A nickel-based rare earth composite electrocatalyst, a preparation method and application thereof

Abstract

This invention discloses a nickel-based rare earth composite electrocatalyst, its preparation method, and its application, belonging to the field of electrocatalyst technology. The electrocatalyst comprises a conductive substrate and a catalytically active surface layer attached to the conductive substrate; the catalytically active surface layer contains nickel and rare earth elements, with a molar ratio of nickel to rare earth elements of 90-99:0.5-10. This invention utilizes Joule heating technology to induce a uniform composite formation of nickel and rare earth elements, resulting in a nanocomposite structure with abundant interfaces and active sites. This electrocatalyst, used as an anode in the electrochemical oxidation reaction of glycerol, exhibits high catalytic activity and selectivity. It can replace the oxygen evolution reaction in the traditional water electrolysis process and, coupled with the hydrogen evolution reaction at the cathode, can significantly reduce the voltage of the entire electrolyzer while efficiently converting inexpensive glycerol into high-value-added chemicals such as formic acid, realizing the resource-based value-added of biomass byproducts and the co-production of green hydrogen energy.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology, and in particular to a nickel-based rare earth composite electrocatalyst, its preparation method, and its application. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Hydrogen energy is an ideal clean energy carrier, and water electrolysis is the mainstream technology for green hydrogen production. However, the slow kinetics and high overpotential of the oxygen evolution reaction at the anode lead to high system energy consumption, hindering its large-scale application. Meanwhile, the large-scale development of the biodiesel industry generates a large amount of glycerol as a byproduct, with limited existing channels for its disposal and low prices, resulting in resource waste and limiting the economic viability of the entire biomass energy industry chain. Replacing the oxygen evolution reaction (OER) with the lower thermodynamic potential of glycerol electro-oxidation and coupling it with the hydrogen evolution reaction at the cathode can convert glycerol into value-added chemicals such as formic acid while producing hydrogen, and is considered a highly promising solution.

[0004] The core of achieving the above goals lies in developing efficient, stable, and low-cost anodic GOR electrocatalysts. In existing technologies, nickel-based materials are the preferred non-precious metal catalysts for GOR due to their ability to generate highly active redox couples in situ under alkaline conditions. However, pure nickel and simple nickel-based oxides suffer from insufficient intrinsic activity at their active sites, poor adsorption-desorption performance for glycerol and its intermediates, poor selectivity in C / C bond breaking, and are prone to corrosion and deactivation due to active phase reconstruction during prolonged operation. To address these issues, researchers have adopted rare-earth element doping strategies, utilizing the unique electronic structure and oxygen storage / release capabilities of rare-earth elements to modulate the electronic properties of nickel. However, the preparation of existing nickel-rare-earth composite catalysts still relies on traditional methods such as co-precipitation, hydrothermal treatment, and impregnation-calcination, which are cumbersome, time-consuming, and energy-intensive. Furthermore, the rare-earth element doping effect is uneven or forms independent rare-earth oxide phases, failing to fully leverage the synergistic effect of the two, resulting in catalyst activity and selectivity that still do not meet practical application requirements.

[0005] Therefore, it is necessary to provide a highly active and selective GOR electrocatalyst. Summary of the Invention

[0006] In view of this, the present invention provides a nickel-based rare earth composite electrocatalyst, its preparation method and application.

[0007] In a first aspect, the present invention provides a nickel-based rare earth composite electrocatalyst, the electrocatalyst comprising a conductive substrate and a catalytically active surface layer attached to the conductive substrate; The catalytically active surface layer contains nickel and rare earth elements, and the molar ratio of nickel to rare earth elements is 90-99:0.5-10.

[0008] The content of rare earth elements affects catalytic activity, but catalytic performance does not necessarily increase with increasing rare earth content. When the rare earth element content is too low, it leads to sparse dispersion on the catalytic active surface, making it difficult to form an effective electronic coupling interface. This hinders precise control of the nickel electronic structure and the generation of sufficient oxygen vacancies. In this case, the active center of the catalyst is still dominated by pure nickel, and the intrinsic activity of the active sites remains insufficient, along with an imbalance in the adsorption-desorption of glycerol and its intermediates. When the rare earth element content is too high, it leads to excessive aggregation of rare earth elements on the catalytic active surface, forming localized rare earth oxide enrichment regions. These rare earth oxides themselves have low intrinsic activity for the electro-oxidation of glycerol and can cover or isolate some highly active nickel-based active sites, resulting in reduced exposure of effective active sites and decreased catalytic activity. Excessive rare earth content can lead to over-modification of the main electronic structure of nickel, resulting in excessive d-band center shift. This can increase the adsorption energy barrier of glycerol and its intermediates at active sites, causing difficulties in intermediate desorption and carbon buildup that clogs active sites. Simultaneously, excessive electron transfer can disrupt the stability of the NiOOH / Ni(OH)₂ redox couple, which is crucial for the electro-oxidation of glycerol in nickel-based catalysts. Decreased stability of this couple further reduces catalytic activity. Therefore, a molar ratio of nickel to rare earth elements of 90-99:0.5-10 allows for uniform dispersion of rare earth elements on the nickel-based active surface. This avoids insufficient synergy due to low content and excessive coverage of active sites due to high content. At this ratio, rare earth elements can precisely regulate the d-band center of nickel through electron transfer, optimizing the adsorption / desorption balance of intermediates while introducing sufficient oxygen vacancies to accelerate the supply of active oxygen species. The rare earth elements form a stable composite phase with nickel, effectively exposing highly active nickel-based sites, thus balancing catalytic activity, selectivity, and stability for efficient glycerol electro-oxidation.

[0009] Preferably, the conductive substrate is selected from carbon cloth, carbon fiber paper, or carbon felt; The rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium, and samarium.

[0010] Preferably, the molar ratio of nickel to rare earth elements is 98-99:1-2. Within this molar ratio range, excellent catalytic performance in the electro-oxidation of glycerol is exhibited.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned nickel-based rare earth composite electrocatalyst, comprising the following steps: (1) The conductive substrate is hydrophilized; (2) Dissolve nickel salt and rare earth metal salt in solvent to prepare a precursor solution, immerse the treated conductive substrate in the precursor solution, and then dry to obtain a substrate loaded with precursor. (3) The substrate of the supported precursor is subjected to Joule pyrolysis under vacuum or inert atmosphere to obtain the nickel-based rare earth composite electrocatalyst.

[0012] This invention utilizes a rapid Joule heating technique to successfully introduce highly dispersed trace amounts of rare earth elements into a nickel matrix. These trace rare earth elements do not form independent crystalline phases but rather exist in the nickel matrix or on its surface in a highly dispersed amorphous state or as atomic clusters, thus preparing an electrocatalyst with a composite structure of nanocrystalline nickel and amorphous / atomic-level dispersed rare earth elements. This structure maximizes the interaction interface between nickel and rare earth elements, creating ideal conditions for electronic structure modulation and synergistic catalytic effects.

[0013] Preferably, in step (1), the hydrophilization treatment specifically includes: placing the conductive substrate in an acidic solution, then performing hydrothermal treatment under a sealed environment, cooling to room temperature after the reaction is completed, removing it, and washing it with deionized water.

[0014] Preferably, in step (1), the acidic solution is selected from nitric acid solution, hydrochloric acid solution, sulfuric acid solution, phosphoric acid solution, hydrobromic acid solution or perchloric acid, and the concentration of the acidic solution is 0.05-0.5 M; In step (1), the hydrothermal treatment temperature is 160-180℃ and the hydrothermal treatment time is 10-12 h.

[0015] Preferably, in step (2), the nickel salt is nickel nitrate, nickel chloride, or nickel sulfate; In step (2), the rare earth metal salt is a nitrate, chloride, or acetate of a rare earth element; In step (2), the solvent is selected from one or more of water and ethanol; In step (2), the total concentration of nickel salt and rare earth metal salt in the precursor solution is 0.5-2 mol / L; In step (2), the soaking time is 5-10 min and the drying temperature is 40-60℃.

[0016] Preferably, in step (3), the Joule heating pyrolysis treatment temperature is 1000-1600℃, the heating time is 0.1-1s, and the heating rate is 1000-10000℃ / s.

[0017] Secondly, the present invention provides the application of the above-mentioned nickel-based rare earth composite electrocatalyst and the electrocatalyst prepared by the above-mentioned preparation method in the electrocatalytic oxidation of glycerol.

[0018] Preferably, in the electro-oxidation process, the working electrode is the nickel-based rare earth composite electrocatalyst described above, the electrocatalyst prepared by the above preparation method, the reference electrode is an Hg / HgO electrode, an Ag / AgCl electrode, or a reversible hydrogen electrode, the counter electrode is a platinum sheet, and the electrolyte is a mixed solution of 1M potassium hydroxide and 0.05-0.15 M glycerol.

[0019] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) This invention introduces rare earth elements to form a nickel-based rare earth composite electrocatalyst by combining them with nickel. Rare earth elements have a unique 4f electron layer structure, which can regulate the d-band center of nickel through electronic interactions when combined with nickel. This regulation of electronic structure optimizes the adsorption strength of oxygen-containing intermediates on the catalyst surface, making it easier for glycerol molecules to be adsorbed on the catalyst surface and react, thereby reducing the onset potential of the glycerol electro-oxidation reaction.

[0020] (2) The preparation method of the electrocatalyst of this invention breaks through the limitations of traditional synthesis processes. By utilizing the characteristics of Joule heating technology for ultra-fast heating and second-level processing, the instantaneous pyrolysis and alloying of nickel salt and rare earth metal salt on a conductive substrate are achieved. This promotes the formation of uniform composites between nickel and rare earth elements, which helps to form nanostructures or amorphous structures with abundant defects and high specific surface area. This facilitates the exposure of more active sites and enhances stability, allowing more glycerol molecules to simultaneously contact and react with the active sites on the catalyst surface. At the same time, the Joule heating rapid synthesis technology shortens the high-temperature heat treatment process, which can take several hours or even tens of hours, to the second level. The heating rate is extremely fast, and the entire process does not require an external heating furnace, which greatly simplifies the process flow and reduces energy consumption and equipment costs.

[0021] (3) The electrocatalyst of the present invention is used as the anode for the electrochemical oxidation reaction of glycerol, exhibiting high catalytic activity and selectivity. It can replace the oxygen evolution reaction in the traditional water electrolysis process and couple with the hydrogen evolution reaction at the cathode. It can significantly reduce the voltage of the entire electrolyzer while efficiently converting cheap glycerol into high-value-added chemicals such as formic acid, realizing the resource-based value-added of biomass by-products and the co-production of green hydrogen energy. Attached Figure Description

[0022] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0023] Figure 1 The X-ray diffraction (XRD) pattern of the nickel-cerium composite electrocatalyst prepared in Example 1 of this invention; Figure 2 This is a scanning electron microscope image of the nickel-cerium composite electrocatalyst prepared in Example 1 of the present invention; Figure 3 The LSV curves of Examples 1-7 and Comparative Example 1 of this invention in 1 M KOH and 0.1 M glycerol (1 M KOH) electrolytes are shown. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] The technical solution of the present invention will be further described below with reference to specific embodiments. The present invention does not impose any special restrictions on the source of reagents used in the following embodiments; commercially available products well known to those skilled in the art can be used.

[0026] Example 1 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0027] Accurately weigh 0.02475 mol of Ni(NO3)2·6H2O and 0.00025 mol of Ce(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-cerium precursor.

[0028] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0029] Example 2 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0030] Accurately weigh 0.02475 mol of Ni(NO3)2·6H2O and 0.00025 mol of La(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40 °C for 12 hours to obtain carbon cloth loaded with the nickel-lanthanum precursor.

[0031] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0032] Example 3 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0033] Accurately weigh 0.02475 mol of Ni(NO3)2·6H2O and 0.00025 mol of Pr(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-praseodymium precursor.

[0034] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0035] Example 4 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0036] Accurately weigh 0.02475 mol of Ni(NO3)2·6H2O and 0.00025 mol of Nd(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-neodymium precursor.

[0037] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0038] Example 5 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0039] Accurately weigh 0.02425 mol of Ni(NO3)2·6H2O and 0.00075 mol of Ce(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-cerium precursor.

[0040] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0041] Example 6 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0042] Accurately weigh 0.02375 mol of Ni(NO3)2·6H2O and 0.00125 mol of Ce(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-cerium precursor.

[0043] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0044] Example 7 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0045] Accurately weigh 0.0225 mol of Ni(NO3)2·6H2O and 0.0025 mol of Ce(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the impregnated carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel-cerium precursor.

[0046] The dried sample was placed between the two electrodes of the Joule heating rapid synthesis apparatus and fixed in place. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment.

[0047] Comparative Example 1 Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0048] Accurately weigh 0.025 mol of Ni(NO3)2·6H2O, dissolve it in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the impregnated carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40°C for 12 hours to obtain carbon cloth loaded with the nickel precursor.

[0049] The dried sample was placed between the two electrodes of the Joule thermal rapid synthesis apparatus and fixed. The reaction chamber was closed, and a vacuum was drawn until the pressure was below 10 Pa. The target temperature was set to 1600℃, the heating time to 1s, and the heating rate to 1600℃ / s, so that the temperature could be rapidly reached. At this point, the power was turned off to stop heating, and the sample was allowed to cool naturally in a vacuum environment to obtain a pure nickel electrocatalyst.

[0050] Comparative Example 2 Same as Example 1, except that in the preparation of nickel-cerium composite electrocatalyst, Joule heating pyrolysis is replaced by conventional tube furnace heating pyrolysis.

[0051] Cut a piece of carbon cloth measuring 1 cm × 4 cm, place it in a 50 mL polytetrafluoroethylene liner, add 35 mL of 0.1 M nitric acid solution, seal the container, and place it in a stainless steel autoclave. Place the autoclave in an oven and react at 160°C for 12 hours. After the reaction is complete, allow it to cool naturally to room temperature, remove the carbon cloth, and wash it repeatedly with deionized water until neutral.

[0052] Accurately weigh 0.02475 mol of Ni(NO3)2·6H2O and 0.00025 mol of La(NO3)2·6H2O, dissolve them together in 50 mL of ultrapure water, and stir magnetically for 30 minutes to obtain a clear solution with a total metal ion concentration of 0.5 M. Completely immerse the pretreated carbon cloth in this solution and allow it to stand for 5 minutes to ensure the solution fully wets the carbon cloth. Remove the immersed carbon cloth, remove excess liquid droplets from the surface, and then place it in a clean centrifuge tube. Dry it in a vacuum drying oven at 40 °C for 12 hours to obtain carbon cloth loaded with the nickel-lanthanum precursor.

[0053] The dried sample was placed in a tube furnace and heated to 600℃ at a heating rate of 10 ℃ / min, and held at 600℃ for 1 hour. During the heating process, argon gas (flow rate 50 sccm) was continuously introduced to maintain an inert atmosphere. After the heat treatment, the sample was naturally cooled to room temperature in an argon atmosphere, resulting in a nickel-cerium composite electrocatalyst prepared by a conventional tube furnace heating method, denoted as Comparative Example 2.

[0054] Performance testing Please see Figure 1The X-ray diffraction (XRD) pattern of the nickel-cerium composite electrocatalyst prepared in Example 1 of this invention is shown. The pattern reveals no obvious sharp crystalline phase diffraction peaks against an amorphous background of carbon cloth, indicating the formation of a nanocrystalline or amorphous composite structure. A set of broadened diffraction peaks was observed in the diffraction angle range of 20° to 80°. Comparison with the standard card (JCPDS No. 04-0850) confirmed that these diffraction peaks belong to face-centered cubic metallic nickel (Ni). The significant broadening of the diffraction peaks indicates that after rapid Joule heating, metallic nickel exists in nanocrystalline form with a small grain size. Notably, no distinct diffraction peaks belonging to crystalline cerium dioxide (CeO2) or other cerium compounds were detected in the pattern. This phenomenon suggests that under Joule heating conditions, trace amounts of cerium do not form independent crystalline phases but may exist in a highly dispersed amorphous state or in the form of atomic clusters within the nickel matrix or on the surface. This structure is beneficial for maximizing the interaction interface between nickel and cerium species, creating ideal conditions for electronic structure modulation and synergistic catalytic effects. Meanwhile, the active material is uniformly loaded onto the surface of the carbon fiber, forming a porous and interconnected microstructure, which helps to expose active sites and promote mass transfer.

[0055] Please see Figure 2 Scanning electron microscope image of the nickel-cerium composite electrocatalyst prepared in Example 1 of this invention. Figure 2 This is a scanning electron microscope image of the nickel-cerium composite electrocatalyst prepared in Example 1 of the present invention at a magnification of 7.00 k. The image shows that the carbon cloth fiber surface is uniformly and densely coated with the catalyst layer, forming a typical skin-core structure. This indicates a good interfacial bond between the active material and the substrate, which is beneficial to the structural stability of the catalyst during long-term electrolysis.

[0056] Further observation of the microstructure of the catalyst layer reveals that it is composed of tightly packed nanoparticles with a size of 50-150 nm, forming a rich three-dimensional porous network structure between the particles. This nanoparticle packing morphology is a typical product of the Joule thermal rapid synthesis process—the extremely fast heating rate (1600℃ / s) and second-level processing time cause the nickel salt and cerium salt to pyrolyze instantly, while effectively inhibiting the excessive growth of grains, thereby obtaining a fine nanocrystalline structure. The mesoporous-macroporous network formed by particle packing has the following electrocatalytic advantages: (1) high specific surface area, allowing more nickel active sites to be exposed; (2) promoting electrolyte penetration and diffusion of glycerol molecules, reducing concentration polarization; (3) facilitating the rapid desorption of the product formic acid, avoiding the occupation of active sites; and (4) providing a release channel for possible gases.

[0057] Furthermore, the nanoparticles exhibit a certain degree of surface roughness, attributed to atomic-level defect sites generated by the rapid decomposition of the precursor and the instantaneous escape of gas during Joule heating. These defect sites typically possess unsaturated coordination environments, which are more favorable for the adsorption and activation of glycerol molecules and oxygen-containing intermediates. Combined with the XRD results (no independent crystalline CeO2 phase detected), it can be inferred that cerium is uniformly distributed in the nickel matrix in a highly dispersed amorphous state or in the form of atomic clusters. No obvious two-phase separation or large-sized agglomerates were observed in the SEM images, confirming that the Joule heating method achieved uniform composite formation of nickel and rare earth elements.

[0058] Therefore, this invention successfully constructed a porous nickel-cerium composite catalytic layer composed of stacked nanoparticles via a Joule heating rapid synthesis method. This structure combines high active area, excellent mass transfer performance, abundant defect sites, and uniform elemental distribution, providing an ideal structural platform for the efficient electro-oxidation of glycerol. It is an important structural basis for the catalyst to achieve low onset potential (1.16V vs. RHE) and high formic acid selectivity.

[0059] Test case Electrochemical tests were performed on a Chenhua CHI760E electrochemical workstation using a standard three-electrode system: the catalysts prepared in the examples and comparative examples were used as the working electrode (effective area 0.25 cm²). 2 A platinum sheet was used as the counter electrode, and Hg / HgO (1 M KOH) was used as the reference electrode. The electrolyte was 1 M KOH + 0.1 M glycerol. Linear sweep voltammetry (LSV) was performed. The test results are shown below. Figure 3 See Table 1.

[0060] Table 1 Test Results

[0061] Test results show that Examples 1-7 exhibited good GOR catalytic performance. Among them, the electrode in Example 1 achieved 10 mA cm⁻¹. -2 The required potential for the current density is 1.16 V vs. RHE, exhibiting excellent electro-oxidation activity of glycerol.

[0062] By comparing the data from Examples 1-7 and Comparative Example 1, it is shown that the introduction of rare earth metals greatly improves the glycerol electro-oxidation activity of the catalyst.

[0063] By comparing the data from Examples 1, 5, 6, 7 and Comparative Example 1, it is shown that the introduction of extremely low amounts of rare earth metals greatly improves the glycerol electro-oxidation activity of the catalyst.

[0064] By comparing the data in Example 1 and Comparative Example 2, it is shown that Joule pyrolysis treatment is beneficial to improving the glycerol electro-oxidation activity of the catalyst.

[0065] The selectivity test method for glycerol electro-oxidation products: The products are analyzed by liquid chromatography, and the content of each product is the selectivity. The specific distribution of glycerol electro-oxidation products is shown in Table 2.

[0066] Table 2

[0067] Stability testing: Electrochemical tests were conducted on a Chenhua CHI760E electrochemical workstation using a standard three-electrode system. The catalyst prepared in Example 1 was used as the working electrode (effective area 0.25 cm²). 2 A platinum sheet was used as the counter electrode, and Hg / HgO (1M KOH) was used as the reference electrode. The electrolyte was 1 M KOH + 0.1 M glycerol. Example 1 was subjected to a long-term glycerol electro-oxidation reaction test, and the catalyst showed no deactivation during a stability test lasting up to 800 hours.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nickel-based rare earth composite electrocatalyst, characterized in that, The electrocatalyst includes a conductive substrate and a catalytically active surface layer attached to the conductive substrate; The catalytically active surface layer contains nickel and rare earth elements, and the molar ratio of nickel to rare earth elements is 90-99:0.5-10.

2. The nickel-based rare earth composite electrocatalyst as described in claim 1, characterized in that, The conductive substrate is selected from carbon cloth, carbon fiber paper or carbon felt. The rare earth element is selected from one or more of cerium, lanthanum, praseodymium, neodymium, and samarium.

3. The nickel-based rare earth composite electrocatalyst as described in claim 1, characterized in that, The molar ratio of nickel to rare earth elements is 98-99:1-2.

4. The preparation method of the nickel-based rare earth composite electrocatalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The conductive substrate is hydrophilized; (2) Dissolve nickel salt and rare earth metal salt in solvent to prepare a precursor solution, immerse the treated conductive substrate in the precursor solution, and then dry to obtain a substrate loaded with precursor. (3) The substrate of the supported precursor is subjected to Joule pyrolysis under vacuum or inert atmosphere to obtain the nickel-based rare earth composite electrocatalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the hydrophilization treatment specifically includes: placing the conductive substrate in an acidic solution, then performing hydrothermal treatment under a sealed environment, cooling to room temperature after the reaction is completed, removing it, and washing it with deionized water.

6. The preparation method according to claim 5, characterized in that, In step (1), the acidic solution is selected from nitric acid solution, hydrochloric acid solution, sulfuric acid solution, phosphoric acid solution, hydrobromic acid solution or perchloric acid, and the concentration of the acidic solution is 0.05-0.5 M; In step (1), the hydrothermal treatment temperature is 160-180℃ and the hydrothermal treatment time is 10-12 h.

7. The preparation method according to claim 4, characterized in that, In step (2), the nickel salt is nickel nitrate, nickel chloride, or nickel sulfate; In step (2), the rare earth metal salt is a nitrate, chloride, or acetate of a rare earth element; In step (2), the solvent is selected from one or more of water and ethanol; In step (2), the total concentration of nickel salt and rare earth metal salt in the precursor solution is 0.5-2 mol / L; In step (2), the soaking time is 5-10 min and the drying temperature is 40-60℃.

8. The preparation method according to claim 4, characterized in that, In step (3), the Joule heating pyrolysis treatment temperature is 1000-1600℃, the heating time is 0.1-1s, and the heating rate is 1000-10000℃ / s.

9. The application of the nickel-based rare earth composite electrocatalyst according to any one of claims 1 to 3 and the electrocatalyst prepared by the preparation method according to any one of claims 4 to 8 in the electrocatalytic oxidation of glycerol.

10. The application according to claim 9, characterized in that, During the electro-oxidation process, the working electrode is the nickel-based rare earth composite electrocatalyst according to any one of claims 1 to 3, or the electrocatalyst prepared by the preparation method according to any one of claims 4 to 8. The reference electrode is an Hg / HgO electrode, an Ag / AgCl electrode, or a reversible hydrogen electrode. The counter electrode is a platinum sheet. The electrolyte is a mixed solution of 1M potassium hydroxide and 0.05-0.15 M glycerol.

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