Preparation And Performance Of Nickel-Ferric Selenides For Electrochemical Water Splitting Based On Prussian Blue Analogue Precursors

Due to the over-exploitation of fossil fuels,the energy crisis has become one of the most serious threats to human development.Therefore,developing environmentally friendly renewable energy has become an urgent matter.As a renewable energy,hydrogen has the characteristics of high energy density and free of pollution during use.It is a potential substitute for fossil fuels.Hydrogen production by electrolysis of water has the advantages of high availability,flexibility and purity.However,in order to achieve wide application,it is necessary to design efficient,low-cost and long-life electrocatalysts to promote the electrochemical reaction of cathode and anode in the process of electrolysis of water.In general,the common strategies for the design of highly active electrocatalysts include increasing specific surface area,ion doping,and constructing hybrid structures.Metal-organic Frameworks have become one of the research hotspots due to their porous structure,abundant active sites and adjustable chemical composition.As a low-cost MOF material,Prussian blue has attracted great attention from researchers.Based on the above considerations,this paper uses a simple electrodeposition process to prepare binary NiFe and ternary NiCoFe Prussian blue analogue（PBA）precursors on carbon fiber paper（CFP）,and further obtain the corresponding metal selenide electrocatalysts through gas-phase selenization,and its performance of water electrolysis in alkaline solution was systematically characterized.The main research contents and conclusions of this paper are as follows:（1）In the electrolyte containing Ni²⁺and[Fe（CN）⁶]^3-ions,NiFe PBA precursor nanoparticles with cubic structure were uniformly deposited on CFP by cyclic voltammetry.Then the gas phase selenization reaction was carried out,and the cubic NiFe-Se nanoparticles with mesoporous morphology were obtained by adjusting selenization temperature and selenium powder loading amount.In 1MKOH solution,NiFe-Se/CFP showed higher catalytic activity than the precursor NiFe PBA/CFP and the single-metal selenide FeSe₂/CFP.Only 214mV hydrogen evolution and 281mV oxygen evolution overpotential are needed to drive the current density of 10mAcm^-2,and the corresponding Tafel slope is 51.63mVdec^-1and 40.93mVdec^-1,respectively.As a bifunctional electrocatalyst,the current density of 10mAcm^-2 driven by NiFe-Se/CFP is only 1.55V.At the same time,NiFe-Se/CFP has good stability in alkaline solution.The excellent electrocatalytic activity was attributed to the synergistic effect of Ni and Fe and the large electrochemical active area,which enhanced the electrocatalytic activity of the electrocatalyst.（2）The NiCoFe-Se/CFP nanoparticle catalyst was prepared by gas phase selenization with ternary NiCoFe PBA/CFP as the precursor by adding Co²⁺into the Ni and Fe systems.In 1MKOH solution,by comparing the catalytic performance of monometallic and bimetallic selenide,it is found that NiCoFe-Se/CFP exhibits higher electrocatalytic activity,requiring only 154mV of hydrogen evolution and 221mV of oxygen evolution overpotential.It can drive to a current density of 10mAcm^-2,and the Tafel slopes are as low as 45.25mVdec^-1and 39.88mVdec^-1,respectively.As a bifunctional electrocatalyst,the current density of 10mAcm^-2 can be reached at 1.518V.Compared with binary metal Prussian blue precursors,the three-phase hybrid catalyst obtained by selenization of ternary metal Prussian blue precursors has higher electrocatalytic activity.This can be attributed to the synergistic effect between Ni-Co-Fe selenides.