阅读说明：本技术 一种BiOCl/MoO2复合催化剂及其制备方法和应用 (BiOCl/MoO2Composite catalyst and preparation method and application thereof ) 是由 王文中 肖彩林 张玲 周璟 于 2019-09-23 设计创作，主要内容包括：本发明涉及一种BiOCl/MoO-2复合催化剂及其制备方法和应用,所述BiOCl/MoO-2复合催化剂包括：BiOCl基体材料、以及在所述BiOCl基体材料表面上负载的MoO-2纳米片。(The invention relates to BiOCl/MoO 2 Composite catalyst, preparation method and application thereof, and BiOCl/MoO 2 The composite catalyst comprises: BiOCl base material and MoO loaded on surface of BiOCl base material 2 Nanosheets.)

1. BiOCl/MoO₂The composite catalyst is characterized in that the BiOCl/MoO₂The composite catalyst comprises: BiOCl base material and table of BiOCl base materialMoO loaded on surface₂Nanosheets.

2. BiOCl/MoO according to claim 1₂The composite catalyst is characterized in that the BiOCl base material is a BiOCl nano sheet, the size of the BiOCl nano sheet is 0.1-1 mu m, and the thickness of the BiOCl nano sheet is 10-100 nm.

3. BiOCl/MoO according to claim 1 or 2₂Composite catalyst, characterized in that the MoO₂The content of the nano-sheets is 5-90 wt%, preferably 10-60 wt%, and more preferably 50 wt%.

4. BiOCl/MoO according to any of claims 1 to 3₂Composite catalyst, characterized in that the MoO₂The size of the nano sheet is 10-50 nm, and the thickness of the nano sheet is 1-10 nm.

5. A BiOCl/MoO according to any one of claims 1 to 4₂The preparation method of the composite catalyst is characterized in that the BiOCl matrix material and MoO are mixed₂Placing the nanosheets into a mortar, and grinding for 0.1-0.5 hours to obtain the BiOCl/MoO₂And (3) compounding a catalyst.

6. The method according to claim 1, wherein the BiOCl matrix material is prepared by a method comprising:

(1) mannitol and deionized water were mixed and Bi (NO) was added₃)₃Then, dropwise adding a saturated KCl aqueous solution to obtain a mixed solution;

(2) and carrying out hydrothermal treatment on the obtained mixed solution at 100-200 ℃ for 4-24 hours, and then washing and drying to obtain the BiOCl base material.

7. The method according to claim 1, wherein the mannitol is contained in a volume of 5 to 50 ml; the Bi (NO)₃)₃The mass of (A) is 0.5-15 g; the volume of the saturated KCl aqueous solution is 5-50 ml.

8. The method of claim 1, wherein the MoO is present in a liquid₂The preparation method of the nano-sheet comprises the following steps:

(1) adding MoCl₅Dissolving in ethanol, and adding deionized water and a proper amount of nitric acid to obtain a mixed solution:

(2) carrying out hydrothermal treatment on the obtained mixed solution at the temperature of 150-200 ℃ for 12-24 hours, and then washing and drying to obtain the MoO₂Nanosheets.

9. The method of claim 8, wherein the MoCl is present₅The mass of (A) is 0.5-15 g; the concentration of the nitric acid is 10-60 wt%, and the volume of the nitric acid is 0.1-10 ml.

10. A BiOCl/MoO according to any of claims 1 to 4₂The application of the composite catalyst in the field of photocatalysis nitrogen fixation is characterized in that BiOCl/MoO₂Mixing the composite catalyst and water according to a molar ratio of 100: 1-1: 10000, and adding N in the air₂As reactant, N is irradiated under light source₂The adsorption activation of (3); the light source is sunlight or 100-500W xenon lamp light.

Technical Field

The invention relates to BiOCl/MoO₂A composite catalyst, a preparation method and an application thereof, in particular to a BiOCl/MoO-based catalyst₂A composite material, a preparation method thereof and application thereof in the field of nitrogen fixation.

Background

N₂As a raw material for ammonia synthesis, N is abundant in earth₂The molecule is nonpolar, the nitrogen-nitrogen triple bond has 945kJ/mol bond energy, and the first bond dissociation energy is high, the nucleophilicity to proton is weak, and the molecule is extremely difficult to be absorbedAnd (4) reducing. At present, the artificial nitrogen fixation is mainly carried out by a haber method, the reaction conditions are harsh, the artificial nitrogen fixation needs to be carried out at high temperature and high pressure, the energy consumption is high, and simultaneously, a large amount of CO is accompanied₂And (5) discharging. Therefore, from the viewpoint of cost control and environmental protection, it is of great significance to study artificial nitrogen fixation under mild conditions. In recent years, scientists find that the solar energy is used as a driving force in the nitrogen fixation reaction process to replace the harsh conditions of high temperature and high pressure in the haber method, but the efficiency of the catalytic reaction is far lower than the expectation of people. Therefore, the development of a photocatalytic nitrogen fixation material with high efficiency, environmental protection and mild technical conditions is attracting more and more attention.

The existing photocatalysis nitrogen fixation technology has a plurality of difficulties: 1) catalyst pair N due to limited surface defects₂The adsorption activation amount of (A) is insufficient; 2) the photon-generated carriers are easy to recombine; 3) the oxidation capability to water is weak and protons required for the nitrogen fixation reaction cannot be provided. BiOCl is a two-dimensional layered semiconductor material, has strong water oxidation capacity and is widely applied to the field of photocatalysis. However, the photon-generated carriers of BiOCl are easy to recombine, the utilization rate of light is low, and limited surface defects and N are generated₂The adsorption activation capability of the BiOCl is poor, and researchers improve the utilization rate of photon-generated carriers of the BiOCl, the absorption of the BiOCl to light and N through various means (such as constructing a semiconductor heterojunction, loading noble metal, doping metal or nonmetal, adding a sacrificial agent and the like)₂Adsorption activation ability of (1). However, the modified BiOCl system catalyst material still needs to realize photocatalytic nitrogen fixation at high temperature and high pressure, and a large amount of CO exists₂The emission and the energy consumption are large, and the like.

Disclosure of Invention

Aiming at the high temperature, high pressure and large amount of CO existing in the commonly adopted Haber method ammonia synthesis technology₂The invention aims to provide BiOCl/MoO₂Composite catalyst (or BiOCl/MoO)₂Composite material), a preparation method thereof and application of photocatalysis nitrogen fixation, finally realizing higher nitrogen fixation efficiency in pure water, belonging to a mild and environment-friendly catalysis method.

On the one hand, the method comprises the following steps of,the invention provides BiOCl/MoO₂Composite catalyst, said BiOCl/MoO₂The composite catalyst comprises: BiOCl base material and MoO loaded on surface of BiOCl base material₂Nanosheets.

In this disclosure, BiOCl/MoO₂Positively charged BiOCl matrix material and negatively charged MoO in composite catalyst₂The nano-sheets are combined through electrostatic adsorption, and the BiOCl matrix material has good light absorption capacity and MoO₂The introduction of the BiOCl is beneficial to accelerating the migration rate of the carriers on the surface of the BiOCl base material, realizing higher carrier separation efficiency and being capable of being N₂Provides reactive sites for further enhancing the activity of N₂So that efficient nitrogen fixation efficiency can be achieved.

Preferably, the BiOCl base material is a BiOCl nano sheet, the size of the BiOCl nano sheet is 0.1-1 mu m, and the thickness of the BiOCl nano sheet is 10-100 nm.

Preferably, the MoO₂The content of the nano-sheets is 5-90 wt%, preferably 10-60 wt%, and more preferably 50 wt%.

Preferably, the MoO₂The size of the nano sheet is 10-50 nm, and the thickness of the nano sheet is 1-10 nm.

In another aspect, the present invention provides a BiOCl/MoO as described above₂The preparation method of the composite catalyst comprises the steps of mixing BiOCl base material and MoO₂Placing the nanosheets into a mortar, and grinding for 0.1-0.5 hours to obtain the BiOCl/MoO₂And (3) compounding a catalyst. Grinding treatment to make BiOCl matrix material and MoO₂And mixing the nano sheets uniformly.

Preferably, the preparation method of the BiOCl matrix material comprises the following steps:

(1) dissolving mannitol in deionized water, mixing, and adding Bi (NO)₃)₃Then, dropwise adding a saturated KCl aqueous solution to obtain a mixed solution;

(2) and carrying out hydrothermal treatment on the obtained mixed solution at 100-200 ℃ for 4-24 hours, and then washing and drying to obtain the BiOCl base material.

In addition, the volume of the mannitol is preferably 5-50 ml; what is needed isThe above Bi (NO)₃)₃The mass of (A) is 0.5-15 g; the volume of the saturated KCl aqueous solution is 5-50 ml.

Preferably, the MoO₂The preparation method of the nano-sheet comprises the following steps:

(1) adding MoCl₅Dissolving in ethanol, and adding deionized water and a certain amount of concentrated nitric acid to obtain a mixed solution:

(2) carrying out hydrothermal treatment on the obtained mixed solution at the temperature of 150-200 ℃ for 12-24 hours, and then washing and drying to obtain the MoO₂Nanosheets.

Also, preferably, the MoCl₅The mass of (A) is 0.5-15 g; the concentration of the nitric acid is 10-60 wt%, and the volume of the nitric acid is 0.1-10 ml.

In another aspect, the invention provides a BiOCl/MoO as described above₂The application of the composite catalyst in the field of photocatalysis nitrogen fixation is to mix BiOCl/MoO₂Ultrasonically dispersing the composite catalyst and water according to the molar ratio of 100: 1-1: 10000, and adding N in the air₂As reactant, N is irradiated under light source₂The adsorption activation of (3); the light source is sunlight or 100-500W xenon lamp light.

In the invention, the BiOCl/MoO₂In the process of the photocatalytic nitrogen fixation reaction, the composite catalyst only uses water as a proton source, and does not need to introduce an organic solvent which is toxic to the environment, thereby greatly reducing the pollution to the environment and improving the environmental friendliness of the reaction. The BiOCl matrix material can oxidize pure water well, provide more protons for nitrogen fixation reaction, and does not use any chemical reagent which is toxic and harmful to the environment; MoO₂The nano sheet is compounded with BiOCl matrix material, and the interface of the nano sheet can be used as N₂Adsorption of activated sites, increase of p-N₂The adsorption and activation are carried out, and the nitrogen fixation efficiency is further improved.

Preferably, the mixing is performed by stirring in a dark and open system for at least 0.5 hour (e.g., 0.5 to 8 hours) to reach N₂The adsorption and desorption are balanced.

Compared with the prior art, the invention has the following beneficial effects:

(1) in the present invention, BiOCl/MoO₂Composite photocatalytic material (BiOCl/MoO)₂Composite catalyst) for reducing N only by electrons generated from the material itself₂The method has the advantages that the protons are obtained by removing the oxidized water through the holes, the feasibility is good, and the photocatalysis nitrogen fixation activity is high. The material has the ammonia nitrogen yield of 35 mu mol/g in pure water under the simulated solar illumination, and is the higher efficiency of photocatalysis nitrogen fixation in pure water under the solar energy condition reported at home and abroad at present. Under the same conditions, materials such as Fe-Al co-loaded 3D graphene can only generate 25.3 mu mol/g ammonia nitrogen. Therefore, the composite material obtained by the invention shows the advantage of high-efficiency nitrogen fixation under natural conditions (normal temperature and normal pressure process, no heating and pressurization), and has better application prospect;

(2) in the present invention, BiOCl/MoO₂The preparation method of the composite photocatalytic material does not need special equipment and harsh conditions, has simple process and strong controllability, is easy to realize large-scale production and has practicability.

Drawings

FIG. 1 shows the synthesis of BiOCl/MoO according to the invention₂XRD pattern (a) and SEM pattern (B) of the composite catalyst;

FIG. 2 shows BiOCl/MoO of different ratios in example 1 of the present invention₂A nitrogen fixation efficiency schematic diagram of the composite catalyst;

FIG. 3 shows BiOCl/MoO in example 2 of the present invention₂A nitrogen fixation cycle performance schematic diagram of the catalyst (mass ratio 1: 1);

FIG. 4 shows MoO in comparative example 1 of the present invention₂Loaded BiOCl/MoO₂Composite catalyst and free of MoO₂Nitrogen fixation performance of the supported BiOCl catalyst is shown schematically.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, BiOCl is used as a matrix material, and MoO is loaded on the surface of the BiOCl₂Nanosheet, and BiOCl/MoO is prepared₂The composite material realizes a higher photocatalytic nitrogen fixation technology in water without any additive. The method is simple and feasible, clean and efficient, does not need any additive, and is energy-saving and environment-friendly。

In alternative embodiments, the BiOCl matrix material can be BiOCl nanoplates. The size of the BiOCl nano sheet can be 0.1-1 mu m, and the thickness can be 10-100 nm. MoO₂The size of the nano-sheet can be 10-50 nm, and the thickness can be 1-10 nm.

In an alternative embodiment, the MoO₂The content of the nano-sheets is 5-90 wt%, preferably 10-60 wt%, and more preferably 50 wt%.

The following is an exemplary illustration of BiOCl/MoO provided by the present invention₂A method for preparing a composite material.

And (3) preparing BiOCl nano sheets. Dissolving a certain amount of mannitol in deionized water, stirring uniformly, and then adding a certain amount of Bi (NO)₃)₃Stirring evenly, and finally dripping saturated KCl solution. And transferring the obtained mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 100-200 ℃ for 4-24 hours, cooling, washing and drying to obtain the BiOCl nanosheet. Wherein the volume of mannitol is 5-50 ml. Bi (NO)₃)₃The mass of (b) may be 0.5 to 15 g. The volume of the saturated KCl aqueous solution can be 5-50 ml. It is to be understood that the preparation method of the BiOCl nanosheets of the present invention includes, but is not limited to, hydrothermal methods and the like.

MoO₂And (3) preparing the nano sheet. Adding a certain amount of MoCl₅Dissolving in an ethanol solution, adding a certain amount of deionized water and a nitric acid solution, stirring and mixing uniformly, transferring into a hydrothermal reaction kettle, carrying out hydrothermal treatment at 150-200 ℃ for 12-24 hours, cooling, washing and drying to obtain MoO₂Nanosheets. Wherein, MoCl₅The mass of (b) may be 0.5 to 15 g. The concentration of the nitric acid can be 10-60 wt%, and the volume can be 0.1-10 ml.

Mixing BiOCl nanosheets and MoO₂The nano sheets are weighed according to the mass ratio, ground at room temperature for 0.1-0.5 hours and uniformly mixed to obtain BiOCl/MoO₂Composite material (BiOCl/MoO)₂A composite catalyst).

As a BiOCl/MoO₂A detailed example of the preparation method of the composite catalyst includes the steps of:

1) dissolving mannitol in deionized water, stirring, and addingAdding a certain amount of Bi (NO)₃)₃Uniformly stirring, and finally dropwise adding a saturated KCl solution, and stirring for 0.5h to obtain a mixed solution;

2) transferring the mixed solution obtained in the step 1) into a hydrothermal kettle, carrying out hydrothermal reaction for 4 hours at 160 ℃, and then cooling, washing and drying to obtain a BiOCl nano sheet with a moderate size;

3) adding a certain amount of MoCl₅Dissolving in ethanol solution, adding a certain amount of deionized water and nitric acid, mixing well, transferring to a hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 12h, cooling, washing and drying to obtain MoO₂Nanosheets;

4) weighing a certain amount of BiOCl and MoO obtained in the steps 2) and 3)₂Placing the nanosheets into a mortar, grinding for 0.5h to uniformly mix the nanosheets to obtain BiOCl/MoO₂A composite material. The BiOCl/MoO obtained₂The composite material is nano powder composed of two-dimensional layered materials.

In one embodiment of the present invention, BiOCl/MoO₂Composite material (BiOCl/MoO)₂Composite catalyst) is used for obtaining ammonia through photocatalysis in an aqueous solution reaction system, and N in the air is used under the condition of no addition of any sacrificial agent under the illumination of a xenon lamp₂As a nitrogen source, a high nitrogen fixation efficiency (35. mu. mol/g/h)) was achieved in pure water. Protons required by the photocatalytic reaction are only from water, and no other oxidant or auxiliary agent is needed to be added, and no noble metal is needed to be used; reduces energy consumption and environmental pollution.

Adding BiOCl/MoO₂Mixing the composite catalyst with water, and stirring for about 0.5h in a dark place to obtain N₂The adsorption and desorption are balanced. Wherein, BiOCl/MoO₂The molar ratio of the composite catalyst to water can be 100: 1-1: 10000. For example, 0.01 to 5g of BiOCl/MoO₂The composite material is mixed with 10-100 mL of water, and then stirred in the dark for a certain time to reach absorption and desorption equilibrium, for example, 0.5-8 hours. In the invention, the photocatalytic nitrogen fixation process is carried out in an open system. As an example, BiOCl/MoO may be used₂After mixing the composite material catalyst and water, placing the mixture in a reactor of an open system, and stirring the mixture in a dark place.

To reach N₂After the adsorption and desorption are balanced, a light energy excitation source (namely a light source) is used for carrying out a photocatalysis nitrogen fixation experiment. The light source can be sunlight or simulated sunlight. Wherein, a xenon lamp (power can be 100-500W, for example 500W) can be adopted to simulate sunlight. The illumination energy can be adjusted, and the illumination time can also be adjusted, for example, the illumination time can be 1-100 hours. In the invention, the photocatalysis nitrogen fixation process is normal temperature and normal pressure, and heating and pressurizing are not needed, so that the energy consumption can be reduced.

Test experiments with ammonia: the product from the test was sampled and tested for ammonia production. As an example, for example, 5mL of liquid is taken every 1h, placed in a colorimetric tube, diluted to 50mL, added with a Nassner reagent to perform a color reaction, and then measured with an ultraviolet spectrophotometer. According to the method for fixing nitrogen by photocatalysis, high nitrogen fixing efficiency (35 mu mol/g/h) is realized under the condition of simulating solar illumination, and a new thought is provided for the industrial catalytic synthesis of ammonia.

Compared with the Haber method which needs a large amount of energy consumption and has harsh reaction conditions, the catalytic reaction of the invention can realize higher yield and save energy under the condition of normal temperature and normal pressure illumination. And the reactant is water, and any toxic and harmful organic solvent is not required to be introduced, so that the pollution to the environment can be greatly reduced, and the environment friendliness of the reaction is improved. In addition, the method is simple and feasible, clean and efficient, does not need to add any oxidant or additive, consumes less energy and is easy to industrialize.

In the invention, based on BiOCl/MoO₂The composite catalyst is applied to photocatalysis nitrogen fixation, a proper catalyst is prepared through design, the composite catalyst is stirred and mixed until absorption and desorption are balanced, and N in the air is absorbed under the action of simulated solar illumination₂Reduction to NH₃The method can enable light energy to act on a large amount of catalysts without adding any sacrificial agent, and has a very good application prospect as a novel environment-friendly and energy-saving nitrogen fixation method.

The invention has the advantages that:

(1) the high photocatalytic nitrogen fixation technology is realized under the illumination condition;

(2) the reactant in the experimental process is only water, and an organic solvent which is toxic to the environment is not required to be introduced, and any cocatalyst, sacrificial agent and the like are not required to be added, so that the pollution to the environment is greatly reduced;

(3) the invention provides a novel idea for industrial synthesis of ammonia.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1: modification of MoO in different proportions₂The BiOCl material is subjected to a photocatalysis nitrogen fixation experiment in a water phase

(1) Dissolving a certain amount of mannitol (0.546g) in deionized water (25ml), stirring uniformly, and then adding a certain amount of Bi (NO)₃)₃(0.486g) and stirred uniformly. Finally, dropwise adding a saturated KCl solution, and stirring for 0.5h to obtain a mixed solution;

(2) transferring the obtained mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 160 ℃ for 4 hours, cooling, washing and drying to obtain a BiOCl nanosheet, wherein the size of the BiOCl nanosheet is 0.1-1 mu m, and the thickness of the BiOCl nanosheet is 10-100 nm;

(3) then adding a certain amount of MoCl₅(0.482g) is dissolved in ethanol solution (8ml), then a certain amount of deionized water and nitric acid solution (concentration is 50wt%, 2ml) are added, the mixture is stirred and mixed evenly, the mixture is transferred to a hydrothermal reaction kettle, hydrothermal treatment is carried out for 12h at 180 ℃, cooling, washing and drying are carried out, and MoO is obtained₂Nanosheets, said MoO₂The size of the nano sheet is 10-50 nm, and the thickness of the nano sheet is 1-10 nm;

(4) weighing BiOCl nanosheets and MoO with different mass ratios₂Nanosheets (among them, MoO)₂Mass concentrations of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 100%, respectively),respectively placing the mixture in a mortar, grinding for 0.5h to uniformly mix the mixture to obtain the BiOCl/MoO₂A composite material;

(5) the obtained BiOCl/MoO with different mass ratios₂After the composite material is fully ground, respectively adding 0.1g of powder into 200mL of water, placing the mixture in a 600mL reactor which is an open system, stirring the mixture for 0.5h in a dark place, and carrying out an adsorption and desorption balance experiment;

(6) turning on a xenon lamp, and illuminating for 1h under the illumination of a simulated solar light source;

(7) and (3) carrying out suction filtration, putting 50mL of filtrate into a colorimetric tube, adding 1mL of sodium potassium tartrate and 1mL of a Nardostachys reagent, shaking up, standing for 10-15 min, and detecting the yield of ammonia by using an ultraviolet spectrophotometer when the color development is stable.

FIG. 1 shows BiOCl/MoO synthesized in example 1₂XRD pattern and SEM of the composite material, showing BiOCl/MoO₂The composite material is successfully synthesized.

FIG. 2 shows BiOCl/MoO of different mass ratios obtained in example 1₂The nitrogen fixation efficiency graph obtained in the experiment of the composite material shows that MoO₂BiOCl/MoO with mass concentrations of 0wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50wt%, 60wt% and 100 wt% respectively₂NH of composite material₃Yields were 3.1. mu. mol/h/g, 18. mu. mol/h/g, 19.4. mu. mol/h/g, 21.2. mu. mol/h/g, 27.8. mu. mol/h/g, 35. mu. mol/h/g, 25.7. mu. mol/h/g and 5.1. mu. mol/h/g, respectively. Wherein MoO₂50wt% of BiOCl/MoO₂The nitrogen fixation performance is the best.

Example 2: BiOCl/MoO₂The composite material has optimal proportion of BiOCl to MoO₂1:1 cycle nitrogen fixation experiment:

(1) preparation of BiOCl/MoO₂Composite Material (same as example 1, BiOCl: MoO)₂The mass ratio is 1: 1);

(2) the obtained BiOCl/MoO₂After the composite material is fully ground, 0.1g of powder is added into 200mL of water and placed in a 600mL reactor, the reactor is an open system and stirred for 0.5h in the dark, and an adsorption and desorption balance experiment is carried out;

(3) turning on a xenon lamp, and illuminating for 1h under the illumination of a simulated solar light source;

(4) performing suction filtration, putting 50mL of filtrate into a colorimetric tube, adding 1mL of sodium potassium tartrate and 1mL of a Nashinou reagent, shaking uniformly, standing for 10-15 min, and detecting the yield of ammonia by using an ultraviolet spectrophotometer when color development is stable;

(5) mixing the obtained BiOCl/MoO₂The composite material was repeated as a cycle test from steps (2) to (4).

FIG. 3 shows BiOCl/MoO obtained in example 2₂Cycle test performance plot of ammonia production for composite showing BiOCl/MoO₂The nitrogen fixation efficiency of the composite material is basically about 35 mu mol/h/g, and the nitrogen fixation performance of the composite material is stable.

Comparative example 1: in contrast with MoO₂Loaded and MoO free₂Nitrogen fixation performance experiments for supported BiOCl-based catalysts:

(1) preparation of BiOCl/MoO₂Composite Material (same as example 1, BiOCl: MoO)₂The mass ratio is 1: 1);

(2) the obtained BiOCl/MoO₂The composite material (after being fully ground, 0.1g of powder is added into 200mL of water and placed in a 600mL reactor which is an open system and stirred for 0.5h in the dark for carrying out absorption and desorption balance experiments;

(3) turning on a xenon lamp, and illuminating for 1h under the illumination of a simulated solar light source;

(4) and (3) carrying out suction filtration, putting 50mL of filtrate into a colorimetric tube, adding 1mL of sodium potassium tartrate and 1mL of a Nardostachys reagent, shaking up, standing for 10-15 min, and detecting the yield of ammonia by using an ultraviolet spectrophotometer when the color development is stable.

FIG. 4 shows BiOCl catalyst and BiOCl/MoO in comparative example 1₂Comparative schematic of ammonia production from composite, BiOCl catalyst and BiOCl/MoO₂The yields of ammonia for the composite materials were 3.1. mu. mol/h/g and 35. mu. mol/h/g, respectively, and pure MoO can be seen with reference to FIG. 2₂The yield of ammonia from nanoplatelets (100 wt%) was only 5.1. mu. mol/h/g. Thus, BiOCl and MoO can be further demonstrated₂After compounding, the photocatalysis nitrogen fixation can be promoted synergistically.