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CN-121976236-A - Preparation method of low-overpotential OER anode catalyst

CN121976236ACN 121976236 ACN121976236 ACN 121976236ACN-121976236-A

Abstract

The invention relates to the technical field of electrocatalytic materials, and discloses a preparation method of a low overpotential OER anode catalyst, which comprises the following steps of A, placing a foam nickel substrate in a dilute hydrochloric acid solution for pickling treatment to remove a surface oxide layer, then ultrasonically cleaning in deionized water and drying in a vacuum oven to obtain a pretreated conductive substrate, and B, preparing a multi-element metal salt solution containing nickel salt, iron salt, cobalt salt, manganese salt and cerium salt, wherein the molar ratio of the nickel salt to the iron salt to the cobalt salt to the manganese salt to the cerium salt is (3-5): (2-4): (1-3): (0.5-2): (0.2-1). The high-entropy spinel oxide and carbon composite nano-sheet array rich in oxygen vacancies is constructed on the surface of a conductive substrate by combining multielement metal salt solution constant current electrodeposition with millisecond-level Joule heating defect engineering, and the central position of a catalyst d zone is regulated and controlled by anion in-situ doping, so that the adsorption and desorption energy barriers of an oxygen-containing intermediate are cooperatively optimized, and the over-potential of an oxygen evolution reaction is obviously reduced.

Inventors

  • Li daiyue

Assignees

  • 南京师范大学

Dates

Publication Date
20260505
Application Date
20260203

Claims (10)

  1. 1. A method for preparing a low overpotential OER anode catalyst, comprising the steps of: step A, placing a foam nickel substrate in a dilute hydrochloric acid solution for acid washing treatment to remove a surface oxide layer, and then ultrasonically cleaning in deionized water and drying in a vacuum oven to obtain a pretreated conductive substrate; And (B) step (B): preparing a multi-element metal salt solution containing nickel salt, ferric salt, cobalt salt, manganese salt and cerium salt, wherein the molar ratio of the nickel salt to the ferric salt to the cobalt salt to the manganese salt to the cerium salt is (3-5), (2-4), (1-3), (0.5-2), (0.2-1), and the solvent is formed by mixing deionized water and ethylene glycol according to the volume ratio of 1 (0.5-2) and stirring fully to form a homogeneous precursor solution; Step C, constructing a three-electrode system by taking the pretreated conductive substrate as a working electrode, a graphite rod as a counter electrode and a saturated calomel electrode as a reference electrode, performing constant current electrodeposition in the homogeneous precursor solution, setting the current density to be-10 to-50 mA/cm < 2 >, and enabling the deposition time to be 300 to 900 seconds, and growing an amorphous multi-element metal hydroxide nano-sheet array on the surface of the conductive substrate in situ; Transferring the conductive substrate deposited with the amorphous multi-element metal hydroxide nano-sheet array into N, N-dimethylformamide solution containing organic ligand, wherein the organic ligand is at least one of terephthalic acid, trimesic acid or 2-amino terephthalic acid, and performing solvothermal reaction for 6-12 hours at 120-150 ℃ to enable a metal organic framework to grow epitaxially on the surface of the amorphous multi-element metal hydroxide to form a core-shell precursor composite material; e, placing the core-shell type precursor composite material in a Joule heating device, under the protection of argon atmosphere, applying pulse direct current to heat a sample to 800-1000 ℃ within 10-100 milliseconds, rapidly cooling to room temperature after the heat preservation time is 50-200 milliseconds, and introducing oxygen vacancy defects and lattice distortion into the high-entropy alloy oxide lattice through millisecond-level Joule heating to obtain a high-entropy spinel oxide/carbon composite nano-sheet array rich in defects; step F, preparing an anion source solution containing thiourea, selenourea or sodium hypophosphite, immersing the defect-rich high-entropy spinel oxide/carbon composite nano-sheet array into the anion source solution, and performing hydrothermal reaction at 160-200 ℃ for 2-4 hours to enable sulfur, selenium or phosphorus anions to be doped into the high-entropy spinel oxide crystal lattice in situ, and regulating and controlling the center position of d bands to obtain an anion doped high-entropy oxide catalytic material; Adopting an atomic layer deposition technology, taking bis (cyclopentadienyl) ruthenium or iridium acetylacetonate as a precursor, and selectively anchoring metal monoatoms/clusters of ruthenium or iridium on the oxygen vacancy defect sites on the surface of the anion doped high-entropy oxide catalytic material at 200-300 ℃ to form synergistic active sites of the metal monoatoms/clusters and the anion doped high-entropy oxide; And H, placing the material subjected to the atomic layer deposition treatment into a potassium hydroxide solution, performing 50-200 circles of cyclic activation at a scanning rate of 20-100mV/s in a potential range of 0-0.8Vvs. Hg/HgO by a cyclic voltammetry, and inducing surface reconstruction to generate an amorphous hydroxyl oxide active layer to finally obtain the low overpotential OER anode catalyst.
  2. 2. The method for preparing the low overpotential OER anode catalyst according to claim 1, wherein in step B the nickel salt is selected from nickel nitrate, nickel chloride or nickel acetate, the iron salt is selected from iron nitrate, iron chloride or iron acetate, the cobalt salt is selected from cobalt nitrate, cobalt chloride or cobalt acetate, the manganese salt is selected from manganese nitrate, manganese chloride or manganese acetate, the cerium salt is selected from cerium nitrate or cerium chloride, and the total metal ion concentration of the multi-metal salt solution is 0.05 to 0.2mol/L.
  3. 3. The method of preparing a low overpotential OER anode catalyst according to claim 1, wherein in step D the molar ratio of the organic ligand to the metal ions in the amorphous multi-metal hydroxide is (1-3): 1, the temperature gradient of the solvothermal reaction is set to be raised to 80 ℃ at 5 ℃ per minute for 1 hour, and then raised to 120-150 ℃ at 3 ℃ per minute for 5-11 hours to promote lattice matching during the epitaxial growth.
  4. 4. The method for preparing the low overpotential OER anode catalyst according to claim 1, wherein the current density of the pulsed direct current in the step E is 100-500A/cm 2, the rapid cooling rate is 10 5 -10 6 K/s, and the concentration of the oxygen vacancy defects is controlled within a range of 5% -15% by adjusting the pulse width and the incubation time.
  5. 5. The method of preparing a low overpotential OER anode catalyst according to claim 1, characterized in that in step F the concentration of the anion source solution is 0.01-0.1 mol/L and when using the thiourea, the doping sulfur element forms NiFeCoMnCe-S active site, when using the selenourea, the doping selenium element forms NiFeCoMnCe-Se active site, when using the sodium hypophosphite, the doping phosphorus element forms NiFeCoMnCe-P active site, the anion doping content is 1-5at.%.
  6. 6. The method for preparing a low overpotential OER anode catalyst according to claim 1, wherein the number of cycles of atomic layer deposition in step G is set to 50-200, the deposition time is 0.5-2 seconds/cycle, the purge time is 10-30 seconds/cycle, the loading amount of ruthenium or iridium is 0.5-2wt.%, and the particle size of the metal monoatoms/clusters is controlled to be in the range of 0.5-2 nm.
  7. 7. The method of preparing a low overpotential OER anode catalyst according to claim 1, wherein the concentration of the potassium hydroxide solution in step H is 1-6 mol/L, and the concentration of the amorphous oxyhydroxide active layer formed in the process of cyclic activation is maintained at 0.4-0.6vvs.hg/HgO potential for 30-60 seconds to promote the formation of high valence metal state, and the thickness of the amorphous oxyhydroxide active layer formed in the process of cyclic activation is 2-5nm.
  8. 8. The process for preparing a low overpotential OER anode catalyst according to claim 1, characterized in that the foamed nickel substrate has a porosity of 80% -95%, a pore size of 50-500 μm, the concentration of the dilute hydrochloric acid solution in step a is 1-3 mol/L, the pickling treatment time is 10-30 minutes, the drying temperature of the vacuum oven is 60-80 ℃, and the drying time is 2-4 hours.
  9. 9. The process for preparing a low overpotential OER anode catalyst according to claim 1, characterized in that the overpotential required for the prepared low overpotential OER anode catalyst to reach a current density of 10mA/cm2 is 150-190mV in 1mol/L potassium hydroxide electrolyte, the tafel slope is 30-45mV/dec, and the increase of the overpotential is less than 5% after continuous operation for 1000 hours at a constant current density of 100mA/cm 2.
  10. 10. The method for preparing a low overpotential OER anode catalyst according to claim 1, characterized in that the low overpotential OER anode catalyst has a hierarchical porous structure comprising macro-porous channels provided by the foamed nickel substrate, a meso-porous structure formed by stacking the high entropy spinel oxide nano-sheets, and micro-porous defects generated by the anion doping, the hierarchical porous structure has a specific surface area of 80-150 m2/g, the nano-sheet array has a sheet thickness of 5-20nm, and a sheet spacing of 10-50nm.

Description

Preparation method of low-overpotential OER anode catalyst Technical Field The invention relates to the technical field of electrocatalytic materials, in particular to a preparation method of a low-overpotential OER anode catalyst. Background Along with the increasing severity of global energy crisis and environmental problems, the development of clean renewable energy and efficient conversion technology thereof has become a strategic consensus in all countries of the world. Hydrogen energy is regarded as a secondary energy carrier with high energy density and environmental friendliness and is regarded as a key component for constructing a future clean energy system. The technology of hydrogen production by water electrolysis, in particular to the green hydrogen production with zero carbon emission by utilizing the renewable energy driven water electrolysis process, thus receiving extensive attention from academia and industry. In the half reaction of an electrolytic water system, the oxygen evolution reaction relates to the four-electron transfer process and the formation of oxygen-oxygen bonds, has slow reaction dynamics and higher overpotential, and becomes a bottleneck for limiting the overall efficiency of hydrogen production by water electrolysis. In order to reduce the activation energy barrier of oxygen evolution reaction and energy loss, the development of a high-performance anode catalyst is important. Noble metal oxides such as ruthenium dioxide and iridium dioxide are currently considered as reference catalysts for oxygen evolution reactions due to their excellent catalytic activity and chemical stability. However, noble metal resources are scarce, expensive and are subject to dissolution and deactivation under long-term high-potential operating conditions, and it is difficult to meet the cost and durability requirements of large-scale industrial applications. In order to break through the cost limit of noble metal catalysts, transition metal nickel, iron, cobalt, manganese and compound-based catalysts thereof have become the key direction of current research due to abundant reserves, low cost and adjustable intrinsic activity. The nickel-iron layered double metal hydroxide and the derivative oxide thereof show catalytic potential close to that of noble metal, but have poor conductivity and insufficient exposure of active sites, so that high overpotential driving target current density is still required in practical application. In addition, the simple binary ferronickel system is easy to dissolve active phases and collapse crystal structures in the long-term electrolysis process, and the electrochemical stability is required to be improved. In terms of preparation technology, the prior art mainly adopts a hydrothermal method, a solvothermal method, an electrochemical deposition method and a high-temperature calcination method to construct the non-noble metal-based catalytic material. Although the hydrothermal method and the solvothermal method can realize the uniform growth of the nano structure, the reaction period is long, the energy consumption is high, and the active material is difficult to firmly anchor on the surface of the conductive substrate. The electrochemical deposition method can grow active materials on the surface of the conductive substrate in situ, and has good interfacial binding force, but the deposition process is difficult to accurately control the crystal orientation and defect concentration, and the obtained materials are often low in crystallinity and few in lattice defects, so that the improvement of the catalytic intrinsic activity is limited. The high-temperature calcination method is easy to cause agglomeration and sintering of nano particles, the specific surface area is reduced, and high-activity defect sites of the material can be damaged by long-time heat treatment. The catalyst obtained by the preparation method has the technical defects that firstly, the electronic structure regulation means of a material bulk phase and a surface are single, accurate optimization of oxygen-containing intermediate adsorption energy is difficult to realize, the overpotential of an oxygen evolution reaction is high, secondly, the charge transmission resistance between the catalyst and a conductive substrate is large, the construction of a conductive network of an active material is imperfect, the electrochemical reaction kinetics is slow, thirdly, under the conditions of high current density and long-term operation, the catalyst is easy to change phase, dissolve or peel off, the catalytic activity and the structural stability are difficult to be compatible, and fourthly, the maximization of the density of active sites and the utilization rate of atoms is difficult to be realized in the prior art, and the synergistic effect of a noble metal promoter and a transition metal substrate cannot be fully exerted. Therefore, development of a novel anode catalyst preparation method is need