Preparation methods and applications of RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalysts

Abstract

This invention belongs to the field of electrocatalysis preparation and application, specifically relating to the preparation method and application of a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. The invention synthesizes a CeO2 / C precursor on a carbon sphere template, obtains CeO2 hollow carbon spheres through thermal calcination, then loads RuSe2 onto the CeO2 hollow carbon spheres via a hydrothermal method to obtain fresh RuSe2 / CeO2 hollow carbon spheres, and finally calcines them to obtain the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. The interfacial interaction between RuSe2 and CeO2 facilitates rapid surface charge transfer, thereby enhancing the electrochemical performance of the catalyst. Due to the synergistic effect of this heterostructure, it exhibits excellent hydrogen evolution capacity in an alkaline environment. The synthesized RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst has the advantages of an environmentally friendly and simple synthesis process and excellent electrocatalytic water splitting and hydrogen evolution performance.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst preparation and application, specifically relating to the preparation of a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst and its application in hydrogen evolution through electrocatalytic water splitting. Technical Background

[0002] Platinum (Pt) is currently known as the best catalyst for hydrogen evolution reaction (HER) from water, but its application is limited due to its scarcity and high cost. As an alternative, ruthenium (Ru) is much cheaper than Pt, can bond with hydrogen, and the Ru-H bond strength is similar to that of the Pt-H bond. In particular, Ru exhibits excellent chemical performance in water dissociation and OH- chemisorption, and possesses inherent HER activity, making Ru-based catalysts promising for HER applications. Furthermore, due to the flexible coordination mode and low ionization energy of selenium, Se coordinates with transition metal Ru, forming a Se-Ru bond with a negative charge, which promotes proton adsorption and thus HER. This selenium-modified metal catalyst exhibits good corrosion resistance and electronic conductivity in the electrolyte. For transition metal selenide catalysts for HER, both metal atoms and selenium atoms can serve as active sites for hydrogen adsorption, especially in selenium-rich catalysts. Therefore, RuSe2 can be used as a highly efficient electrocatalyst for electrochemical water splitting to produce hydrogen.

[0003] Cerium oxide (CeO2) possesses high electronic / ionic conductivity, high redox potential, and abundant oxygen vacancies. This is attributed to its abundant half-filled and empty d orbitals and the presence of CeO2. 3+ To Ce 4+ The flexible transformation of CeO2 allows for oxygen ion exchange, generating oxygen vacancies. Furthermore, CeO2 is an activator that enhances catalytic performance due to its multivalent nature, enabling electron transfer between heterostructure interfaces; it also increases surface area, enriches surface defects, and optimizes the surface active sites of the catalyst. Although pure CeO2 exhibits relatively poor hydrogen evolution activity, its synergistic effect with other catalytic materials significantly improves this activity. Therefore, the RuSe2 / CeO2 heterostructure interface introduced in this invention modulates the electronic structure, accelerates charge transfer, and enhances the intrinsic activity of the active sites. Summary of the Invention

[0004] The purpose of this invention is to provide a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst and its preparation method, and to apply the electrocatalyst to the electrocatalytic splitting of water in an alkaline electrolyte to produce hydrogen, which exhibits excellent hydrogen evolution performance.

[0005] The technical solution of this invention: This invention provides a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. The preparation method of this catalyst is as follows: First, a carbon sphere template is synthesized by hydrothermal method. Then, a CeO2 / C precursor is synthesized on the carbon sphere template. Subsequently, CeO2 hollow carbon spheres are obtained by heat treatment in a tube furnace in N2 atmosphere and air atmosphere. Then, RuSe2 is loaded on the CeO2 hollow carbon spheres by hydrothermal method to obtain fresh RuSe2 / CeO2 hollow carbon spheres. Finally, RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst is obtained by heat treatment in a tube furnace in N2 atmosphere.

[0006] The specific process is as follows:

[0007] (1) Dissolve glucose in deionized water and stir until dissolved. Transfer the solution to a polytetrafluoroethylene-sealed autoclave and then place it in a drying oven to react. Keep it at 180°C for 5 hours. After the reaction is completed and the product is cooled naturally, take out the product and wash it with deionized water by centrifugation until the supernatant becomes transparent. Then place it in a vacuum drying oven and dry it under vacuum at 60°C to obtain carbon ball template.

[0008] (2) The carbon sphere template, cerium nitrate hexahydrate, and urea were dissolved in deionized water and sonicated until homogeneous. The solution was then transferred to a polytetrafluoroethylene-sealed autoclave and placed in a forced-air drying oven for reaction at 120°C for 12 hours. After the reaction was completed and the mixture was allowed to cool naturally, the product was removed and washed with deionized water by centrifugation until the supernatant became transparent. The supernatant was then dried in a vacuum drying oven at 60°C to obtain the CeO2 / C precursor. The CeO2 / C precursor was calcined in a tube furnace under N2 atmosphere for 2 hours, and then calcined in a tube furnace under air atmosphere for 2 hours to obtain CeO2 hollow carbon spheres.

[0009] The molar ratio of carbon spheres, cerium nitrate hexahydrate, and urea was 4:2:5. The calcination temperature was 400℃, and the heating rate was 5℃ / min.

[0010] (3) CeO2 hollow carbon spheres and Se powder were dispersed in deionized water and ultrasonically dispersed evenly. Then, a certain amount of RuCl3·xH2O and hydrazine hydrate were added to the above solution in sequence and stirred to make the solution evenly mixed. The solution was transferred to a polytetrafluoroethylene sealed high-pressure reactor and then placed in a forced-air drying oven for reaction. After the reaction was completed and naturally cooled, the product was taken out and washed with deionized water and ethanol in sequence by centrifugation until the supernatant became transparent. It was kept at 120°C for 12 hours and then placed in a vacuum drying oven at 60°C to dry under vacuum to obtain fresh RuSe2 / CeO2 hollow carbon spheres.

[0011] (4) Fresh RuSe2 / CeO2 hollow carbon spheres were placed in a tube furnace under N2 atmosphere and calcined at 200℃~600℃ for 2h at a heating rate of 5℃ / min to obtain the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. The molar ratio of Se powder to RuCl3 was 2:1. The mass ratio of RuSe2 in RuSe2 / CeO2 was 10%~60%.

[0012] Preferably, the mass ratio of RuSe2 in RuSe2 / CeO2 is 40%–60%; the most preferred mass ratio is 50%, and the calcination temperature is 400℃. The purpose of calcination is to enhance the crystallinity of RuSe2.

[0013] This invention synthesizes a carbon sphere template via a hydrothermal method, then synthesizes a CeO2 / C precursor on the template, followed by calcination in a tube furnace under N2 and air atmospheres to obtain hollow CeO2 carbon spheres. Next, RuSe2 is loaded onto the hollow CeO2 carbon spheres via a hydrothermal method to obtain fresh RuSe2 / CeO2 hollow carbon spheres. Finally, calcination in a tube furnace under N2 atmosphere yields a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. This invention optimizes the RuSe2 / CeO2 ratio to obtain a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst with optimal electrocatalytic water splitting performance.

[0014] This invention also provides a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst as a working electrode for the electrocatalytic splitting of water to produce hydrogen in an alkaline electrolyte.

[0015] This invention also provides a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst for electrocatalytic hydrogen evolution performance. The test method uses a standard three-electrode system, with the working electrode being a RuSe2 / CeO2 electrode, the counter electrode being a graphite rod electrode, and the reference electrode being a Hg / HgO electrode. The electrolyte is a 1 mol / L KOH solution.

[0016] The technical effects achieved by this invention are:

[0017] (1) The RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst provided by the present invention is prepared by hydrothermal method and heat treatment. The synthesis method is simple to operate and the product has a uniform phase.

[0018] (2) The RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst provided by the present invention has a spherical structure, which provides abundant diffusion channels for hydrogen bubbles and electrolytes, and promotes the hydrogen evolution reaction.

[0019] (3) The RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst provided by this invention exhibits excellent hydrogen evolution performance in an alkaline electrolyte of 1 mol / L KOH. At -10 mA / cm² 2 It exhibits a hydrogen evolution overpotential of -17mV at a given current density. Attached Figure Description

[0020] Figure 1 The XRD patterns of Example 1 and Comparative Examples 1-2 are shown.

[0021] Figure 2 This is the SEM image of Example 1.

[0022] Figure 3 The LSV polarization curves for hydrogen evolution are shown for Examples 1-5 and Comparative Examples 1-3.

[0023] Figure 4 The LSV polarization curve of hydrogen evolution is shown in Comparative Example 4.

[0024] Figure 5 The image shows the LSV polarization curves before and after 3000 CV cycles in Example 1.

[0025] Figure 6 This is a hydrogen evolution stability graph for Example 1.

[0026] Figure 7 The fine XPS spectra of Ru in Example 1 and Comparative Example 1 are shown. Detailed Implementation

[0027] The technical features of the present invention are further illustrated by the following examples, but the scope of protection of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] Preparation of 1.1 mol / L KOH solution

[0030] Dissolve 28g KOH in 500mL of ultrapure water, stir until the KOH is completely dissolved, and cool to room temperature. Then transfer the solution to a 500mL volumetric flask and make up to volume to obtain a 1mol / L KOH solution.

[0031] 2. Preparation of carbon sphere templates

[0032] Dissolve 6.3g of glucose in 70mL of deionized water and stir until homogeneous. Transfer the solution to an 80mL polytetrafluoroethylene-sealed autoclave and place it in a forced-air drying oven to react at 180℃ for 5 hours. After the reaction is complete and the mixture is allowed to cool naturally, remove the product and wash it with deionized water by centrifugation until the supernatant becomes transparent. Then place it in a vacuum drying oven at 60℃ to dry under vacuum to obtain carbon sphere templates.

[0033] 3. Preparation of CeO2 hollow carbon spheres

[0034] 4 mmol of carbon sphere template and 2 mmol of cerium nitrate hexahydrate were dissolved in 40 mL of deionized water and sonicated for 10 min to ensure homogeneity. Then, 5 mmol of urea was added and sonicated for 20 min to ensure homogeneity. The solution was transferred to an 80 mL polytetrafluoroethylene-sealed autoclave and placed in a forced-air drying oven for reaction at 120 °C for 12 h. After the reaction was completed and the mixture was allowed to cool naturally, the product was removed and washed with deionized water by centrifugation until the supernatant became transparent. The supernatant was then dried under vacuum at 60 °C to obtain the CeO2 / C precursor. The CeO2 / C precursor was then placed in tube furnaces under nitrogen and air atmospheres, and heated to 400 °C at a rate of 5 °C / min. It was then calcined at 400 °C for 2 h and then cooled to room temperature at a rate of 5 °C / min. After the reaction was completed, hollow CeO2 carbon spheres were obtained.

[0035] 4. Preparation of RuSe2 / CeO2 hollow carbon spheres

[0036] 25.8 mg of CeO2 hollow carbon spheres and 15.8 mg of Se powder were dispersed in 35 mL of deionized water and sonicated for 30 min to ensure uniform dispersion. Then, 20.65 mg of RuCl3·xH2O was added and stirred for 20 min. After that, 2 mL of hydrazine hydrate was added and stirred for 10 min to ensure uniform mixing. The solution was then transferred to an 80 mL polytetrafluoroethylene-sealed autoclave and placed in a forced-air drying oven for reaction at 120 °C for 12 h. After the reaction was completed and the mixture was allowed to cool naturally, the product was removed and washed sequentially with deionized water and ethanol by centrifugation until the supernatant became transparent. The product was then placed in a vacuum drying oven and dried under vacuum at 60 °C to obtain fresh RuSe2 / CeO2 hollow carbon spheres. Fresh RuSe2 / CeO2 hollow carbon spheres were placed in a tube furnace under N2 atmosphere and heated to 400°C at a heating rate of 5°C / min. The mixture was then calcined at 400°C for 2 hours and then cooled to room temperature at a cooling rate of 5°C / min. After the reaction was completed, a RuSe2 / CeO2 hollow carbon sphere (RuSe2 in RuSe2 / CeO2 mass ratio of 50%) heterostructure electrocatalyst was obtained.

[0037] application

[0038] 1. Activation treatment of electrocatalysts

[0039] (1) The electrochemical hydrogen evolution reaction uses a standard three-electrode system, with the working electrode having an area of ​​0.07 cm². 2 The RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst electrode has a graphite rod electrode as the counter electrode and a Hg / HgO electrode as the reference electrode, and the electrolyte is 1 mol / L KOH.

[0040] (2) Cyclic voltammetry (CV) activation: Jiangsu Donghua DH7000 electrochemical workstation was used with CV program, HER test range of -0.6 to -1.4 V vs. Hg / HgO, scan rate of 100 mV / s, 10 cycles, the electrode reached stable state after the program was completed.

[0041] 2. Linear sweep voltammetry (LSV) test

[0042] A linear sweep voltammetry procedure was used, with the HER test range being -0.6 to -1.4 V vs. Hg / HgO, and a scan rate of 5 mV / s. The electrocatalyst was tested in a 1 mol / L KOH alkaline electrolyte at a current density of -10 mA / cm². 2 At that time, the hydrogen evolution overpotential of the electrocatalyst prepared in Example 1 was -17mV.

[0043] 3. Stability Test

[0044] The timing potentiometric method was used, with the current set to -10mA and the time set to 72000s.

[0045] from Figure 1 The XRD pattern shows that the RuSe2 / CeO2 heterostructure catalyst prepared in Example 1 is composed of RuSe2 and CeO2 phases and does not contain other impurities, which indicates that the RuSe2 / CeO2 heterostructure catalyst was successfully prepared.

[0046] from Figure 2 SEM images show the spherical structure encapsulated by RuSe2 / CeO2 heterostructure nanoparticles.

[0047] from Figure 3 Examples 1-5 and Comparative Examples 1-3 and Figure 4 The hydrogen evolution LSV polarization curves of Comparative Example 4 show that the RuSe2 / CeO2 heterostructure catalyst prepared in Example 1 exhibits excellent alkaline hydrogen evolution, and the alkaline hydrogen evolution of the RuSe2 / CeO2 heterostructure catalyst calcined at 400°C is superior to that at other temperatures.

[0048] from Figure 5 LSV polarization curves before and after 3000 CV cycles and Figure 6 The hydrogen evolution stability diagram shows that the prepared RuSe2 / CeO2 heterostructure catalyst has good alkaline hydrogen evolution stability.

[0049] from Figure 7 The fine XPS spectra of Ru show that, compared to RuSe2, the Ru in the RuSe2 / CeO2 heterostructure catalyst is significantly higher. 4+ 3P3 / 2 and 3P 1 / 2 The orbitals all showed negative shifts, indicating that the heterostructure interface caused a redistribution of electrons, and also demonstrating the successful preparation of the RuSe2 / CeO2 heterostructure catalyst.

[0050] Example 2

[0051] The difference from Example 1 lies in the preparation of RuSe2 / CeO2 hollow carbon spheres. 232 mg of CeO2 hollow carbon spheres and 15.8 mg of Se powder were dissolved in 35 mL of deionized water.

[0052] The application method is the same as in Example 1. The RuSe2 / CeO2 hollow carbon sphere (10%) heterostructure electrocatalyst prepared in Example 2 was used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -136mV.

[0053] Example 3

[0054] The difference from Example 1 lies in the preparation of RuSe2 / CeO2 hollow carbon spheres. 103.1 mg of CeO2 hollow carbon spheres and 15.8 mg of Se powder were dissolved in 35 mL of deionized water.

[0055] The application method is the same as in Example 1. The RuSe2 / CeO2 hollow carbon sphere (20%) heterostructure electrocatalyst prepared in Example 3 was used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -89mV.

[0056] Example 4

[0057] The difference from Example 1 lies in the preparation of RuSe2 / CeO2 hollow carbon spheres. 34.4 mg of CeO2 hollow carbon spheres and 15.8 mg of Se powder were dissolved in 35 mL of deionized water.

[0058] The RuSe2 / CeO2 hollow carbon sphere (40%) heterostructure electrocatalyst prepared in Example 1 and Example 4 was used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -57mV.

[0059] Example 5

[0060] The difference from Example 1 lies in the preparation of RuSe2 / CeO2 hollow carbon spheres. 17.2 mg of CeO2 hollow carbon spheres and 15.8 mg of Se powder were dissolved in 35 mL of deionized water.

[0061] The application method is the same as in Example 1. The RuSe2 / CeO2 hollow carbon sphere (60%) heterostructure electrocatalyst prepared in Example 5 was used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -36mV.

[0062] Comparative Example 1

[0063] Compared with Example 1, the difference is that step 4 is omitted, and only CeO2 hollow carbon spheres are prepared.

[0064] The application method is the same as in Example 1. Compared with the CeO2 hollow carbon sphere electrocatalyst prepared in Example 1, hydrogen is produced by electrocatalytically splitting water in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -579mV.

[0065] Comparative Example 2

[0066] Compared with Example 1, the difference is that steps 2-3 are omitted, CeO2 is not added in step 4, and only RuSe2 is prepared; the remaining steps are the same.

[0067] The application method is the same as in Example 1. Comparatively, the RuSe2 electrocatalyst prepared in Example 2 was used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -59mV.

[0068] Comparative Example 3

[0069] Compared with Example 1, the difference is that no carbon sphere template is added to prepare RuSe2 / CeO2 without hollow structure, while the other steps are the same.

[0070] The application method is the same as in Example 1. Compared with the RuSe2 / CeO2 electrocatalyst prepared in Example 3, hydrogen is produced by electrocatalytically splitting water in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 It exhibits a hydrogen evolution overpotential of -102 mV.

[0071] Comparative Example 4

[0072] Compared with Example 1, the only difference is that: after obtaining fresh RuSe2 / CeO2 hollow carbon spheres in step 4, the fresh RuSe2 / CeO2 hollow carbon spheres are placed in a tube furnace under N2 atmosphere and heated to 200℃, 300℃, 500℃, and 600℃ respectively at a heating rate of 5℃ / min. Then, they are calcined at 200℃, 300℃, 500℃, and 600℃ for 2 hours, and then cooled to room temperature at a cooling rate of 5℃ / min. Other operations are the same to obtain RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst.

[0073] The application method is the same as in Example 1. Comparatively, the RuSe2 / CeO2-200, RuSe2 / CeO2-300, RuSe2 / CeO2-500, and RuSe2 / CeO2-600 electrocatalysts prepared in Example 4 were used to electrocatalyze the splitting of water to produce hydrogen in an alkaline electrolyte of 1 mol / L KOH at a current density of -10 mA / cm². 2 The hydrogen evolution overpotentials were -107mV, -81mV, -100mV and -153mV, respectively.

[0074] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst, characterized in that, The specific steps of the preparation method are as follows: (1) First, carbon ball templates are prepared. The carbon ball templates, cerium nitrate hexahydrate and urea are dissolved in deionized water and ultrasonically dissolved evenly. The solution is transferred to a high-pressure reactor for reaction. After the reaction is completed and cooled naturally, the product is taken out, washed and dried to obtain CeO2 / C precursor. (2) The CeO2 / C precursor was calcined in a tube furnace under N2 atmosphere, and then calcined in a tube furnace under air atmosphere to obtain CeO2 hollow carbon spheres. (3) CeO2 hollow carbon spheres and Se powder were dispersed in deionized water and ultrasonically dispersed evenly. Then RuCl3·xH2O and hydrazine hydrate were added to the above solution in sequence and stirred to mix the solution evenly. The solution was transferred to a high-pressure reactor for reaction. After the reaction was completed and cooled naturally, the product was taken out, washed, and dried to obtain RuSe2 / CeO2 hollow carbon spheres. The RuSe2 / CeO2 hollow carbon spheres were calcined at 200℃~600℃ in N2 atmosphere to obtain RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst. The mass ratio of RuSe2 in the RuSe2 / CeO2 hollow carbon sphere heterostructure was 10%~60%.

2. The method for preparing RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst according to claim 1, characterized in that, Step (1) The molar ratio of carbon ball template, cerium nitrate hexahydrate and urea is 4:2:5; the reaction conditions in the high-pressure reactor are: reaction at 120 ℃ for 12 h.

3. The preparation method of the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst according to claim 1, characterized in that, Step (2) The calcination temperature is 400 ℃.

4. The preparation method of the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst according to claim 1, characterized in that, The reaction conditions in step (3) of the high-pressure reactor are: 120 °C for 12 h; the calcination temperature in step (3) is 400 °C and the heating rate is 5 °C / min.

5. The method for preparing the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst according to claim 1, characterized in that, The mass ratio of RuSe2 in the RuSe2 / CeO2 hollow carbon sphere heterostructure is 40%~60%.

6. The application of the RuSe2 / CeO2 hollow carbon sphere heterostructure electrocatalyst prepared by the preparation method according to any one of claims 1-5 in electrocatalytic hydrogen evolution.