Nickel cobalt phosphide catalytic electrode for glycerol oxidation and preparation method and application thereof

Abstract

The application discloses a nickel-cobalt phosphide catalytic electrode which can be used for glycerol oxidation and a preparation method and application thereof, and belongs to the technical field of electrocatalysis. The preparation method comprises the following steps: S1, adding nickel salt, cobalt salt, ammonium fluoride and urea into water and stirring until they are uniformly mixed, and then performing a hydrothermal reaction on the mixture with a foamed nickel substrate to obtain a nickel-cobalt bimetallic hydroxide precursor loaded on the foamed nickel; and S2, placing the nickel-cobalt bimetallic hydroxide precursor loaded on the foamed nickel and sodium hypophosphite in an inert atmosphere and performing a low-temperature phosphorization treatment, and thus the nickel-cobalt phosphide catalytic electrode is obtained. The preparation method is low in cost and easy to operate, and the prepared nickel-cobalt phosphide catalytic electrode can be used as a bifunctional catalyst and has excellent HER and GOR catalytic activities, so that glycerol assisted hydrogen production can be realized at a low voltage, and the effective combination of energy conversion and high-value chemical production is realized.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, and in particular to a nickel-cobalt phosphide catalytic electrode for glycerol oxidation, 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] With the growth of global energy demand and the increasing prominence of environmental problems, the development of clean, efficient, and sustainable energy technologies is of paramount importance. Hydrogen, due to its high energy density and zero carbon emissions, is considered an ideal future energy carrier. Among numerous hydrogen production technologies, water electrolysis has attracted considerable attention due to its relatively simple process and high product purity. However, the anodic process of traditional water electrolysis—the oxygen evolution reaction (OER)—involves complex four-electron transfer steps, resulting in extremely slow reaction kinetics and the need to overcome a high overpotential (theoretical potential 1.23 V vs. RHE). This leads to persistently high energy consumption in the overall hydrogen production process, becoming one of the main bottlenecks limiting its large-scale application.

[0004] To reduce hydrogen production energy consumption, an effective strategy is to replace OER with thermodynamically more easily oxidized substances. Glycerol, a biomass derivative and a major byproduct of biodiesel production, is not only widely available and inexpensive, but its theoretical oxidation potential (GOR) (0.003 V vs. RHE) is also much lower than that of OER. More importantly, glycerol oxidation can produce high-value-added chemicals such as glyceric acid and formic acid, thus achieving the dual goals of low-energy hydrogen production and high-value chemical production. Currently, highly efficient GOR catalysts are mostly based on precious metals (such as Pt, Pd, and Au), but their high cost and scarcity severely hinder practical application. Therefore, developing bifunctional catalysts based on non-precious metals, possessing both high activity and stability, especially catalysts capable of simultaneously and efficiently catalyzing both the cathode hydrogen evolution reaction (HER) and the anodic glycerol oxidation reaction (GOR), is of great significance for promoting the development of biomass-assisted hydrogen production technology. Summary of the Invention

[0005] In view of this, the present invention provides a nickel-cobalt phosphide catalytic electrode that can be used for glycerol oxidation, a method for preparing the electrode, and its application.

[0006] In a first aspect, the present invention provides a method for preparing a nickel-cobalt phosphide catalytic electrode that can be used for glycerol oxidation, comprising the following steps: S1. Add nickel salt, cobalt salt, ammonium fluoride and urea to water and stir evenly, then carry out hydrothermal reaction with nickel foam substrate to obtain nickel cobalt bimetallic hydroxide precursor loaded on nickel foam. S2. The nickel-cobalt bimetallic hydroxide precursor loaded on nickel foam and sodium hypophosphite are placed in an inert atmosphere and subjected to low-temperature phosphating treatment to obtain the final product.

[0007] Preferably, in S1, the mass ratio of nickel salt, cobalt salt, ammonium fluoride and urea is 0.8-1.2:0.8-1.2:1:3.5-4.5.

[0008] Preferably, in S1, the mass ratio of ammonium fluoride to the volume ratio of water is 0.444 g: 25-35 mL.

[0009] Preferably, in S1, the nickel salt is nickel nitrate hexahydrate, and the cobalt salt is selected from cobalt nitrate hexahydrate.

[0010] Preferably, in S1, the hydrothermal reaction temperature is 100–140°C and the time is 4–8 hours.

[0011] Preferably, in S2, the low-temperature phosphating temperature is 300-400℃ and the low-temperature phosphating time is 1-3h.

[0012] Preferably, in S2, the heating rate during the low-temperature phosphating process is 2–5 °C / min.

[0013] Preferably, in S2, the protective atmosphere is either high-purity argon or high-purity nitrogen, and the amount of sodium hypophosphite used is 0.1-1g.

[0014] Secondly, the present invention also provides a nickel-cobalt phosphide catalytic electrode for glycerol oxidation prepared by the above-mentioned method for preparing a nickel-cobalt phosphide catalytic electrode for glycerol oxidation.

[0015] Thirdly, the present invention also provides a nickel-cobalt phosphide catalytic electrode for glycerol oxidation prepared by the above-described preparation method, or the application of the above-described nickel-cobalt phosphide catalytic electrode for glycerol oxidation in glycerol-assisted hydrogen production.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) This invention involves a hydrothermal reaction of nickel salts, cobalt salts, ammonium fluoride, and urea with a nickel foam substrate to grow a nickel-cobalt bimetallic hydroxide precursor in situ, which is then converted into a nickel-cobalt phosphide catalytic electrode via low-temperature phosphating. In this process, the nickel foam substrate directly participates in the reaction as a conductive substrate, avoiding the addition of additional binders and ensuring close contact between the catalyst and the substrate structurally, thus achieving rapid charge transfer. Furthermore, the synergistic doping of nickel and cobalt bimetals can regulate the Ni²⁺ content. + / Ni³+ The electronic structure of the redox couple was optimized to improve the adsorption energy of intermediates in the glycerol oxidation and hydrogen evolution reactions, thus lowering the reaction energy barrier. Simultaneously, the synergistic effect of ammonium fluoride and urea induced the formation of a spiny nanowire array structure. This structure possesses a large specific surface area and open pores, significantly increasing the number of active sites and accelerating electrolyte penetration and reaction bubble desorption, thereby improving catalytic efficiency from a kinetic perspective. Ultimately, a bifunctional and highly efficient non-precious metal catalyst was achieved, reducing the energy consumption of glycerol-assisted hydrogen production without the need for precious metals, and solving the technical problems of high cost and insufficient activity of existing catalysts.

[0017] (2) After hydrothermal and phosphating treatment, a nickel-cobalt bimetallic phosphide was formed. There is a significant electronic synergistic effect between nickel and cobalt. This effect can regulate the electronic structure of the active sites, thereby optimizing the adsorption capacity for glycerol molecules and reaction intermediates, avoiding poisoning of active sites due to excessive adsorption or difficulty in initiating the reaction due to insufficient adsorption. Compared to single-metal phosphides, this invention effectively reduces the onset potential and reaction barrier of the glycerol oxidation reaction (GOR) through bimetallic synergistic effects, significantly improving catalytic kinetics.

[0018] (3) The preparation method of the present invention is low in cost and easy to operate. The prepared nickel cobalt phosphide catalytic electrode can be used as a bifunctional catalyst, with excellent HER and GOR catalytic activity. It can realize glycerol-assisted hydrogen production under low voltage, realizing an effective combination of energy conversion and high value-added chemical production. Attached Figure Description

[0019] 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.

[0020] Figure 1 The images shown are scanning electron microscope (SEM) images of the nickel-cobalt bimetallic hydroxide precursor prepared in Example 1 of the present invention, where a is a low-magnification SEM image and b is a high-magnification SEM image. Figure 2 The images shown are scanning electron microscope (SEM) images of the NiCoP / NF catalytic electrode prepared in Example 1 of the present invention, where a is a low-magnification SEM image and b is a high-magnification SEM image. Figure 3 The elemental distribution map of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention is shown below. Figure 4 The X-ray diffraction (XRD) pattern of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention. Figure 5The energy dispersive spectroscopy (EDS) spectrum of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention is shown. Figure 6 The image shows the HER linear sweep voltammetry curves of the NiCoP / NF catalytic electrode and the nickel foam substrate prepared in Example 1 of this invention in 1.0 M KOH electrolyte. Figure 7 The linear sweep voltammetry curve of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention in 1.0 M KOH electrolyte is shown. Figure 8 The Tafel slope diagram is shown for the NiCoP / NF catalytic electrode prepared in Example 1 of this invention during the glycerol oxidation reaction. Figure 9 The stability test curve of the NiCoP / NF catalytic electrode prepared in Example 1 of the invention during the glycerol oxidation reaction is shown. Figure 10 The in-situ Raman spectrum of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention during the glycerol oxidation reaction; Figure 11 The image shows the linear sweep voltammetry curve of the NiCoP / NF catalytic electrode prepared in Example 1 of this invention in a two-electrode system. Detailed Implementation

[0021] 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.

[0022] This invention provides a method for preparing a nickel-cobalt-phosphide catalytic electrode that can be used for glycerol oxidation, comprising the following steps: S1. Add nickel salt, cobalt salt, ammonium fluoride and urea to water and stir evenly, then carry out hydrothermal reaction with nickel foam substrate to obtain nickel cobalt bimetallic hydroxide precursor loaded on nickel foam. S2. The nickel-cobalt bimetallic hydroxide precursor loaded on nickel foam and sodium hypophosphite are placed in an inert atmosphere and subjected to low-temperature phosphating treatment to obtain the final product.

[0023] This invention constructs an integrated electrode structure through an in-situ growth strategy, combining the synergistic effect of nickel-cobalt bimetals and the unique three-dimensional nanomorphology to achieve highly efficient bifunctional electrocatalysis for the hydrogen evolution reaction (HER) and the glycerol oxidation reaction (GOR).

[0024] Specifically, the spiky leaf-like nanowire array structure possesses a large specific surface area and an open porous structure, which facilitates electrolyte penetration and rapid desorption of reaction products, while providing abundant catalytic active sites. The electronic synergy between the nickel and cobalt bimetals optimizes the adsorption energy of intermediates and lowers the reaction energy barrier. The integrated electrode structure eliminates the need for external binders, ensuring close contact between the catalyst and the conductive substrate and promoting rapid electron transport. This preparation method is low-cost and simple to operate. The resulting catalytic electrode exhibits excellent HER and GOR bifunctional catalytic performance in alkaline electrolytes and can achieve glycerol-assisted hydrogen production at relatively low voltages.

[0025] In an optional embodiment of the present invention, in S1, the mass ratio of nickel salt, cobalt salt, ammonium fluoride and urea is 0.8-1.2:0.8-1.2:1:3.5-4.5.

[0026] Specifically, this particular ratio range is crucial for forming a uniform and morphology-controllable nickel-cobalt bimetallic hydroxide precursor. If the nickel / cobalt salt ratio is too high, it may lead to segregation of the single metallic phase, weakening the bimetallic synergistic effect; if the ratio is too low, the active site density will be insufficient. Meanwhile, ammonium fluoride acts as a morphology guide and etching agent, and urea acts as an alkali source and precipitant; their ratio with the metal salt precisely controls the nucleation and growth rates. Limiting the mass ratio of each component within the aforementioned range ensures the uniform and stable generation of a precursor with the target spiny leaf-like nanowire array structure during the hydrothermal reaction, laying the foundation for ultimately obtaining highly catalytically active nickel-cobalt phosphide.

[0027] In an optional embodiment of the present invention, in S1, the mass ratio of the ammonium fluoride to the volume ratio of the water is 0.444 g: 25-35 mL.

[0028] Specifically, this parameter essentially controls the concentration of the precursor solution in the hydrothermal reaction. The concentration of the reaction solution directly affects the supersaturation during the hydrothermal process, thus determining the nucleation density and growth orientation of the precursor nanowires. When the amount of water is too high (too low concentration), the nucleation rate is slow, which may result in insufficient loading and a sparse array on the nickel foam substrate; when the amount of water is too low (too high concentration), the reaction is too vigorous, which can easily cause nanowires to aggregate or form irregular blocky structures, destroying the spiny leaf-like morphology. By controlling the amount of water within the range of 25-35 mL per 0.444 g of ammonium fluoride, a uniform, dense, and regularly morphologically regular nanowire array can be obtained on the nickel foam, thereby maximizing the exposure of active sites.

[0029] In an optional embodiment of the present invention, in S1, the nickel salt is nickel nitrate hexahydrate, and the cobalt salt is selected from cobalt nitrate hexahydrate.

[0030] In an optional embodiment of the present invention, in S1, the temperature of the hydrothermal reaction is 100-140°C and the time is 4-8 hours.

[0031] Specifically, the hydrothermal reaction conditions are crucial for controlling the crystallinity, morphology, and phase composition of the precursor. When the temperature is below 100℃ or the reaction time is less than 4 hours, the reaction kinetics are insufficient, urea hydrolysis is incomplete, the amount of precursor loaded on the nickel foam is small and the crystallinity is poor, and even the formation of a complete nanowire structure is impossible. When the temperature is above 140℃ or the reaction time is longer than 8 hours, the reaction is too vigorous, which may lead to excessive growth of nanowires, aggregation, or detachment from the substrate, and may also promote the formation of inactive phases. By limiting the reaction temperature and time to the ranges of 100–140℃ and 4–8 hours, respectively, it is possible to ensure sufficient and uniform growth of the precursor while precisely controlling the formation of a nanowire array structure with spiky features.

[0032] In an optional embodiment of the present invention, in S2, the temperature of low-temperature phosphating is 300-400°C, and the low-temperature phosphating time is 1-3 hours.

[0033] Specifically, the phosphating process is crucial for converting the precursor into nickel-cobalt phosphide. This specific temperature and time range ensures complete precursor conversion and phase purity: below 300°C, complete phosphating of the precursor is difficult, and residual hydroxides reduce the catalyst's conductivity and catalytic activity; above 400°C, the thorn-like nanowire array structure collapses, disrupting the large specific surface area and open pore structure. Matching the reaction time with the temperature parameters ensures that sodium hypophosphite provides sufficient phosphorus to complete the conversion of nickel-cobalt bimetallic hydroxide to nickel-cobalt phosphide, while avoiding excessively long reactions that could lead to phosphide decomposition or morphological damage. This guarantees the phase purity and structural integrity of the catalytic electrode, improving its catalytic durability under alkaline conditions.

[0034] In an optional embodiment of the present invention, in S2, the heating rate during the low-temperature phosphating process is 2 to 5 °C / min.

[0035] Specifically, the heating rate directly affects the growth rate and phase formation of nickel-cobalt phosphides during the phosphating process: this rate range can ensure uniform temperature distribution within the tubular furnace, avoiding the collapse of nanostructures caused by local overheating, and also ensure the gradual decomposition of sodium hypophosphite to generate phosphorus sources, allowing phosphorus to fully react with the precursor to form nickel-cobalt phosphides with high purity and suitable crystallinity; at the same time, a suitable heating rate can avoid stress concentration caused by excessively rapid heating, maintain the integrity of the thorn-like nanowire array structure, and ensure the stability of the electronic conduction performance and catalytic activity of the catalytic electrode.

[0036] In an optional embodiment of the present invention, in S2, the protective atmosphere is either high-purity argon or high-purity nitrogen, and the amount of sodium hypophosphite used is 0.1-1g.

[0037] The present invention also provides a nickel-cobalt phosphide catalytic electrode for glycerol oxidation prepared by the above-described method.

[0038] The catalytic electrode is composed of a nickel-cobalt phosphide spiny leaf-shaped nanowire array grown in situ on nickel foam. It has a three-dimensional open structure and excellent electronic conductivity, and can exhibit excellent catalytic performance in the glycerol oxidation reaction, thus achieving efficient glycerol-assisted hydrogen production.

[0039] The present invention also provides a nickel-cobalt phosphide catalytic electrode prepared by the above-described preparation method that can be used for glycerol oxidation, or the application of the above-described nickel-cobalt phosphide catalytic electrode that can be used for glycerol oxidation in glycerol-assisted hydrogen production.

[0040] This catalytic electrode, used in HER and GOR processes under alkaline conditions, can significantly reduce the voltage input for hydrogen electrolysis, enabling the integration of efficient and energy-saving hydrogen production with the value-added conversion of biomass-derived chemicals.

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments. In the following embodiments, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, ammonium fluoride, urea, sodium hypophosphite, etc., were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Other raw materials or processing technologies not specifically mentioned are indicated as conventional commercially available products or conventional processing technologies in the art. Before use, the foamed nickel was ultrasonically cleaned for 10 minutes each in acetone, ethanol, and deionized water.

[0042] Electrochemical data were collected using CHI760E (Shanghai Chenhua).

[0043] Example 1: This embodiment provides a nickel-cobalt-phosphide catalytic electrode (NiCoP / NF), the preparation method of which is as follows: S1. Weigh 0.436 g of nickel nitrate hexahydrate, 0.437 g of cobalt nitrate hexahydrate, 0.444 g of ammonium fluoride, and 1.802 g of urea, and dissolve them in 30 mL of deionized water. Stir vigorously for 30 minutes to form a homogeneous mixed solution. Transfer this solution to a polytetrafluoroethylene-lined reactor containing pretreated nickel foam (size: 2 cm × 3 cm), seal it, and perform a hydrothermal reaction at 120 °C for 6 h. After naturally cooling to room temperature, remove the nickel foam, wash it three times each with deionized water and anhydrous ethanol, and dry it overnight in a vacuum drying oven at 60 °C to obtain the nickel-cobalt bimetallic hydroxide precursor (NiCo-LDH / NF) loaded on the nickel foam.

[0044] S2. Place 300 mg of sodium hypophosphite upstream of a tube furnace, and place the NiCo-LDH / NF obtained in S1 downstream of the tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a heating rate of 3 °C / min, hold for 2 h, and then allow to cool naturally to room temperature to obtain the target product, nickel cobalt phosphide catalytic electrode, denoted as NiCoP / NF.

[0045] Example 2: This embodiment is basically the same as Example 1, except that the hydrothermal reaction conditions in S1 are different. Specifically, the hydrothermal reaction temperature in S1 is 100℃ and the time is 8 h. The remaining steps and parameters are the same as in Example 1, and NiCoP / NF-100 is prepared.

[0046] Example 3: This embodiment is basically the same as Example 1, except that the hydrothermal reaction conditions in S1 are different. Specifically, the hydrothermal reaction temperature in S1 is 140℃ and the time is 4 h. The remaining steps and parameters are the same as in Example 1, and NiCoP / NF-140 is prepared.

[0047] Example 4: This embodiment is basically the same as Example 1, except that the low-temperature phosphating conditions in S2 are different. Specifically, the phosphating temperature in S2 is 300℃ and the time is 3 h. The remaining steps and parameters are the same as in Example 1, and NiCoP / NF-300 is prepared.

[0048] Example 5: This embodiment is basically the same as Example 1, except that the low-temperature phosphating conditions in S2 are different. Specifically, the phosphating temperature in S2 is 400℃ and the time is 1 h. The remaining steps and parameters are the same as in Example 1, and NiCoP / NF-400 is prepared.

[0049] Comparative Example 1: The preparation method for this comparative example is basically the same as that in Example 1, except that only nickel salt is added in S1, and cobalt salt is not added. Specifically, in S1, 0.872 g of nickel nitrate hexahydrate, 0.444 g of ammonium fluoride, and 1.802 g of urea are weighed and dissolved in 30 mL of deionized water. The remaining steps and parameters are the same as in Example 1, and a single metal phosphide comparative catalytic electrode, denoted as NiP / NF, is prepared.

[0050] Performance testing: 1. Microscopic morphological characterization: To evaluate the microstructure of the catalytic electrode prepared in this invention, the sample was characterized using a field emission scanning electron microscope (SEM, GeminiSEM 300, Zeiss, Germany) at an accelerating voltage of 5 kV.

[0051] like Figure 1 As shown, the nickel-cobalt bimetallic hydroxide precursor (NiCo-LDH / NF) prepared in Example 1 is uniformly loaded onto the surface of a nickel foam framework, exhibiting a spiky leaf-like structure composed of one-dimensional nanowires with a smooth surface. Figure 2 As shown, the NiCoP / NF (Example 1) obtained after low-temperature phosphating perfectly inherits the morphology of the precursor's spiky leaf-shaped nanowire array, and the nanowire surface becomes rough, which further increases the specific surface area and porosity.

[0052] 2. Phase and elemental composition analysis: like Figure 3 As shown, Ni, Co, and P elements are uniformly distributed on the surface of the nanowires.

[0053] The NiCoP / NF obtained in Example 1 was subjected to phase analysis using an X-ray diffractometer (XRD, Bruker D8 Advance, Germany), with a scanning range of 10°–80°. Figure 4 As shown, the diffraction peaks of the obtained NiCoP / NF catalytic electrode are in good agreement with those of the NiCoP / NF standard card (71-2336) and elemental nickel (04-0850), confirming the successful formation of nickel cobalt phosphide.

[0054] Elemental analysis of the sample from Example 1 was performed using energy-dispersive X-ray spectroscopy (EDS), such as... Figure 5 As shown, the presence of Ni, Co, and P elements on the catalyst surface was further confirmed.

[0055] 3. Electrochemical performance testing: All electrochemical tests were performed on a CHI760E electrochemical workstation (Shanghai Chenhua) using a standard three-electrode system. The prepared catalytic electrode (1 cm² area) was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. The electrolyte was either a 1.0 M KOH solution (for HER testing) or a 1.0 M KOH solution containing 0.1 M glycerol (for GOR testing). All potentials were expressed by the formula (E...). RHE = E Hg / HgO +0.098 +0.0591pH) are converted to potentials relative to the reversible hydrogen electrode (RHE). Linear sweep voltammetry (LSV) was performed at a scan rate of 5 mV / s with 85% iR compensation. Stability tests were conducted at constant potential using chronoamperometry.

[0056] (1) Hydrogen evolution reaction (HER) performance evaluation: Figure 6The HER polarization curves of Example 1 (NiCoP / NF), Comparative Example 1 (NiP / NF), and blank nickel foam in 1.0 M KOH electrolyte are shown. As can be seen from the figures, the synthesized NiCoP / NF catalytic electrode exhibits a higher current density and lower overpotential compared to the NiP / NF catalytic electrode and the blank nickel foam. At a current density of 10 mA / cm², the electrode achieves this. 2 At that time, the overpotential required for NiCoP / NF was only 116 mV, which was significantly lower than that of the control sample, indicating that it has excellent hydrogen evolution catalytic activity.

[0057] (2) Performance evaluation of glycerol oxidation reaction (GOR): like Figure 7 As shown, the NiCoP / NF catalytic electrode prepared in Example 1 exhibits excellent catalytic activity for GOR, with an onset potential of approximately 1.25 V vs. RHE, significantly lower than the onset potential of OER (approximately 1.47 V vs. RHE). At an applied potential of 1.30 V, this catalyst can achieve a flux of 10 mA / cm². 2 The current density of the NiCoP / NF electrode in a glycerol-containing electrolyte is much higher than that in a system without glycerol at the same potential, indicating that the glycerol oxidation reaction occurs effectively.

[0058] Figure 8 The image shows the Tafel slope plots of the NiCoP / NF electrode from Example 1 during the GOR and OER processes. The calculated Tafel slope for GOR is 42.6 mV / dec, significantly lower than the 132.8 mV / dec for OER. This result indicates that the glycerol oxidation reaction on the NiCoP / NF electrode exhibits more favorable reaction kinetics, which is the underlying reason why it can achieve high current densities at lower potentials.

[0059] (3) Stability assessment: Figure 9 The chronoamperometry curves for the NiCoP / NF electrode of Example 1 are shown in the chronoamperometry curves in a 1.0 M KOH electrolyte containing 0.1 M glycerol at a constant voltage of 1.35 V vs. RHE. It can be seen that after 10 hours of continuous electrolysis, the current density of the electrode hardly decays. Figure 9 The embedded inset shows a SEM image of the NiCoP / NF after testing, demonstrating that its spiny, leaf-like nanowire array structure remains intact without significant aggregation or collapse. This result fully demonstrates the excellent stability of the catalytic electrode prepared in this invention during the glycerol oxidation reaction.

[0060] (4) Analysis of bioactive species: To investigate the true active species of NiCoP / NF in the GOR process, in-situ Raman spectroscopy analysis was performed during the electrochemical testing. For example... Figure 10 As shown, when a potential of 1.50 V is applied to the electrode in a 1.0 M KOH solution, at 476 cm⁻¹... -1 and 555 cm -1 Two distinct Raman peaks appeared, which are attributed to the Ni-O vibrational mode of the NiOOH species. Upon addition of 0.1 M glycerol to the electrolyte, these two characteristic NiOOH peaks rapidly diminished and disappeared within 40 seconds. This dynamic process indicates that at high potential, the NiCoP / NF surface is first oxidized to generate the NiOOH active species; subsequently, this NiOOH species acts as a strong oxidant, rapidly oxidizing the glycerol molecules while being reduced back to the lower valence state of the Ni species. This cyclic process confirms that NiOOH is the true catalytic active center for the GOR reaction and reveals the microscopic mechanism by which the electrode material of this invention can efficiently catalyze the oxidation of glycerol.

[0061] 4. Study on the two-electrode coupled hydrogen evolution system Based on the excellent electrochemical performance of NiCoP / NF electrodes in GOR and HER, a dual-electrode alkaline electrolysis system with NiCoP / NF as both anode and cathode was constructed. The integrated hybrid water splitting system can simultaneously undergo glycerol oxidation at the anode and hydrogen production at the cathode. Figure 11 As shown, in the total water splitting system, 50 mA / cm² is provided at a battery voltage of 1.85 V. 2 The current density was [value missing]. After adding glycerol to the anode, the potential dropped significantly to 1.62 V at the same current density, demonstrating the advantage of the coupling strategy in reducing the voltage input of the hydrogen evolution system.

[0062] In summary, the NiCoP / NF spiny leaf-shaped nanowire array catalytic electrode prepared in this invention achieves highly efficient and stable bifunctional electrocatalysis for hydrogen evolution reaction and glycerol oxidation reaction through in-situ growth strategy and nickel-cobalt bimetallic synergistic effect, combined with a unique nanoarray structure, and has broad application prospects in the field of glycerol-assisted hydrogen production.

[0063] 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 method for preparing a nickel-cobalt phosphide catalytic electrode for glycerol oxidation, characterized in that, Includes the following steps: S1. Add nickel salt, cobalt salt, ammonium fluoride and urea to water and stir evenly, then carry out hydrothermal reaction with nickel foam substrate to obtain nickel cobalt bimetallic hydroxide precursor loaded on nickel foam. S2. The nickel-cobalt bimetallic hydroxide precursor loaded on nickel foam and sodium hypophosphite are placed in an inert atmosphere and subjected to low-temperature phosphating treatment to obtain the final product.

2. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S1, the mass ratio of nickel salt, cobalt salt, ammonium fluoride and urea is 0.8–1.2:0.8–1.2:1:3.5–4.

5.

3. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S1, the mass ratio of ammonium fluoride to the volume ratio of water is 0.444 g: 25-35 mL.

4. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S1, the nickel salt is nickel nitrate hexahydrate, and the cobalt salt is selected from cobalt nitrate hexahydrate.

5. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S1, the hydrothermal reaction temperature is 100–140℃ and the time is 4–8 hours.

6. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S2, the low-temperature phosphating temperature is 300-400℃, and the low-temperature phosphating time is 1-3h.

7. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S2, the heating rate during the low-temperature phosphating process is 2–5 °C / min.

8. The method for preparing the nickel-cobalt-phosphide catalytic electrode for glycerol oxidation as described in claim 1, characterized in that, In S2, the protective atmosphere is either high-purity argon or high-purity nitrogen, and the amount of sodium hypophosphite used is 0.1-1g.

9. A nickel-cobalt phosphide catalytic electrode for glycerol oxidation prepared by the method of any one of claims 1 to 8.

10. The application of the nickel-cobalt phosphide catalytic electrode for glycerol oxidation prepared by the preparation method according to any one of claims 1 to 8, or the nickel-cobalt phosphide catalytic electrode for glycerol oxidation according to claim 9, in glycerol-assisted hydrogen production.

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