A nickel phosphide supported polytriazine imide composite material, its preparation method and application

Abstract

The present invention relates to a nickel phosphide supported poly(triazine imide) composite material, a preparation method and an application thereof, belonging to the technical field of nickel-based catalyst materials. The composite material comprises a poly(triazine imide) support and nickel phosphide nanoparticles supported on the surface of the poly(triazine imide) support; the nickel phosphide nanoparticles are connected to the surface of the poly(triazine imide) support through a nitrogen-nickel chemical bond, and a metal-support electronic interaction is induced between the two. The composite material of the present invention is an organic polymer catalyst with excellent performance for the activation and conversion of molecular oxygen to generate hydrogen peroxide through metal-support electronic interaction, and has the advantages of simple and efficient preparation process and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based catalyst materials, and in particular to a nickel phosphide supported polytriazine imide composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen peroxide is a crucial chemical reagent and industrial product, which is widely used in multiple fields. Hydrogen peroxide has strong oxidizing properties and weak acidity, and is widely used as a bleaching agent, chemical raw material, disinfectant, water purifying agent, etc. In wastewater treatment and pollution control, hydrogen peroxide, as a strong oxidant, can effectively degrade organic pollutants in water bodies, and its by-product is only water, so it is regarded as a green and environmentally friendly oxidant. In recent years, the global demand for hydrogen peroxide has been steadily increasing, mainly due to the promotion of environmentally friendly technologies, the increasing demand for cleaning and disinfection, and its wide application in industries such as electronic manufacturing, papermaking, and water treatment. With the deepening of the concept of sustainable development, hydrogen peroxide will have a broader application prospect in the future, providing important support for the green transformation of various industries.

[0003] Currently, more than 95% of hydrogen peroxide globally is produced by the anthraquinone process. This method uses anthraquinone molecules as a circulating carrier to generate hydrogen peroxide through catalytic hydrogenation and oxidation reactions. In this process, anthraquinone molecules can be recycled multiple times, with highly selective chemical reactions and relatively high purity of the generated hydrogen peroxide, which is suitable for various industrial uses. However, the anthraquinone process has the disadvantages of high energy consumption, high equipment cost, and complex operation. The hydrogenation and oxidation reactions need to be carried out under high temperature and high pressure and involve the use of hydrogen, which poses extremely high technical requirements for the control of reaction conditions. Against the background of the global increasing concern about climate change and energy shortage, it has become particularly urgent to develop a green, efficient, and sustainable hydrogen peroxide production technology.

[0004] The preparation of hydrogen peroxide by photocatalysis has received extensive attention due to its clean, pollution-free, safe, and low-energy consumption characteristics. Among them, using solar energy as the only energy input, water and oxygen abundant in nature are catalytically reacted by a photocatalyst to generate hydrogen peroxide. However, currently, the generation efficiency of photocatalytic hydrogen peroxide is relatively low and cannot meet the requirements of conventional applications. The main reason restricting its generation efficiency is that the active sites of semiconductor photocatalysts have relatively weak or too strong activation intensity for molecular oxygen. On the one hand, it causes molecular oxygen not to be activated and converted into the hydrogen peroxide intermediate superoxide radical. On the other hand, it causes molecular oxygen to be over-activated, resulting in the cleavage of the O-O bond of molecular oxygen, and also unable to generate the hydrogen peroxide intermediate superoxide radical, leading to a low yield of hydrogen peroxide. In addition, the strong affinity between molecular oxygen and the active sites of semiconductor catalysts will cause the oxidation of the active sites, resulting in the inactivation of the active sites and reducing the service life of the catalyst material.

[0005] Based on the above background, how to design and develop an efficient semiconductor catalyst material with active sites for efficiently activating molecular oxygen and having a moderate interaction with molecular oxygen is the key to achieving efficient photocatalytic hydrogen peroxide generation. The development of the design and synthesis method of this catalyst material will have great energy and environmental significance and also have huge commercial prospects. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a nickel phosphide supported poly(triazine imide) composite material, a preparation method thereof, and an application thereof.

[0007] The first object of the present invention is to provide a nickel phosphide supported poly(triazine imide) composite material, which includes a poly(triazine imide) carrier and nickel phosphide nanoparticles loaded on the surface of the poly(triazine imide) carrier; the nickel phosphide nanoparticles are connected to the surface of the poly(triazine imide) carrier through N-Ni chemical bonds, and a metal-support electron interaction is induced between the nickel phosphide nanoparticles and the poly(triazine imide) carrier.

[0008] In some embodiments of the present invention, the loading amount of the nickel phosphide nanoparticles is 0.5 - 5.0 wt.%, and exemplarily, it can be 0.5 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, 5 wt.%, etc., or any interval value between any two values.

[0009] In some embodiments of the present invention, the preparation method of the nickel phosphide supported poly(triazine imide) composite material includes the following steps:

[0010] Mix a molten salt mixture with a poly(triazine imide) material precursor and perform a first heat calcination under an inert atmosphere to obtain a first powder;

[0011] Mix the first powder with a nickel source solution, perform solid-liquid separation to take the solid phase, and perform a second heat calcination on the obtained solid phase under a reducing atmosphere to obtain a second powder;

[0012] Perform a third heat calcination on the second powder and a phosphorus source under an inert atmosphere to obtain the nickel phosphide supported poly(triazine imide) composite material.

[0013] In some embodiments of the present invention, the molten salt mixture is selected from two or more of LiCl, NaCl, KCl, and CaCl2;

[0014] The poly(triazine imide) material precursor is selected from one or more of urea, melamine, thiourea, and dicyandiamide;

[0015] The mass ratio of the polytriazine imide material precursor to the molten salt mixture is (0.1 - 0.2):1.

[0016] In some embodiments of the present invention, the conditions for the first heating and calcination are: maintaining the temperature at 500 - 600 °C for 4 - 8 h. Exemplarily, the temperature can be 500 °C, 510 °C, 520 °C, 530 °C, 540 °C, 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, 600 °C, etc., or any interval value between any two values; the holding time can be 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h; the heating rate is 1.5 - 5.0 °C / min. Exemplarily, it can be 1.5 °C / min, 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, 5 °C / min, etc., or any interval value between any two values;

[0017] The non - active gas in the inert atmosphere is selected from nitrogen and / or argon.

[0018] In some embodiments of the present invention, the nickel source in the nickel source solution is selected from one or more of nickel nitrate, nickel chloride, and nickel acetylacetonate;

[0019] The solvent of the nickel source solution is selected from one or more of water, ethanol, or N,N - dimethylformamide;

[0020] The concentration of the nickel source solution is 10.0 - 50.0 mmol / L. Exemplarily, it can be 10.0 mmol / L, 15.0 mmol / L, 20.0 mmol / L, 25.0 mmol / L, 30.0 mmol / L, 35.0 mmol / L, 40.0 mmol / L, 45.0 mmol / L, 50.0 mmol / L, etc., or any interval value between any two values.

[0021] In some embodiments of the present invention, the dosage of the first powder in the nickel source solution is 1.0 - 10.0 g / L. Exemplarily, it can be 1.0 g / L, 2.0 g / L, 3.0 g / L, 4.0 g / L, 5.0 g / L, 6.0 g / L, 7.0 g / L, 8.0 g / L, 9.0 g / L, 10.0 g / L, etc., or any interval value between any two values;

[0022] The reducing atmosphere includes hydrogen and non - active gas;

[0023] The non - active gas is selected from nitrogen and / or argon;

[0024] The volume content of the hydrogen gas is 5.0 - 10.0%, and exemplarily, it can be 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, etc., or any interval value between any two numerical values;

[0025] The conditions for the second heating and calcination: the heating temperature is 300 - 400 °C, the heating time is 2 - 4 h. Exemplarily, the heating temperature can be 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, etc., the heating time is 2 h, 2.5 h, 3 h, 3.5 h, 4 h, etc., and the heating rate is 2 - 5 °C / min. Exemplarily, it can be 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, 5 °C / min, etc., or any interval value between any two numerical values.

[0026] In some embodiments of the present invention, the phosphorus source is selected from one or more of sodium hypophosphite, sodium hydrogen phosphate, and potassium hydrogen phosphate;

[0027] The conditions for the third heating and calcination: the heating temperature is 300 - 500 °C, the heating time is 0.5 - 3 h. Exemplarily, the heating temperature can be 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 450 °C, 500 °C, etc., the heating time is 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.; the heating rate is 2 - 5 °C / min. Exemplarily, it can be 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, 5 °C / min, etc., or any interval value between any two numerical values.

[0028] The second object of the present invention is to provide the application of the nickel phosphide supported polytriazine imide composite material in the photocatalytic activation and conversion of molecular oxygen.

[0029] In some embodiments of the present invention, the product of the activation and conversion of molecular oxygen is hydrogen peroxide;

[0030] The wavelength range of the light source in photocatalysis is 380 nm - 760 nm.

[0031] In the present invention, the regulation of active sites in the nickel phosphide supported polytriazine imide composite, and the metal-support electronic interaction induced between the active sites of nickel phosphide and the support polytriazine imide are used to regulate the molecular oxygen activation and conversion reaction. On the one hand, due to the presence of phosphorus atom ligands, the active sites of nickel phosphide can adsorb molecular oxygen in a Pauling-type adsorption configuration, which to a certain extent inhibits the cleavage of the O-O bond of molecular oxygen and promotes the activation and conversion of molecular oxygen into the hydrogen peroxide intermediate superoxide radical. On the other hand, the metal-support electronic interaction induced between the active sites of nickel phosphide and the support polytriazine imide induces the transfer of electrons from the polytriazine imide support to the active sites of nickel phosphide, promoting the activation and conversion process of molecular oxygen and the generation of superoxide radicals, and improving the hydrogen peroxide yield.

[0032] The equation for the activation and conversion of molecular oxygen in the present invention is:

[0033] O2 + 2H2O = 2H2O2;

[0034] The above technical solutions of the present invention have the following advantages compared with the prior art:

[0035] (1) Based on the reaction of photocatalytic hydrogen peroxide generation, which has the advantages of being green, sustainable and low-cost, compared with the traditional anthraquinone method, this system does not require large equipment and process investment and strict operation procedures. In the present invention, only sunlight is used as the energy input, and oxygen and water are used as raw materials to produce hydrogen peroxide under the catalysis of the nickel phosphide supported polytriazine imide composite. This process is green and environmentally friendly, and the raw materials are widely available, realizing the preparation of hydrogen peroxide at room temperature and normal pressure.

[0036] (2) The nickel phosphide supported polytriazine imide composite described in the present invention has excellent ability to separate photo-generated carriers, thus improving the photocatalytic efficiency. The active sites of nickel phosphide have moderate molecular oxygen activation ability due to the presence of phosphorus atom ligands. Molecular oxygen interacts with nickel phosphide in a Pauling-type adsorption configuration, promoting the activation and conversion of molecular oxygen into the hydrogen peroxide intermediate superoxide radical. At the same time, the metal-support electronic interaction between nickel phosphide and the polytriazine imide support induces the transfer of electrons from the polytriazine imide support to nickel phosphide, promoting the activation and conversion process of molecular oxygen, promoting the activation and conversion of molecular oxygen into superoxide radicals, and increasing the production of hydrogen peroxide. At the same time, the active sites of nickel phosphide can activate water molecules to generate protons, promoting the protonation process of superoxide radicals and increasing the production of hydrogen peroxide.

[0037] (3) The active sites in the nickel phosphide supported polytriazine imide composite described in the present invention can inhibit the cleavage of the O-O bond during the activation and conversion of molecular oxygen, have a high selectivity for hydrogen peroxide generation, and contribute to increasing the hydrogen peroxide yield.

[0038] Meanwhile, this system is not limited by the site and can be generated in situ and utilized in situ at the place where hydrogen peroxide is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to specific embodiments of the present invention in combination with the drawings, wherein,

[0040] Figure 1 HAADF-STEM images of the nickel phosphide supported poly(triazine imide) composite material prepared in Example 1 of the present invention and the poly(triazine imide) material in Comparative Example 2; wherein, a is the nickel phosphide supported poly(triazine imide) composite material prepared in Example 1, and b is the poly(triazine imide) material in Comparative Example 2;

[0041] Figure 2 XRD patterns of the nickel phosphide supported poly(triazine imide) composite material prepared in Example 1 of the present invention and the poly(triazine imide) material in Comparative Example 2;

[0042] Figure 3 XPS spectra of the nickel phosphide supported poly(triazine imide) composite material prepared in Example 1 of the present invention and the nickel supported poly(triazine imide) material in Comparative Example 1;

[0043] Figure 4 Performance of different catalyst materials in the photocatalytic activation and conversion of molecular oxygen to hydrogen peroxide in the present invention;

[0044] Figure 5 Performance of the nickel phosphide supported poly(triazine imide) composite material prepared in Example 1 of the present invention and the nickel supported poly(triazine imide) material in Comparative Example 1 in the photocatalytic activation and conversion of molecular oxygen to the hydrogen peroxide intermediate superoxide radical;

[0045] Figure 6 Charge distribution of the nickel phosphide supported poly(triazine imide) composite material and the nickel supported poly(triazine imide) composite material during the activation and conversion of molecular oxygen obtained by first-principles calculation (DFT) in the present invention; wherein, a is the nickel phosphide supported poly(triazine imide) composite material, and b is the nickel supported poly(triazine imide) composite material; nickel phosphide in the nickel phosphide supported poly(triazine imide) composite material obtains electrons from the poly(triazine imide) material, indicating that the metal-support electron interaction between nickel phosphide and the poly(triazine imide) material induces the transfer of electrons to nickel phosphide, which is beneficial to the activation and conversion of molecular oxygen and increases the hydrogen peroxide yield; nickel in the nickel supported poly(triazine imide) composite material transfers to the triazine imide material support, which is not conducive to the activation and conversion of molecular oxygen. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments are not intended to limit the present invention.

[0047] Example 1

[0048] This example provides a nickel phosphide supported polytriazine imide composite material, its preparation method and application.

[0049] (1). Preparation method of nickel phosphide supported polytriazine imide composite material, the specific steps are as follows:

[0050] 1. Prepare a polytriazine imide material to obtain a first powder: Grind and mix the molten salt mixture LiCl (4.5 g), KCl (5.5 g) and melamine (1.0 g) thoroughly in a mortar; Transfer the obtained mixture of solid powder to a porcelain boat and heat and calcine it in a nitrogen atmosphere. Heating conditions: Keep the temperature at 550 °C for 4 h, and the heating rate is 1.5 °C / min; Wait for the temperature to drop to room temperature to obtain the first powder.

[0051] 2. Dissolve nickel nitrate in deionized water to obtain a nickel source solution with a concentration of 10.0 mmol / L.

[0052] 3. Put 500 mg of the first powder into the obtained 50 mL nickel source solution, stir and mix well, then filter to obtain a solid, and then dry it in a vacuum drying oven (60 °C) for 12 h to obtain a second powder.

[0053] 4. Transfer 200 mg of the second powder to a porcelain boat and heat and calcine it in an argon-hydrogen mixed gas atmosphere to obtain a third powder; Among them, the volume ratio of hydrogen is 5.0%, and the heating and calcining conditions are: the heating temperature is 300 °C, the heating time is 4 h, and the heating rate is 2 °C / min.

[0054] 5. Transfer 50 mg of the third powder and 250 mg of sodium hypophosphite powder to a porcelain boat and heat and calcine it in an argon atmosphere. Among them, the heating and calcining conditions are: the heating temperature is 400 °C, the heating time is 0.5 h, and the heating rate is 5 °C / min; Obtain the nickel phosphide supported polytriazine imide composite material; The loading amount of the nickel phosphide nanoparticles is 3.46 wt.%. Characterize the structure of this material, and the results are shown in Figure 1 、 Figure 2 and Figure 3 .

[0055] The HAADF-STEM image of the nickel phosphide supported polytriazine imide composite material obtained in this example is as shown in Figure 1 shown, the XRD characterization results are as shown in Figure 2 shown, the XPS characterization results are as shown inFigure 3 As shown. It can be seen from the above figures that nickel phosphide is successfully loaded on the surface of the polytriazine imide support, and the loading of nickel phosphide has no significant effect on the crystal structure of the polytriazine imide support.

[0056] (2) Photocatalytic molecular oxygen activation and conversion reaction experiment

[0057] The photocatalytic molecular oxygen activation and conversion performance of the obtained nickel phosphide-loaded polytriazine imide composite material was evaluated in a PCX-50C Discver multi-channel photocatalytic reaction device (Beijing Perfectlight Technology Co., Ltd., China). The device is equipped with an LED light source with a wavelength range of 380 nm to 760 nm, and can accurately output the AM 1.5G solar spectrum within this range for the photocatalytic molecular oxygen activation and conversion experiment. The evaluation results were the average of 3 tests.

[0058] Specific operation: Add 0.5 g / L of the nickel phosphide-loaded polytriazine imide composite material catalyst of this example to 30.0 mL of deionized water, and stir and react it under the illumination of the photocatalytic device for 1.0 h. Subsequently, take out 2.0 mL of the reaction suspension from the reaction vessel and filter it with a 0.22 μm aqueous filter membrane. The hydrogen peroxide concentration of the obtained solution was measured by the DPD-POD colorimetric method. The experimental results are shown in Figure 4 , and it can be seen from the figure that the metal-support electronic interaction between nickel phosphide and polytriazine imide can effectively activate molecular oxygen and convert it into hydrogen peroxide.

[0059] Example 2

[0060] The preparation method is the same as that of Example 1, except that the nickel source solution is replaced with a nickel chloride solution dissolved in deionized water to obtain a 25.0 mmol / L nickel source solution.

[0061] (2) Photocatalytic molecular oxygen activation and conversion reaction experiment

[0062] The method for evaluating the photocatalytic molecular oxygen activation and conversion performance of the material in this example is the same as that of Example 1. The efficiency of the nickel phosphide-loaded polytriazine imide composite material catalyst for the activation and conversion of molecular oxygen to generate hydrogen peroxide is as shown in Figure 4 shown.

[0063] Example 3

[0064] The preparation method is the same as that of Example 1, except that 50 mg of the third powder and 250 mg of sodium hypophosphite powder are transferred to a porcelain boat and heated and calcined under an argon atmosphere. The conditions for heating and calcining are: the heating temperature is 400 °C, the heating time is 3.0 h, and the heating rate is 5 °C / min.

[0065] (2) Photocatalytic Molecular Oxygen Activation and Transformation Reaction Experiment

[0066] In this example, the method for evaluating the photocatalytic molecular oxygen activation and transformation performance of the nickel phosphide supported polytriazine imide composite catalyst is the same as that in Example 1. The efficiency of the nickel phosphide supported polytriazine imide composite catalyst for the activation and transformation of molecular oxygen to generate hydrogen peroxide is as Figure 4 shown.

[0067] Comparative Example 1

[0068] In this comparative example, a nickel supported polytriazine imide composite material was used as a control.

[0069] (1) Preparation Method of Nickel Supported Polytriazine Imide Composite Material

[0070] 1. Prepare a polytriazine imide material to obtain the first powder: Thoroughly grind and mix the molten salt mixture LiCl (4.5 g), KCl (5.5 g), and melamine (1.0 g) in a mortar; transfer the obtained solid powder of the mixture to a porcelain boat and heat and calcine it in a nitrogen atmosphere. The conditions for heating and calcining are: keep the temperature at 550 °C for 4 h, and the heating rate is 1.5 °C / min; wait for the temperature to drop to room temperature to obtain the first powder.

[0071] 2. Dissolve nickel nitrate in deionized water to obtain a nickel source solution with a concentration of 10.0 mmol / L.

[0072] 3. Put 500 mg of the first powder into the obtained 50 mL nickel source solution, stir and mix well, then filter to obtain a solid, and then dry it in a vacuum drying oven (60 °C) for 12 h to obtain the second powder.

[0073] 4. Transfer 200 mg of the second powder to a porcelain boat and heat and calcine it in an argon-hydrogen mixed gas atmosphere, where the volume ratio of hydrogen is 5.0%. The heating conditions are: the heating temperature is 300 °C, the heating time is 4 h, and the heating rate is 2 °C / min; finally, a nickel supported polytriazine imide composite material is obtained, and the structure of this material is characterized. The results are shown in Figure 3 .

[0074] (2) Photocatalytic Molecular Oxygen Activation and Transformation Reaction Experiment

[0075] In this comparative example, the method for evaluating the photocatalytic molecular oxygen activation and transformation performance of the material is the same as that in Example 1. The efficiency of the nickel supported polytriazine imide composite catalyst for the activation and transformation of molecular oxygen to generate hydrogen peroxide is as Figure 4 shown.

[0076] Comparative Example 2

[0077] In this comparative example, a polytriazine imide material was used as a control.

[0078] (1) Preparation method of polytriazine imide material

[0079] Mix molten salt mixture LiCl (4.5 g) and KCl (5.5 g) and melamine (1.0 g) thoroughly in a mortar; transfer the obtained solid powder of the mixture to a porcelain boat and heat and calcine it in a nitrogen atmosphere. The heat and calcination conditions are: keep the temperature at 550 °C for 4 h, and the heating rate is 1.5 °C / min; wait for the temperature to drop to room temperature to obtain the polytriazine imide material. The characterization results of the obtained material are shown in Figure 1 and Figure 2 , Figure 1 Compared with Figure a in Figure 1 Many uniform particles are newly added and loaded on the polytriazine imide material in Figure b, indicating that nickel phosphide is successfully loaded in Example 1.

[0080] (2) Photocatalytic molecular oxygen activation and conversion reaction experiment

[0081] In this comparative example, the evaluation method of the photocatalytic molecular oxygen activation and conversion performance of the obtained polytriazine imide material is the same as that in Example 1. The efficiency of the catalyst for the activation and conversion of molecular oxygen to generate hydrogen peroxide is as shown in Figure 4 shown.

[0082] Comparative Example 3

[0083] This comparative example uses phosphated polytriazine imide material as a control.

[0084] (1) Preparation method of phosphated polytriazine imide material

[0085] Prepare a polytriazine imide material to obtain the first powder: Mix molten salt mixture LiCl (4.5 g) and KCl (5.5 g) and melamine (1.0 g) thoroughly in a mortar; transfer the obtained solid powder of the mixture to a porcelain boat and heat and calcine it in a nitrogen atmosphere. The heat and calcination conditions are: keep the temperature at 550 °C for 4 h, and the heating rate is 1.5 °C / min; wait for the temperature to drop to room temperature to obtain the first powder.

[0086] Transfer 50 mg of the first powder and 250 mg of sodium hypophosphite powder to a porcelain boat and heat and calcine them in an argon atmosphere. The heating conditions are: the heating temperature is 400 °C, the heating time is 0.5 h, and the heating rate is 5 °C / min; obtain the phosphated polytriazine imide material.

[0087] (2) Photocatalytic molecular oxygen activation and conversion reaction experiment

[0088] The method for evaluating the photocatalytic molecular oxygen activation and conversion performance of the phosphated polytriazine imide material catalyst obtained in this comparative example is the same as that in Example 1. The efficiency of the molecular oxygen activation and conversion of the phosphated polytriazine imide material catalyst to produce hydrogen peroxide is as Figure 4 shown.

[0089] From Figure 2 and Figure 3 it can be seen that compared with Comparative Example 2, characteristic peaks corresponding to nickel phosphide appear in the phosphated polytriazine imide material catalyst obtained in Example 1, indicating that nickel phosphide exists in the composite material in Example 1.

[0090] From Figure 4 it can be seen that compared with the comparative examples, the nickel phosphide-loaded polytriazine imide composite materials prepared by different methods in Examples 1-3 all showed the activity of molecular oxygen activation and conversion to hydrogen peroxide, while Comparative Examples 1-3 all showed relatively low activity of molecular oxygen activation and conversion to hydrogen peroxide, indicating that nickel phosphide is the key to efficiently generating hydrogen peroxide.

[0091] From Figure 5 it can be seen that the nickel phosphide-loaded polytriazine imide composite material in Example 1 showed excellent activity of molecular oxygen activation and conversion to the hydrogen peroxide intermediate superoxide radical, while the nickel-loaded polytriazine imide composite material in Comparative Example 1 showed relatively low activity of molecular oxygen activation and conversion to the hydrogen peroxide intermediate superoxide radical, indicating that nickel phosphide is the main active site for activating molecular oxygen to form superoxide radicals. Due to the presence of phosphorus atom coordination, the nickel phosphide active site can moderately activate molecular oxygen to generate superoxide radicals, thus resulting in a higher activity of molecular oxygen activation and conversion to produce hydrogen peroxide; while nickel over-activates molecular oxygen, causing the O-O bond of molecular oxygen to break and unable to generate superoxide radicals, further reducing the production efficiency of hydrogen peroxide.

[0092] Obviously, the above examples are only for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. Application of a nickel phosphide-loaded polytriazine imide composite material in photocatalytic production of hydrogen peroxide; the nickel phosphide-loaded polytriazine imide composite material comprises a polytriazine imide carrier, and nickel phosphide nanoparticles loaded on the surface of the polytriazine imide carrier; the nickel phosphide nanoparticles are connected to the surface of the polytriazine imide carrier via N-Ni chemical bonds, and metal-carrier electronic interactions are induced between the nickel phosphide nanoparticles and the polytriazine imide carrier.

2. The use according to claim 1, characterized in that: The loading amount of the nickel phosphide nanoparticles is 0.5 wt.% to 5.0 wt.%.

3. The use according to claim 1, characterized in that: The preparation method of the nickel phosphide-loaded polytriazine imide composite material comprises the following steps: The molten salt mixture is mixed with a polytriazine imide material precursor, and subjected to a first heating and calcining in an inert atmosphere to obtain a first powder; The first powder is mixed with a nickel source solution, and solid-liquid separation is performed to obtain a solid phase, and the obtained solid phase is heated and calcined for a second time under a reducing atmosphere to obtain a second powder; The second powder and the phosphorus source are heated and calcined for the third time under an inert atmosphere to obtain the nickel phosphide-loaded polytriazine imide composite material.

4. The use according to claim 3, characterized in that: The molten salt mixture is selected from two or more of LiCl, NaCl, KCl and CaCl2; The polytriazineimide material precursor is selected from one or more of urea, melamine, thiourea and dicyandiamide; The mass ratio of the polytriazine imide material precursor to the molten salt mixture is (0.1-0.2):

1.

5. The use according to claim 3, characterized in that: The conditions of the first heating and calcining are: 500-600°C for 4-8 hours, and the heating rate is 1.5-5.0°C / min; The inert gas in the inert atmosphere is selected from nitrogen and / or argon.

6. The use according to claim 3, characterized in that: The nickel source in the nickel source solution is selected from one or more of nickel nitrate, nickel chloride, and nickel acetylacetonate; The solvent of the nickel source solution is selected from one or more of water, ethanol or N,N-dimethylformamide; The concentration of the nickel source solution is 10.0 ~ 50.0 mmol / L.

7. The use according to claim 3, characterized in that: The dosage of the first powder in the nickel source solution is 1.0 to 10.0 g / L; The reducing atmosphere includes hydrogen and an inert gas; The inert gas is selected from nitrogen and / or argon; The volume content of the hydrogen is 5.0 to 10.0%; The conditions for the second heating and calcination are: heating temperature is 300 ~ 400 ℃, heating time is 2 ~ 4 h, and heating temperature rise rate is 2 ~ 5 ℃ / min.

8. The use according to claim 3, characterized in that: The phosphorus source is selected from one or more of sodium hypophosphite, sodium hydrogen phosphate, and potassium hydrogen phosphate; The conditions for the third heating and calcination are: heating temperature is 300 ~ 500 ℃, heating time is 0.5 ~ 3 h, and heating temperature rise rate is 2 ~ 5 ℃ / min.

9. The use according to claim 1, characterized in that: The wavelength range of the light source in photocatalysis is 380 nm ~ 760 nm.

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