Preparation method of photo-storage integrated catalyst and application of photo-storage integrated catalyst in electro-synthesis of hydrogen peroxide

Abstract

The invention discloses a preparation method suitable for a photo-storage integrated catalyst and application of the photo-storage integrated catalyst in electrosynthesis of hydrogen peroxide, and relates to the technical field of electrosynthesis of hydrogen peroxide. The method comprises the steps that nickel salt, triethylene diamine and terephthalic acid are dispersed in N, N-dimethylformamide respectively, and three solutions are obtained; adding a nickel salt solution and a triethylene diamine solution into the terephthalic acid solution to obtain a precursor solution; placing the precursor solution in a high-pressure reaction kettle, sealing, and reacting according to a set temperature and time to obtain a turbid liquid; and naturally cooling the reaction kettle to room temperature, centrifugally collecting a product in the turbid liquid, respectively washing with absolute ethyl alcohol and deionized water, and carrying out vacuum drying to obtain the catalyst suitable for light-storage integration. The catalyst provided by the invention has the advantages of high yield of catalytically produced hydrogen peroxide, good stability, simple and convenient preparation process and the like, and is suitable for light-storage integrated application of preparing green chemicals from intermittent renewable energy sources.

Description

Technical Field

[0001] This application relates to the field of electrochemical synthesis of hydrogen peroxide technology, specifically to a method for preparing a photovoltaic-storage integrated catalyst and its application in electrochemical synthesis of hydrogen peroxide. Background Technology

[0002] Photovoltaic-storage integrated technology provides stable power input for electrochemical synthesis through the synergistic regulation of photovoltaic power generation and energy storage systems. However, a key contradiction remains in its deep integration with the electrolysis system: the charge and discharge response rate of the energy storage device is difficult to precisely match with the dynamic load requirements of the electrolyzer, resulting in secondary energy loss; simultaneously, traditional catalysts are prone to passivation of active sites or structural degradation under fluctuating current densities, leading to a significant decrease in product selectivity and severely restricting the stability of continuous production. This dynamic mismatch between energy supply and the catalytic system has become the core bottleneck hindering the large-scale application of photovoltaic-storage electrosynthesis technology. If electrochemical synthesis technology can be deeply coupled with photovoltaic-storage integrated technology, it is expected to further promote green and low-carbon transformation and achieve optimization of the entire chain from energy production to chemical synthesis.

[0003] hydrogen peroxide ( Anthraquinone, as a core chemical in modern industrial systems, has applications spanning paper bleaching, electronic etching, environmental remediation, and medical disinfection. Currently, mainstream production processes rely on the energy-intensive and polluting anthraquinone process, which requires multi-stage hydrogenation / oxidation cycles and generates large amounts of wastewater, making it difficult to meet the demands of green and low-carbon transformation. Electrochemical oxygen reduction synthesis (… ) Through green electricity, water and oxygen are directly converted to produce In theory, it can achieve zero carbon emissions and modular production, but in actual industrialization, it faces bottlenecks such as low catalytic efficiency, strong dependence on precious metals, and catalyst deactivation under current fluctuations, resulting in high energy consumption costs.

[0004] Current research on the electrosynthesis of hydrogen peroxide largely focuses on noble metal or complex modified catalytic systems, which are cumbersome and costly to prepare. While non-noble metal and carbon-based catalysts can reduce material costs, they still face challenges such as insufficient activity, poor stability, and difficulty in microstructure control. Developing novel material systems that combine high catalytic performance, tolerance to dynamic operating conditions, and cost-effectiveness is crucial for advancing the green synthesis of hydrogen peroxide via electrochemical methods. The key breakthrough direction for industrialization. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a photovoltaic-storage integrated catalyst and its application in the electrosynthesis of hydrogen peroxide, which still exhibits high selectivity, excellent stability, and high Faraday efficiency under fluctuating current densities.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of this invention discloses a method for preparing a photocatalyst suitable for integrated photovoltaic and energy storage, comprising the following steps: Nickel salt, triethylenediamine, and terephthalic acid were dispersed in N, N, and N, respectively, according to a predetermined molar concentration ratio. In dimethylformamide, nickel salt solution, triethylenediamine solution and terephthalic acid solution are obtained; A nickel salt solution and a triethylenediamine solution were added to a terephthalic acid solution to obtain a precursor solution. The precursor solution was placed in a high-pressure reactor, sealed, and reacted according to the set temperature and time to obtain a suspension. After the reactor is allowed to cool naturally to room temperature, the product in the suspension is collected by centrifugation, washed with anhydrous ethanol and deionized water respectively, and then vacuum dried to obtain a catalyst suitable for integrated photovoltaic and energy storage.

[0008] Preferably, the dispersion method includes at least one of ultrasonication, grinding, and stirring.

[0009] Preferably, when the dispersion method is ultrasonic or stirring, the dispersion time is 10-30 min.

[0010] Preferably, the nickel salt is any one of nickel nitrate, nickel sulfate, or nickel chloride.

[0011] Preferably, the molar concentration ratio of the nickel salt:triethylenediamine:terephthalic acid is in the range of 3:1:1 to 3:1:2.

[0012] Preferably, the nickel salt, triethylenediamine, and terephthalic acid are reacted with N,N The molar concentration ratio of dimethylformamide is 15:5:15:3.

[0013] Preferably, the reaction temperature of the high-pressure reactor is set to 120~140℃.

[0014] Preferably, the high-pressure reactor is set to operate for 14 to 24 hours.

[0015] The second aspect of the present invention discloses a catalyst suitable for integrated photovoltaic and energy storage, which is prepared by the preparation method for integrated photovoltaic and energy storage catalysts described in the first aspect.

[0016] The third aspect of this invention discloses the application of the catalyst suitable for integrated photovoltaic-energy storage as described in the second aspect in the electrosynthesis of hydrogen peroxide. A silicon solar panel is used as the photovoltaic module in the integrated photovoltaic-energy storage system. The photovoltaic module is connected to an electrolysis module to form a closed loop. In the electrolysis module, carbon paper loaded with a catalyst suitable for integrated photovoltaic-energy storage is used as the cathode, and a catalyst loaded with Pt / C or... The carbon paper is used as the anode, and electrolysis is carried out in an alkaline electrolyte to produce hydrogen peroxide.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1) This invention prepares a nickel metal-organic framework catalyst for the electrosynthesis of hydrogen peroxide by a solvothermal method. The catalyst forms a three-dimensional network structure through the self-assembly of nickel ions and organic ligands, which has a high specific surface area, uniformly distributed nickel active sites and tunable electronic structure, thereby improving the hydrogen peroxide selectivity of the electrosynthesis of hydrogen peroxide. The selectivity exceeds 92% in the range of 0.3 to 0.7 V, giving the catalyst high catalytic performance. The catalyst is suitable for the electrosynthesis of hydrogen peroxide.

[0018] 2) The redox activity of nickel and the synergistic effect of ligands in the nickel metal-organic framework catalyst prepared by this invention further optimize the catalytic pathway, enabling it to exhibit excellent Faraday efficiency at different current densities and maintain long-term stability at high current densities. It is suitable for the electro-synthesis of hydrogen peroxide module in a distributed photovoltaic-storage integrated system.

[0019] 3) The catalyst preparation method provided by this invention has a simple preparation procedure, low cost, and can achieve batch preparation, thus having excellent market and economic value. Attached Figure Description

[0020] Figure 1 The current-time curves of a photovoltaic-driven electrolysis system (PV-EC) and a conventional electrolysis system (EC) are shown in multiple cycles. Figure 2 Scanning electron microscope image of the nickel metal-organic framework catalyst prepared in Example 1; Figure 3 Linear sweep voltammetry plot of the nickel metal-organic framework catalyst prepared in Example 1; Figure 4 The diagram shows the electron transfer number and hydrogen peroxide selectivity of the nickel metal-organic framework catalyst prepared in Example 1. Figure 5 The cyclic voltammogram is shown for the nickel metal-organic framework catalyst prepared in Example 1. Figure 5 Figure 5(a) shows the cyclic voltammetry curves at different scan rates, and Figure 5(b) shows the linear relationship between current density and scan rate. Figure 6 The image shows the electrochemical impedance spectroscopy of the nickel metal-organic framework catalyst prepared in Example 1.

[0021] Figure 7 This is a graph showing the long-term stability test of the nickel metal-organic framework catalyst prepared in Example 1 under high current density. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0023] An embodiment of the present invention discloses a method for preparing a photocatalyst suitable for integrated photovoltaic and energy storage, comprising the following steps: Step 1: Disperse the predetermined amounts of nickel salt, triethylenediamine, and terephthalic acid separately in N, N In dimethylformamide (DMF), nickel salt solution, triethylenediamine solution and terephthalic acid solution are obtained; In a preferred but non-limiting embodiment of the present invention, the dispersion method includes at least one of ultrasonication, grinding, and stirring; when the dispersion method is ultrasonication or stirring, the dispersion time is 10 to 30 minutes.

[0024] More preferably, the nickel salt is any one of nickel nitrate, nickel sulfate, or nickel chloride.

[0025] More preferably, the molar concentration ratio of the nickel salt:triethylenediamine:terephthalic acid is in the range of 3:1:1 to 3:1:2.

[0026] More preferably, the nickel salt, triethylenediamine, and terephthalic acid are reacted with N,N The molar concentration ratio of dimethylformamide (DMF) is 15:5:15:3.

[0027] It is worth noting that triethylenediamine and terephthalic acid were selected in this application because of their unique coordination ability and structural advantages. The two can form a stable 3D framework with nickel ions and have a specific pore structure.

[0028] The triethylenediamine molecule contains multiple nitrogen atoms, which have strong coordination ability. The carbon chain length and spatial structure enable it to form more suitable pore structures and channels when coordinating with nickel ions and terephthalic acid. The bidentate coordination ability can construct columnar structures perpendicular to the two-dimensional layer to form three-dimensional channels. Terephthalic acid, a commonly used aromatic dicarboxylic acid, has two carboxyl groups located at the para position of the benzene ring during the synthesis of metal-organic frameworks. This specific spatial arrangement allows it to form frameworks with specific dimensions and topological structures with nickel ions and triethylenediamine. Its long carboxylate group can form extended coordination chains with metal ions, providing an ideal organic ligand for constructing metal-organic frameworks with large surface areas and regular channels.

[0029] Compared with other phthalic acids such as phthalic acid or isophthalic acid, terephthalic acid exhibits superior performance in terms of thermal and chemical stability. Its rigid benzene ring structure endows the framework with high stability, enabling the catalyst to have long-term stability at high current densities to meet the needs of industrial applications.

[0030] Compared to existing carbon-based catalysts, which suffer from uneven active sites, insufficient stability, and lack of precise control over active sites, the catalyst prepared by this method achieves atomic-level uniformity of active sites and possesses advantages such as tunable active sites, high hydrogen peroxide selectivity, and long-term stability under high current density. Experimental verification by the inventors shows that the combination and appropriate ratio of triethylenediamine and terephthalic acid with nickel salts results in a nickel metal-organic framework exhibiting excellent thermal and chemical stability, meeting application requirements.

[0031] Step 2: Add the nickel salt solution and triethylenediamine solution sequentially to the terephthalic acid solution to obtain the precursor solution; Step 3: Place the precursor solution in a stainless steel autoclave lined with polytetrafluoroethylene and seal it. Then place it in a constant temperature oven and react it at the set temperature for the set time. Furthermore, the reaction temperature in the reactor is 120~140℃, and the reaction time is 14~24 h.

[0032] Step 4: After the reaction vessel from Step 3 has cooled naturally to room temperature, collect the product from the suspension by centrifugation. Wash the product thoroughly with anhydrous ethanol and deionized water, and then vacuum dry to obtain the Ni-MOF catalyst suitable for integrated photovoltaic and energy storage. .

[0033] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0034] Example 1 Step 1: Disperse 1.24 mmol nickel nitrate, 0.42 mmol triethylenediamine, and 1.26 mmol terephthalic acid separately in a 10 ml container of N, N Three solutions were obtained in a beaker containing dimethylformamide (DMF); Step 2: Slowly add nickel nitrate solution and triethylenediamine solution sequentially to terephthalic acid solution to obtain precursor solution; Step 3: Place the precursor solution in a 50 ml stainless steel autoclave lined with polytetrafluoroethylene and seal it. Then place it in a constant temperature oven at 120°C for 24 hours. Step 4: After the reaction vessel from Step 3 has cooled naturally to room temperature, the product in the suspension is collected by centrifugation, washed three times with anhydrous ethanol and deionized water respectively, and dried under vacuum for 12 h to obtain the Ni-MOF catalyst.

[0035] like Figure 2 As shown, the nickel metal-organic framework catalyst obtained in Example 1 has a three-dimensional network structure. The Faradaic efficiency of the Ni-MOF catalyst prepared in Example 1 at different current densities is shown in Table 1 below.

[0036] Table 1

[0037] As shown in Table 1, the Ni-MOF catalyst exhibits excellent Faradaic efficiency at different current densities. This indicates that the nickel metal-organic framework electrosynthetic hydrogen peroxide catalyst prepared in this invention has excellent electrosynthetic hydrogen peroxide performance and is suitable for photovoltaic-driven preconditions. It can solve the technical problem that traditional catalysts are prone to active site passivation or structural degradation under fluctuating current densities, leading to a significant decrease in product selectivity and severely restricting the stability of continuous production.

[0038] The nickel metal-organic framework catalyst obtained in Example 1 of this invention can be used for the electrosynthesis of hydrogen peroxide. The inventors' team investigated the catalytic performance of this catalyst using an IVIUM rotating ring disk electrode and a CHI 730E electrochemical workstation. (1) 5 mg of catalyst was dispersed in a mixed solution of 1 ml water, isopropanol, and Nafion. After ultrasonic dispersion, 5 μL of the solution was evenly dropped onto a rotating ring electrode and allowed to air dry. Then, 0.1 M sodium hydroxide solution was added to the electrolytic cell, oxygen was introduced, and LSV scanning was performed using an electrochemical workstation at an electrode rotation speed of 1600 rpm. The results are as follows: See Figure 1 It can be seen that the photovoltaic-electrochemical system (PV-EC) using the nickel metal-organic framework catalyst obtained in Example 1 has a larger output current fluctuation compared to the electrochemical system (EC). Therefore, the nickel metal-organic framework catalyst obtained in Example 1 exhibits excellent Faraday efficiency at different current densities and is suitable for photovoltaic-electrochemical systems.

[0039] See Figure 3 The ring current (Ic) of the prepared nickel metal-organic framework catalyst can be obtained. ring ) and disk current density (j disk It can be seen that, compared with the commercial carbon catalyst XC72, the nickel metal-organic framework catalyst exhibits good electrochemical stability and activity in the potential range of 0.30 V to 0.90 V.

[0040] See Figure 4 ,pass Figure 3 The loop current (I) in ring ) and disk current (j disk The selectivity and electron transfer number of hydrogen peroxide under different voltages were obtained by density calculation. The results showed that the nickel metal-organic framework catalyst had an average selectivity of 93% and an average electron transfer number of 2.1 in the voltage range of 0.3-0.7V (vs. RHE). In comparison, the commercial carbon catalyst XC72 had an average selectivity of 83% and an average electron transfer number of 2.4.

[0041] See Figure 7 ,exist The catalyst remained stable for up to 40 hours at the current density, demonstrating the excellent long-term stability of the nickel metal-organic framework catalyst obtained in Example 1 at industrial-grade current densities.

[0042] (2) Disperse 5 mg of catalyst in a mixed solution of 1 ml water, isopropanol and Nafion. After ultrasonic dispersion, take 100 μL of the solution and drop it evenly onto the carbon paper electrode, and let it air dry. A two-chamber electrolytic cell was used in the experiment. The diaphragm was an anion exchange membrane. The carbon paper supported on the nickel metal-organic framework catalyst was used as the working electrode, silver / silver chloride was used as the reference electrode, and a platinum mesh electrode was used as the counter electrode. Then, 0.1 M sodium hydroxide solution was added to the electrolytic cell, oxygen was introduced, and CV scanning and EIS testing were performed using an electrochemical workstation.

[0043] The results are as follows Figure 5 As shown, Figure 5 (a) shows a high current density and a large curve area. Figure 5 (b) shows a large slope in the linear relationship between current density and scan rate, indicating that the catalyst described in this application has good electrochemical activity. Figure 6 As shown, the impedance spectrum changes little under different voltages, indicating that the catalyst has good stability.

[0044] In summary, the catalyst prepared by the method described in this invention can solve the problems of catalyst active site passivation and structural deterioration caused by unstable current density in photovoltaic-driven electrolysis systems, and can also solve the problems of low catalyst activity and selectivity in existing technologies.

[0045] Comparative Example 1 The catalyst was prepared according to the method of Example 1, except that cobalt nitrate was added instead of nickel nitrate.

[0046] 5 mg of catalyst was dispersed in a mixed solution of 1 ml water, isopropanol, and Nafion. After ultrasonic dispersion, 5 μL of the solution was evenly dropped onto a rotating ring electrode and allowed to air dry. Then, 0.1 M sodium hydroxide solution was added to the electrolytic cell, oxygen was introduced, and LSV scanning was performed using an electrochemical workstation at an electrode rotation speed of 1600 rpm.

[0047] Through the loop current (I) ring The selectivity and electron transfer number of hydrogen peroxide under different voltages were obtained using disk current density. The calculation results showed that the cobalt metal-organic framework catalyst had an average selectivity of 23% and an average electron transfer number of 3.6 in the voltage range of 0.3-0.7 V (vs. RHE).

[0048] Compared with Example 1, the difference is significant, indicating that the cobalt metal-organic framework catalyst has low catalytic activity and reaction selectivity.

[0049] Example 2 of the present invention discloses a catalyst suitable for integrated photovoltaic and energy storage, which is prepared by the method for preparing a catalyst suitable for integrated photovoltaic and energy storage as described in Example 1.

[0050] Example 3 of the present invention discloses an application of electrosynthetic hydrogen peroxide, using a catalyst suitable for photovoltaic-storage integration as described in Example 2.

[0051] Specifically, commercial silicon solar panels are used as photovoltaic modules in the integrated photovoltaic and energy storage system, and the photovoltaic modules are connected to the electrolysis module to form a closed loop.

[0052] In the electrolysis module, carbon paper with a catalyst suitable for integrated photovoltaic and energy storage is used as the cathode, and the load used is Pt / C or... The carbon paper is used as the anode, and electrolysis is carried out in an alkaline electrolyte to produce hydrogen peroxide.

[0053] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1) This invention prepares a nickel metal-organic framework catalyst for the electrosynthesis of hydrogen peroxide by a solvothermal method. The catalyst forms a three-dimensional network structure through the self-assembly of nickel ions and organic ligands, which has a high specific surface area, uniformly distributed nickel active sites and tunable electronic structure, thereby improving the hydrogen peroxide selectivity of the electrosynthesis of hydrogen peroxide. The selectivity exceeds 92% in the range of 0.3 to 0.7 V, giving the catalyst high catalytic performance. The catalyst is suitable for the electrosynthesis of hydrogen peroxide.

[0054] 2) The redox activity of nickel and the synergistic effect of ligands in the nickel metal-organic framework catalyst prepared by this invention further optimize the catalytic pathway, enabling it to exhibit excellent Faraday efficiency at different current densities and maintain long-term stability at high current densities. It is suitable for the electro-synthesis of hydrogen peroxide module in a distributed photovoltaic-storage integrated system.

[0055] 3) The catalyst preparation method provided by this invention has a simple preparation procedure, low cost, and can achieve batch preparation, thus having excellent market and economic value.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a photovoltaic-storage integrated catalyst, characterized in that, Includes the following steps: Nickel salt, triethylenediamine, and terephthalic acid were dispersed in N, N, and N, respectively, according to a predetermined molar concentration ratio. In dimethylformamide, nickel salt solution, triethylenediamine solution and terephthalic acid solution are obtained; A nickel salt solution and a triethylenediamine solution were added to a terephthalic acid solution to obtain a precursor solution. The precursor solution was placed in a high-pressure reactor, sealed, and reacted according to the set temperature and time to obtain a suspension. After the reactor is allowed to cool naturally to room temperature, the product in the suspension is collected by centrifugation, washed with anhydrous ethanol and deionized water respectively, and then vacuum dried to obtain a catalyst suitable for integrated photovoltaic and energy storage.

2. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The dispersion method includes at least one of ultrasonication, grinding, and stirring.

3. The method for preparing a photovoltaic-storage integrated catalyst according to claim 2, characterized in that, When the dispersion method is ultrasonic or stirring, the dispersion time is 10-30 min.

4. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The nickel salt is any one of nickel nitrate, nickel sulfate, or nickel chloride.

5. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The molar concentration ratio of the nickel salt, triethylenediamine, and terephthalic acid is set to be in the range of 3:1:1 to 3:1:

2.

6. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The nickel salt, triethylenediamine, and terephthalic acid are reacted with N,N The molar concentration ratio of dimethylformamide is 15:5:15:

3.

7. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The reaction temperature of the high-pressure reactor is set at 120~140℃.

8. The method for preparing a photovoltaic-storage integrated catalyst according to claim 1, characterized in that, The high-pressure reactor is set to operate for 14-24 hours.

9. A catalyst suitable for integrated photovoltaic and energy storage, characterized in that, It is prepared by any one of the preparation methods of the integrated photovoltaic and energy storage catalyst according to any one of claims 1-8.

10. The application of a catalyst suitable for integrated photovoltaic and energy storage as described in claim 9 in the electrosynthesis of hydrogen peroxide, characterized in that, Silicon solar panels are used as photovoltaic modules in an integrated photovoltaic-energy storage system. These modules are connected to an electrolysis module to form a closed loop. The electrolysis module uses carbon paper loaded with a catalyst suitable for integrated photovoltaic-energy storage as the cathode, and uses Pt / C or other suitable catalysts as the cathode. The carbon paper is used as the anode, and electrolysis is carried out in an alkaline electrolyte to produce hydrogen peroxide.

Images