weigh 1.0 g of NH4Cl and dry it in a forced-air drying oven at 105 °C for 2 h.

[0084] (2) Take the dried NH4Cl and prepare a 4 μg / mL ammonia standard solution with distilled water.

[0085] (3) Using a 1000 μL pipette, take 0, 50, 100, 150, 200, 250, 400, 750, 1250 and 2000 μL of NH4 respectively. + Add the standard solution to 5 mL colorimetric tubes, and then dilute with distilled water to 2 mL.

[0086] (4) Finally, add 2 mL of reagent A, 1 mL of reagent B, and 0.2 mL of reagent C to the above series of solutions respectively, shake well, and let stand for 2 h. Scan the UV-Vis spectrophotometer in the range of 200-800 nm. The UV-Vis absorption spectra are shown in the figure. Figure 5As shown in Figure a, a linear fit was then performed at λ=655 nm to obtain NH4. + The standard curve of absorbance A versus concentration C is shown below. Figure 5 As shown in b.

Claims

1. A bismuth oxybromide-supported molybdenum oxide photocatalyst, characterized in that, The catalyst is prepared according to the following steps: Ammonium molybdate tetrahydrate is dispersed in distilled water and stirred at room temperature for 30-60 min. Ethylene glycol is slowly added dropwise and stirred at room temperature for 30-60 min. Then, bismuth oxybromine is added under stirring and stirred for 10-20 min. The solution is hydrothermally reacted at 170-190 °C for 36-48 h, cooled to room temperature, and the reaction solution is washed three times with ethanol and deionized water, respectively, and dried at 50-60 °C to obtain bismuth oxybromine-supported molybdenum oxide photocatalyst. The molar ratio of molybdenum oxide to bismuth oxybromine in the bismuth oxybromine-supported molybdenum oxide photocatalyst is 1:1-5. The bismuth oxybromine is prepared according to the following steps: Bismuth nitrate pentahydrate is dissolved in 0.1 M mannitol aqueous solution and stirred at room temperature for 10-30 min. Saturated sodium bromide aqueous solution is slowly added and stirred at room temperature for 10-30 min. The solution is then hydrothermally reacted at 150-180 °C for 2-4 h, cooled to room temperature, and the reaction solution is washed three times with ethanol and deionized water, respectively, and dried at 50-60 °C. The bismuth oxybromide was obtained by drying at ℃ for 3-5 h.

2. The bismuth oxybromide-supported molybdenum oxide photocatalyst as described in claim 1, characterized in that, In the catalyst preparation step, the volume of distilled water used is 20-100 mL / g based on the mass of ammonium molybdate tetrahydrate; the volume of ethylene glycol used is 3-15 mL / g based on the mass of ammonium molybdate tetrahydrate; and the mass ratio of bismuth oxybromide to ammonium molybdate tetrahydrate is 0.5-2.5:

1.

3. The bismuth oxybromide-supported molybdenum oxide photocatalyst as described in claim 1, characterized in that, In the catalyst preparation step, the hydrothermal reaction is carried out in a Teflon stainless steel high-pressure reactor at 180 °C for 36 h.

4. The bismuth oxybromide-supported molybdenum oxide photocatalyst as described in claim 1, characterized in that, In the bismuth oxybromide preparation step, the saturated sodium bromide aqueous solution is slowly added at a rate of 4-6 mL / min; the hydrothermal reaction is carried out in a Teflon stainless steel high-pressure reactor at 160 °C for 3 h.

5. The bismuth oxybromide-supported molybdenum oxide photocatalyst as described in claim 1, characterized in that, The volume of the mannitol aqueous solution used is 10-30 mL / mmol based on the amount of bismuth nitrate pentahydrate; the volume of the saturated sodium bromide aqueous solution used is 1-10 mL / mmol based on the amount of bismuth nitrate pentahydrate.

6. The application of the bismuth oxybromide-supported molybdenum oxide photocatalyst of claim 1 in the photocatalytic synthesis of ammonia.

7. The application as described in claim 6, characterized in that, The method of application is as follows: bismuth oxybromide supported molybdenum oxide photocatalyst is added to water, ultrasonically dispersed for 10 min, nitrogen gas is introduced, and the mixture is dark-treated for 30 min under magnetic stirring to achieve adsorption-desorption equilibrium between the catalyst and N2; then a simulated light source is turned on, and N2 generates ammonia gas under the action of light and catalyst, and dissolves in the water.

8. The application as described in claim 7, characterized in that, The water volume used is 1-5 mL / g based on the mass of the bismuth oxybromine supported molybdenum oxide photocatalyst; the nitrogen gas introduction rate is 80-100 mL / min; the simulated light source is a 300 W xenon lamp with an irradiation distance of 15 cm.

Images