Construction Of Non-precious Metal(Fe,Co,Ni) Based Self-supported Electrode And Its Electrocatalytic Performance For Water Oxidation

As an efficient energy storage and conversion technique,electrocatalytic water splitting opens up a new avenue for addressing the energy crunch and contamination caused by the usage of fossil fuels.Nevertheless,because of the slow kinetics of the oxygen evolution reaction,a substantial overpotential is required to induce OER,limiting the energy conversion efficiency of electrocatalytic water splitting significantly.As a result,one of the most pressing research needs for electrocatalysis is the design of OER electrocatalysts with high activity and stability.At present,RuO₂/IrO₂catalysts have been proven to be effective electrocatalysts for OER,but their high cost,low resource retention and rather poor stability severely limit their industrial utilization on a broad scale.In recent years,non-noble metal（Fe,Co,Ni）oxides,hydroxides,sulfides,and other catalysts have demonstrated considerable application promise.However,significantly improving the catalytic activity of such materials in order to minimize or replace the expensive noble metal-based catalysts remains a significant problem.Based on this,this paper begins with material design and synthesis and progresses through micro-nano structure design,interface regulation,and heterostructure construction of Fe,Co,Ni-based catalysts to solve the problem of high overpotential and slow kinetics of this type of catalysts,and realize low-energy water splitting,providing an exploration idea for the future design and development of efficient non-noble metal OER catalysts.This paper’s precise research contents are as follows:（1）Constructing a hollow Co-Ni dual hydroxide array to enhance OER activity.Compared to single-metal（Co or Ni）based catalysts,bimetallic catalysts with dual active sites can greatly enhance OER performance due to the synergistic effect.In this paper,metal-organic frameworks（MOFs）nanomatrix was used as a self-sacrificing template,and a hollow Co-Ni dual hydroxide array（Ni/Co-DH）was grown on the surface of three-dimensional foam nickel by cation exchange method.By regulating the ratio of Co²⁺/Ni²⁺and inducing surface active species reconstruction,the oxidation of water was greatly accelerated.The results revealed that the Ni/Co-DH not only had a 3-dimensional hollow structure that was favorable for electrolyte ion exchange andO₂release,but also had high active sites that could reduce the energy barrier and high conductivity that was conducive to fast electron transfer.Most importantly,Ni/Co-DH catalyst could obtain high active OER sites through surface reconstruction during OER process.In alkaline solution,the Ni/Co-DH catalyst showed excellent electrocatalytic OER performance,only requiring 229 m V overpotential to achieve 10 m A cm^-2oxygen evolution current,with a corresponding Tafel slope of 86.6 m V dec^-1,and stability over 90 hours at 300 m V applied overpotential.In addition,when Ni/Co-DH was used as anode and commercial Pt/C catalyst as cathode in 1.0 M KOH,only 1.55V voltage was required to achieve 10 m A cm^-2current density.（2）Interface engineering promotes efficient and stable oxygen evolution reaction（OER）of Co-Ni sulfide.Due to the unsatisfactory catalytic activity of single-component catalysts,combining two or more catalytic materials to construct a heterostructure is an effective strategy to improve catalyst activity.In this paper,a self-supported heterostructure composed of Fe-Ni₃S₂and Ni（OH）₂was constructed on the surface of foam nickel by interface engineering strategy for efficient water splitting reaction.The Fe-Ni₃S₂/Ni（OH）₂heterostructure exhibited outstanding electrocatalytic OER performance,only requiring 202 m V overpotential to reach 10m A cm^-2oxygen evolution current,with a corresponding Tafel slope of only 50.6 m V dec^-1,and could work stably for more than 60 hours at 0.25 A cm^-2high current density in 1M KOH solution.More interestingly,only 1.55V voltage was needed to achieve 10 m A cm^-2current density when this heterostructure electrode and Pt/C were utilized as the anode and cathode respectively for the overall water splitting.A series of experiments and theoretical analysis confirmed the strong electron interaction between Fe-Ni₃S₂and Ni（OH）₂interfaces,which not only reduced the activation energy of OER,but also regulated the d-band center,further balancing the adsorption and desorption of oxygen intermediates,thus accelerating the OER process.Therefore,through reasonable interface engineering,low-cost Fe-Ni₃S₂/Ni（OH）₂could potentially replace precious metals for alkaline water oxidation.