High-performance oxygen evolution reaction composite electrocatalyst and preparation method thereof

Abstract

The invention discloses a high-performance oxygen evolution reaction composite electrocatalyst and a preparation method thereof, belongs to the field of preparation of electrocatalytic materials, and solves the problem that the performance and repeatability of the prepared electrocatalyst are affected due to the fact that uniform loading and accurate size regulation and control of RuO2 nanoparticles are difficult to realize on a three-dimensional porous complex substrate (foamed nickel). The method comprises the following steps: firstly vulcanizing foamed nickel by using thiourea, and then uniformly depositing RuO2 nanoparticles on the surface of foamed nickel-based Ni3S2 by using an ALD (Atomic Layer Deposition) technology. The size of RuO2 nanoparticles on the surface of the foamed nickel-based Ni3S2 is accurately controlled to be 1.5-3.5 nm through the ALD technology, the surface density is controlled to be 0.8-1.21012 / cm < 2 >, the conductivity and electrochemical activity of the catalyst can be improved, the charge transfer rate can be improved, and the OER performance of the electrocatalyst is improved.

Description

Technical Field

[0001] The invention belongs to the field of preparation of electrocatalytic materials, and in particular relates to a high-performance oxygen evolution reaction composite electrocatalyst and a preparation method thereof. Background Art

[0002] As environmental problems caused by excessive use of fossil fuels become increasingly prominent, the development of clean, efficient and sustainable energy is urgent. Hydrogen energy is regarded as the cleanest energy with the greatest development potential in the 21st century, and water electrolysis is considered to be one of the most promising methods for large-scale production of high-purity hydrogen and oxygen. The oxygen evolution reaction on the anode in the water electrolysis reaction is a four-electron transfer process. Compared with the two-electron transfer hydrogen evolution reaction, a higher overpotential is required to overcome the kinetic barrier, which is a key factor restricting the efficiency of the entire water electrolysis reaction; therefore, exploring highly active OER catalysts has become one of the research hotspots.

[0003] Transition metal catalysts for efficient water splitting, such as oxides, phosphides, carbides, chalcogenides and selenides, have gradually replaced expensive iridium-based OER catalysts due to their excellent activity. Among them, nickel foam-based nickel sulfide (Ni3S2) has attracted more and more attention due to its advantages such as good conductivity and easy preparation. However, the binding strength of Ni3S2 with oxygen-containing intermediates is too strong, resulting in poor OER activity. In order to improve the performance of Ni3S2, it can be modified by loading suitable catalyst particles on its surface to increase the specific surface area and active sites to improve the electrochemical activity; studies have shown that RuO2 is not only a material with relatively good conductivity, but also has excellent OER activity. At present, there are methods for preparing RuO2 nanoparticles, mainly including hydrothermal method, thermal decomposition method, electrochemical deposition method, sol-gel method, etc., but the above traditional methods are still insufficient in accurately controlling the particle size and distribution, especially in achieving uniform particle deposition on the surface of three-dimensional porous complex substrates. Summary of the invention

[0004] The present invention provides a high-performance oxygen evolution reaction composite electrocatalyst and a preparation method thereof. In view of the problem that it is currently difficult to achieve uniform loading and precise control of the size of RuO2 nanoparticles on the surface of a three-dimensional porous complex substrate (nickel foam), which affects the performance and repeatability of the prepared electrocatalyst, the ALD method is used to uniformly deposit RuO2 nanoparticles on the surface of nickel foam-based Ni3S2 to obtain a stable, high-performance OER composite electrocatalyst.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A high-performance composite electrocatalyst for oxygen evolution reaction, which is a foam nickel-based Ni3S2 surface uniformly loaded with RuO2 nanoparticles; the size of the RuO2 nanoparticles is precisely controlled to be 1.5-3.5 nm, and the surface density is 0.8-1.2´1012 / cm 2 .

[0006] A method for preparing a high-performance oxygen evolution reaction composite electrocatalyst comprises the following steps: Step 1: Cut the nickel foam mesh and use it as a template after ultrasonic cleaning with ethanol and deionized water; Step 2: Place the cleaned nickel foam mesh in an HCl solution for ultrasonic treatment, then clean the surface of the mesh with ethanol and deionized water, and then dry it to obtain a clean nickel mesh; Step 3: Add thiourea and high-purity water into a stainless steel hydrothermal reactor, put the treated nickel foam mesh into it, and carry out a sulfidation reaction under heating conditions at a reaction temperature of 150°C for 5 hours. After the reaction is completed, take out the sample, wash it thoroughly with water and anhydrous ethanol, and dry it to obtain nickel foam-based Ni3S2; Step 4: ALD is used to grow RuO2 nanoparticles on nickel-based Ni3S2 foam, the precursor used is ethyl bis(dicyclopentadienyl)ruthenium, the source temperature is 65°C, and the reactant is oxygen, to obtain nickel-based Ni3S2 / RuO2 foam; The growth temperature of ALD growth of RuO2 is 200°C-350°C, the flow rate of oxygen is 100-200sccm, and the number of cycles is 150-250 cycles.

[0007] Beneficial effect: The present invention provides a high-performance composite electrocatalyst for oxygen evolution reaction and a preparation method thereof, wherein Ni3S2 is synthesized by sulfidation of nickel foam, and then RuO2 nanoparticles are uniformly deposited on the nickel foam-based Ni3S2 by ALD to obtain a nickel foam-based Ni3S2 / RuO2 composite electrocatalyst. The method of the present invention can precisely control the size and density of the RuO2 nanoparticle catalyst by changing the number of ALD cycles, with a particle size of 1.5-3.5 nm and a surface density of 0.8-1.2´10 12 / cm 2 , can achieve uniform loading and precise control of the size of RuO2 nanoparticles, optimize the interface between nickel foam-based Ni3S2 and RuO2 nanoparticles, and utilize Ni3S2 / RuO2 interface optimization to maximize the exposure of active sites, and the higher RuO2 surface density increases the number of active sites. The smaller RuO2 particle size helps to shorten the diffusion distance, promote the transmission of charge in RuO2 particles, improve the conductivity and electrochemical activity of the catalyst, and thus improve the electrocatalytic performance of OER. The process of the present invention is simple and controllable, and the prepared composite electrocatalyst has not only excellent OER performance, but also good stability, and can be applied to the field of energy catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the synthesis of the composite electrocatalyst in an embodiment of the present invention; Figure 2 The SEM photo (a) of the nickel-based Ni3S2 foam synthesized and prepared in the embodiment of the present invention and the TEM photo (b) of the RuO2 nanoparticles after 200 cycles; Figure 3 The linear sweep voltammetry curves of the composite electrocatalyst prepared in the embodiment of the present invention and its reference sample; Figure 4 is a Tafel slope curve diagram of the composite electrocatalyst prepared in the embodiment of the present invention and its reference sample; Figure 5 The cyclic voltammetry curves of the composite electrocatalyst prepared in the embodiment of the present invention and its reference sample, wherein (a) is the Ni3S2 / RuO2-200 cycle, (b) is Ni3S2, (c) is RuO2-200 cycle, and (d) is the current density difference of the three at different scan rates; Figure 6 Stability curves of (a) composite electrocatalyst and (b) Ni3S2 prepared in the examples of the present invention. DETAILED DESCRIPTION

[0009] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: Example 1

[0010] like Figure 1 As shown, a method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction comprises the following steps: 1) First, cut the nickel foam into 1 cm × 3 cm size and clean it in anhydrous ethanol and deionized water; 2) The cleaned nickel foam mesh was ultrasonicated in anhydrous ethanol and 3M HCl for 30 min respectively. After ultrasonication, it was rinsed with deionized water and ethanol several times to ensure thorough cleaning. After cleaning, it was placed in an oven at 80°C for drying; 3) Add 13 mL of water and 0.11 g of thiourea into the hydrothermal reactor and stir for 30 min to ensure that the thiourea is completely dissolved. Then put the pretreated nickel foam mesh into the hydrothermal reactor containing the thiourea aqueous solution. After the treatment, place the hydrothermal reactor at 150 °C for 5 h. After the heating is completed, take out the sulfurized nickel foam mesh, wash it with deionized water and anhydrous ethanol, and dry it to obtain nickel-based Ni3S2 foam. 4) RuO2 nanoparticles were grown on nickel-based Ni3S2 foam by ALD method. The specific growth conditions were as follows: growth temperature was 250°C; the precursor was ethylruthenocene, the source temperature was 65°C, and the reactant was oxygen; the deposition pulse cycles were 1 s ethylruthenocene pulse, 4 s cleaning pulse, 8 s O2 pulse, and 4 s cleaning pulse, and the cleaning gas and carrier gas were both high-purity nitrogen (N2, 99.999%); the oxygen flow rate was 150 sccm; the number of growth cycles was 200 cycles, and nickel-based Ni3S2 / RuO2 foam was obtained.

[0011] Example 2 like Figure 1 As shown, a method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction comprises the following steps: 1) First, cut the nickel foam into 1 cm × 3 cm size and clean it in anhydrous ethanol and deionized water; 2) The cleaned nickel foam mesh was ultrasonicated in anhydrous ethanol and 3M HCl for 30 min respectively, and then rinsed with deionized water and ethanol several times to ensure thorough cleaning. After cleaning, it was placed in an oven at 80°C for drying; 3) Add 13 mL of water and 0.11 g of thiourea to the hydrothermal reactor and stir for 30 min to ensure that the thiourea is completely dissolved. Then put the pretreated nickel foam mesh into the hydrothermal reactor containing the thiourea aqueous solution. After the treatment, place the hydrothermal reactor at 150 °C for 5 h. After the heating is completed, take out the sulfurized nickel foam mesh, wash it with deionized water and anhydrous ethanol, and dry it to obtain nickel-based Ni3S2 foam; 4) RuO2 nanoparticles were grown on nickel-based Ni3S2 foam by ALD method. The specific growth conditions were as follows: growth temperature was 200°C; the precursor was ethylruthenocene, the source temperature was 65°C, and the reactant was oxygen; the deposition pulse cycles were 1 s ethylruthenocene pulse, 4 s cleaning pulse, 8 s O2 pulse, and 4 s cleaning pulse, and the cleaning gas and carrier gas were both high-purity nitrogen (N2, 99.999%); the oxygen flow rate was 100 sccm; the number of growth cycles was 250 cycles; and nickel-based Ni3S2 / RuO2 foam was obtained.

[0012] Example 3 like Figure 1 As shown, a method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction comprises the following steps: 1) First, cut the nickel foam into 1 cm × 3 cm size and clean it in anhydrous ethanol and deionized water; 2) The cleaned nickel foam mesh was ultrasonicated in anhydrous ethanol and 3M HCl for 30 min respectively, and then rinsed with deionized water and ethanol several times to ensure thorough cleaning. After cleaning, it was placed in an oven at 80°C for drying; 3) Add 13 mL of water and 0.11 g of thiourea to the hydrothermal reactor and stir for 30 min to ensure that the thiourea is completely dissolved. Then put the pretreated nickel foam mesh into the hydrothermal reactor containing the thiourea aqueous solution. After the treatment, place the hydrothermal reactor at 150 °C for 5 h. After the heating is completed, take out the sulfurized nickel foam mesh, wash it with deionized water and anhydrous ethanol, and dry it to obtain nickel-based Ni3S2 foam; 4) RuO2 nanoparticles were grown on nickel-based Ni3S2 foam by ALD method. The specific growth conditions were as follows: growth temperature was 300℃; the precursor was ethylruthenocene, the source temperature was 65℃, and the reactant was oxygen; the deposition pulse cycles were 1 s ethylruthenocene pulse, 4 s cleaning pulse, 8 s O2 pulse, 4 s cleaning pulse, and the cleaning gas and carrier gas were both high-purity nitrogen (N2, 99.999%); the oxygen flow rate was 200 sccm; the number of growth cycles was 150 cycles; and nickel-based Ni3S2 / RuO2 foam was obtained.

[0013] like Figure 2 As shown, the Ni3S2 obtained in the above embodiment is in the form of nanosheets, and the obtained composite catalyst is a Ni3S2 surface uniformly loaded with 200 cycles of RuO2 nanoparticles, the average particle size of which is only 2.6 nm, and the surface density is 1.2´10 12 / cm 2 .

[0014] The composite electrocatalyst prepared in Example 1 was used as a working electrode, and a graphite electrode and Hg / HgO were used as a counter electrode and a reference electrode, respectively, to form a three-electrode system. The electrochemical performance of the foamed nickel-based Ni3S2 / RuO2-200 circulating sample and the reference sample foamed nickel-based Ni3S2 and RuO2-200 circulating catalyst were tested using an electrochemical workstation at room temperature with a KOH solution saturated with oxygen at a concentration of 1 mol / L as an electrolyte solution. The test results are shown in FIG. Figure 3 As shown, at 10mA / cm 2 At a current density of , the overpotentials of the nickel foam-based Ni3S2 / RuO2-200 cycle, nickel foam-based Ni3S2 and RuO2-200 cycle are 1.37mV, 1.62mV and 1.59mV respectively. Figure 4It can be seen that the Tafel slopes of the above three samples are 59 mV / dec, 200 mV / dec, and 134 mV / dec, respectively. The foam nickel-based Ni3S2 / RuO2-200 cycle sample shows the best Tafel slope, proving that the prepared electrocatalyst has a high OER catalytic activity. Figure 5 In the cyclic voltammetry curve of the nickel foam-based Ni3S2 / RuO2-200 cycle sample, the cyclic voltammetry curve of the nickel foam-based Ni3S2 / RuO2-200 cycle sample has a value of 51.36 mF / cm 2 The double-layer capacitance further illustrates that the composite electrocatalyst prepared by the above method can provide more charge storage sites and promote charge transfer. Figure 6 The cyclic stability test curve of the nickel foam-based Ni3S2 / RuO2-200 cyclic sample shows that the nickel foam-based Ni3S2 / RuO2-200 cyclic sample has good stability compared with Ni3S2, indicating that the present invention uses ALD technology to grow uniformly loaded RuO2 nanoparticles on the nickel foam-based Ni3S2, thereby improving the corrosion resistance of the electrocatalyst.

[0015] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction, characterized in that: The following steps are involved: Preparation of three-dimensional porous complex substrates; The composite electrocatalyst is obtained by uniformly depositing RuO2 nanoparticles on a three-dimensional porous complex substrate using ALD technology.

2. The method for preparing a high-performance oxygen evolution reaction composite electrocatalyst according to claim 1, characterized in that: The precursor used in ALD is ethylruthenocene and the reactant is oxygen.

3. The method for preparing a high-performance oxygen evolution reaction composite electrocatalyst according to claim 1 or 2, characterized in that: The source temperature in ALD was 65 °C.

4. The method for preparing a high-performance oxygen evolution reaction composite electrocatalyst according to claim 1 or 2, characterized in that: The growth temperature of RuO2 deposited by ALD technology is 200℃-350℃.

5. The method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction according to claim 2, characterized in that: The flow rate of oxygen is 100-200 sccm.

6. The method for preparing a high-performance oxygen evolution reaction composite electrocatalyst according to claim 4, characterized in that: The number of cycles was 150-250 cycles.

7. The method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction according to claim 1 or 4, characterized in that: The ALD deposition pulse cycle is 1s ethylruthenocene pulse, 4s cleaning pulse, 8s O2 pulse, and 4s cleaning pulse.

8. The method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction according to claim 1, characterized in that: The three-dimensional porous complex substrate is foamed nickel-based Ni3S2.

9. The method for preparing a high-performance composite electrocatalyst for oxygen evolution reaction according to claim 8, characterized in that: The preparation method of the nickel-based Ni3S2 foam comprises the following steps: Step 1: Cut the nickel foam mesh and use it as a template after ultrasonic cleaning with ethanol and deionized water; Step 2: Place the cleaned nickel foam mesh in an HCl solution for ultrasonic treatment, then clean the surface of the mesh with ethanol and deionized water, and then dry it to obtain a clean nickel mesh; Step 3: Add thiourea and high-purity water into a stainless steel hydrothermal reactor, put the treated nickel foam mesh into it, and carry out sulfidation reaction under heating conditions. The reaction temperature is 150°C and the time is 5 hours. After the reaction is completed, take out the sample, wash it thoroughly with water and anhydrous ethanol, and dry it to obtain nickel foam-based Ni3S2.

10. A high-performance oxygen evolution reaction composite electrocatalyst prepared by the method according to any one of claims 1 to 9, characterized in that: The composite catalyst is a three-dimensional porous complex substrate surface uniformly loaded with RuO2 nanoparticles, the RuO2 nanoparticle size is controlled at 1.5-3.5 nm, the surface density is 0.8-1.2*10 12 / cm 2 .

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