A binary metal nanoparticle biochar composite nanocatalyst for efficient hydrogen production by water electrolysis and a preparation method thereof

Abstract

The application discloses a kind of binary metal nanoparticle biochar composite nanocatalyst of high-efficiency water electrolysis hydrogen production and preparation method thereof.The application obtains new high-performance water electrolysis hydrogen evolution catalyst by using bimetallic nanoparticles to modify biomass carbon material, and the synergistic effect of two kinds of metal is used to improve the performance of catalyst, and the binary metal nanoparticle / biochar composite catalyst prepared is in-situ anchored on the surface of N-doped biochar, uniformly distributed, the grain size is adjustable in 2nm-10nm, the water electrolysis hydrogen evolution catalytic activity is high, and the stability is good, and the overpotential is 29.7mV under 10mA / cm 2 Current density, and can still maintain 99.4% after 1000 cycles, and has wide application prospect in the fields of electrochemistry, energy and environment.The raw material preparation, mixing precursor impregnation and heat treatment process of the application do not cause water pollution, air pollution and other problems, and the preparation method is green, simple, convenient and low in preparation cost.

Description

Technical Field

[0001] This invention belongs to the field of energy catalytic conversion technology, and particularly relates to a platinum-palladium bimetallic nanoparticle biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen and its preparation method. Background Technology

[0002] Electrolysis of water is a crucial method for hydrogen production, and catalysts play a key role in this process. Traditional catalysts typically use single-metal-based materials, whose performance is limited by the inherent properties of the metal. Bimetallic catalysts, however, exhibit superior performance compared to single-metal catalysts due to the synergistic effect between the two metals. Furthermore, biomass materials are inexpensive and readily available; carbon materials obtained through pyrolysis possess abundant porosity and high specific surface area, exhibiting high electronic conductivity and good chemical stability, providing numerous and stable catalyst sites, making them excellent catalyst supports. However, traditional catalyst preparation methods often suffer from complex processes, stringent reaction conditions, and low product purity. Therefore, developing a simple, easily controllable, environmentally friendly, and economical preparation method is of great research value. Summary of the Invention

[0003] To address the aforementioned issues and overcome the limitations in performance improvement of existing single-metal-based catalysts and the complexity of bimetallic catalyst preparation processes, this invention synthesizes a binary metal nanoparticle / biochar composite catalyst. This catalyst allows the binary metal to be in situ anchored on the surface of N-doped biochar material. Through the synergistic effect of the two metals, the performance improvement of single-metal-based catalysts is overcome by the inherent characteristics of the single metal itself. The process is simple and convenient, the resulting binary metal nanoparticles are uniformly distributed on the N-doped biochar material support, the particle size is controllable, and it exhibits high catalytic activity and good stability in water electrolysis and hydrogen evolution.

[0004] To achieve the above objectives, the following technical solution is adopted: This invention provides a binary metal nanoparticle-biochar composite nanocatalyst for efficient water electrolysis to produce hydrogen, the preparation method comprising the following steps: (1) Prepare 20 mL of a binary metal compound aqueous solution with a total metal ion concentration of 0.01 mol / L, immerse 10 g of biomass material in the binary metal compound aqueous solution, then take it out and place it in a freeze dryer for freezing and drying to obtain binary metal-biochar precursor material; (2) The binary metal-biochar precursor material is loaded into a corundum crucible and heat-treated in a tube furnace with a certain protective atmosphere. After being taken out, it is ground to obtain a binary metal nanoparticle biochar composite nanocatalyst.

[0005] Furthermore, the binary metal compound aqueous solution is selected as an immiscible Pt-Ce, Pt-Pd, or Pt-Cu system, and the metal compound raw material of the binary metal compound aqueous solution is a combination of one of palladium chloroacetic acid and palladium acetylacetonate and one of chloroplatinic acid, cerium chloride hexahydrate, copper chloride dihydrate, or copper nitrate trihydrate.

[0006] Furthermore, the biomass material is linden wood veneer.

[0007] Furthermore, the biomass material is pretreated as follows: soaked in deionized water for 2 hours, with the water changed every half hour.

[0008] Furthermore, the immersion time in step (1) of the preparation method is 4 hours.

[0009] Furthermore, the freezing time in step (1) of the preparation method is 24 hours, the freezing temperature is -40°C to -60°C, the drying vacuum degree in step (1) of the preparation method is 1 Pa, and the drying time is 48 hours.

[0010] Furthermore, the protective atmosphere is either argon or nitrogen.

[0011] Furthermore, the heat treatment time for step (2) of the preparation method is 4 hours.

[0012] Furthermore, the heat treatment temperature is 600℃-1100℃.

[0013] Furthermore, the heating rate of the heat treatment is 10°C / min.

[0014] The beneficial effects of this invention are: (1) This invention uses bimetallic nanoparticles to modify biochar materials to obtain a novel high-performance hydrogen evolution catalyst for water electrolysis. The synergistic effect of the two metals improves the catalyst performance. In the prepared binary metal nanoparticle / biochar composite catalyst, the metal nanoparticles are in situ anchored on the surface of N-doped biochar, with uniform distribution and small grain size. The catalytic activity for hydrogen evolution in water electrolysis is adjustable from 2nm to 10nm, with high activity and good stability. It has an overpotential of 29.7mV at a current density of 10mA / cm2 and can still maintain 99.4% after 1000 cycles. It has broad application prospects in electrochemistry, energy and environment. (2) The raw material preparation, mixing precursor impregnation and heat treatment process of the present invention will not generate water pollution, air pollution and other problems. The preparation method is green and environmentally friendly, simple in process, convenient to operate and low in preparation cost. Attached Figure Description

[0015] Figure 1A transmission electron microscope image of the PtPd / biochar composite catalyst provided in Example 1 of this invention; Figure 2 The X-ray diffraction pattern of the PtPd / biochar composite catalyst provided in Example 1 of this invention; Figure 3 The hydrogen evolution polarization curve of the PtPd / biochar composite catalyst provided in Example 1 of this invention; Figure 4 The hydrogen evolution polarization curves of the PtPd / biochar composite catalyst provided in Example 1 of this invention before and after 1000 cycles; Figure 5 Transmission electron microscope image and particle size distribution diagram of the PtCe / biochar composite catalyst provided in Example 2 of the present invention; Figure 6 This is a particle size distribution diagram of the PtCe / biochar composite catalyst provided in Example 2 of the present invention.

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0019] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels. Example 1

[0020] A method for preparing a PtPd / biochar composite catalyst The preparation method includes the following steps: (1) Prepare 20 mL of a mixed aqueous solution of chloroplatinic acid and chloropalladium acid with a total metal ion concentration of 0.01 mol / L (of which chloroplatinic acid is 0.008 mol / L and chloropalladium acid is 0.002 mol / L). After stirring thoroughly, a yellow clear solution is formed. Immerse 10 g of linden wood chips (thickness of 2.5 ± 1 mm, obtained after pretreatment by soaking in deionized water for 2 h) in the yellow clear solution for 4 h. (2) After impregnation, the material is taken out and placed in a freeze dryer for freeze drying. The freezing time is 24 hours, the freezing temperature is -40℃ to -60℃, the drying vacuum degree is 1 Pa, and the drying time is 48 hours. The bulk material obtained after freeze drying is the PtPd / biochar precursor material. Then, the PtPd / biochar precursor material is loaded into a crucible as raw material and heat-treated in a tube furnace under Ar protective atmosphere. The temperature is raised to 1000℃ at a heating rate of 10℃ / min and held at this temperature for 2 hours. After natural cooling to room temperature, the obtained solid is ground. The ground powder is the PtPd / biochar composite catalyst. Example 2

[0021] A method for preparing a PtCe / biochar composite catalyst The preparation method includes the following steps: (1) Prepare 20 mL of a mixed aqueous solution of chloroplatinic acid and cerium chloride hexahydrate with a total metal ion concentration of 0.01 mol / L (of which chloroplatinic acid is 0.075 mol / L and cerium chloride hexahydrate is 0.025 mol / L). After stirring thoroughly, a yellow clear solution is formed. Immerse 10 g of linden wood chips (thickness of 2.5 ± 1 mm, obtained after pretreatment by soaking in deionized water for 2 h) in the yellow clear solution for 4 h. (2) After impregnation, the material is taken out and placed in a freeze dryer for freeze drying. The freezing time is 24 hours, the freezing temperature is -40℃ to -60℃, the drying vacuum degree is 1 Pa, and the drying time is 48 hours. The bulk material obtained after freeze drying is the PtCe / biochar precursor material. Then, the PtCe / biochar precursor material is loaded into a crucible as raw material and heat-treated in a tube furnace under Ar protective atmosphere. The temperature is raised to 1000℃ at a heating rate of 10℃ / min and held at this temperature for 2 hours. After natural cooling to room temperature, the obtained solid is ground. The ground powder is the PtCe / biochar composite catalyst. Example 3

[0022] A method for preparing a PtCu / biochar composite catalyst The preparation method includes the following steps: (1) Prepare 20 mL of a mixed aqueous solution of chloroplatinic acid and copper chloride dihydrate with a total metal ion concentration of 0.01 mol / L (of which chloroplatinic acid is 0.0067 mol / L and copper chloride dihydrate is 0.0033 mol / L). After stirring thoroughly, a yellow clear solution is formed. Immerse 10 g of linden wood chips (thickness of 2.5 ± 1 mm, obtained by pretreatment by soaking in deionized water for 2 h) in the yellow clear solution for 4 h. (2) After impregnation, the material is taken out and placed in a freeze dryer for freeze drying. The freezing time is 24 hours, the freezing temperature is -40℃ to -60℃, the drying vacuum degree is 1 Pa, and the drying time is 48 hours. The bulk material obtained after freeze drying is the PtCu / biochar precursor material. Then, the PtCu / biochar precursor material is loaded into a crucible as raw material and heat-treated in a tube furnace under Ar protective atmosphere. The temperature is raised to 1100℃ at a heating rate of 10℃ / min and held at this temperature for 2 hours. After natural cooling to room temperature, the obtained solid is ground. The ground powder is the PtCu / biochar composite catalyst.

[0023] Results Analysis The PtPd / biochar composite catalyst prepared in Example 1 was characterized by TEM and XRD. The TEM results of the obtained samples are as follows: Figure 1 As shown, metal nanoparticles are uniformly loaded on biochar with an average particle size of 6.26 nm. The XRD results are as follows. Figure 2 As shown, characteristic diffraction peaks of Pt, Pd, and PtPd alloys are present.

[0024] The PtPd / biochar composite catalyst prepared in Example 1 was tested for its catalytic performance in water electrolysis and hydrogen evolution in a three-electrode system. The specific method is as follows: a graphite carbon electrode was used as the counter electrode, a silver chloride electrode containing saturated potassium chloride solution was used as the reference electrode, and a glassy carbon electrode supported on the PtPd / biochar composite catalyst was used as the working electrode. The electrolyte was a 0.5 mol / L acidic H₂SO₄ solution, and the scan rate was 100 mV / s. The test results are as follows: Figure 3 As shown, when the current density is 10 mA / cm2, the PtPd / biochar composite catalyst prepared in this example exhibits excellent electrocatalytic hydrogen evolution performance, with an overpotential of 29.7 mV.

[0025] The PtCe / biochar composite catalyst prepared in Example 2 was characterized by TEM, such as... Figure 5 As shown, metal nanoparticles The particles are uniformly loaded onto the biochar, and their average particle size is as follows: Figure 6 As shown, the wavelength is 5.18nm ± 1.26nm.

[0026] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0027] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a platinum-palladium bimetallic nanoparticle biochar composite nanocatalyst for efficient hydrogen production by water electrolysis, characterized by: The preparation method includes the following steps: (1) Prepare 20 mL of a platinum-palladium bimetallic compound aqueous solution with a total metal ion concentration of 0.01 mol / L. Immerse 10 g of biomass material in the platinum-palladium bimetallic compound aqueous solution, then remove it and place it in a freeze dryer for freezing and drying to obtain platinum-palladium bimetallic-biochar precursor material. The biomass material is linden wood chips. The biomass material is pretreated as follows: soaked in deionized water for 2 h, with the water changed every half hour. (2) The platinum-palladium bimetallic-biochar precursor material is loaded into a corundum crucible and heat-treated in a tube furnace with a protective atmosphere. After being taken out, it is ground to obtain a platinum-palladium bimetallic nanoparticle biochar composite nanocatalyst.

2. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 1, characterized in that: In the aqueous solution of the metal compound, the raw material of the metal compound is one of chloropalladium acid, palladium acetylacetonate, and chloroplatinic acid.

3. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 2, characterized in that: The soaking time in step (1) of the preparation method is 4 hours.

4. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 3, characterized in that: The freezing time in step (1) of the preparation method is 24 hours, and the freezing temperature is -40°C to -60°C; the drying vacuum degree in step (1) of the preparation method is 1 Pa, and the drying time is 48 hours.

5. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 4, characterized in that: The protective atmosphere is either argon or nitrogen.

6. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 5, characterized in that: The heat treatment time for step (2) of the preparation method is 4 hours.

7. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 6, characterized in that: The heat treatment temperature is 600℃-1100℃.

8. The method for preparing a platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for high-efficiency water electrolysis to produce hydrogen according to claim 7, characterized in that: The heating rate for the heat treatment is 10℃ / min.

9. A highly efficient platinum-palladium bimetallic nanoparticle-biochar composite nanocatalyst for hydrogen production via water electrolysis, characterized in that: The composite nanocatalyst prepared according to the preparation method described in claim 8.

Images