Electrochemical Method To Prepare NiCoP And Ni/Fe Water Splitting Catalysts And Performance Research

Water splitting consists of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In order to increase the rate of catalytic reaction and decrease the overpotentials of HER and OER,many researches have focused on some trasition metals(such as Co,Ni,Fe,Mo)and some non-metallic elements(such as N,P,S,C).The compounds of these elements have been confirmed as the high active electrocatalysts for water splitting.Except the catalytic materials,a low cost and easily controlled synthetic technology is also significant.Therefore,this paper aimed at exploring an easy and mild method to fabricate a series of high efficient HER and OER catalysts.Herein,we used a simple potentiostatic electrodeposition method to fabricate highly dispersed NiCoP nanoparticles as an active HER electrode on carbon nanotubes modified Ni foam(CNT/NF).All the surface morphology and elementary composition of catalysts were analyzed by XRD,SEM and XPS during the research process.The results suggested that the hexagonal NiCoP showed a complex material with polyvalent interactions of Ni,Co and P heteroatoms,which contributes to form a nanoparticle structure and helps enhance the surface activity toward HER.Linear sweep voltammetry(LSV)was been used to analysis the catalytic performance of electrodes.The as-prepared NiCoP/CNT/NF electrode showed high activity towards HER,with an onset overpotential of 69 mV and a tafel slop of 62 mV dec-1 in 1 M KOH,an onset potential of 52 mV and a Tafel slope of 48 mV dec-1 in 0.5 M H2SO4,respectively.The results showed that NiCoP/CNT/NF could provide a promising way to fabricate robust catalysts as alternatives of the state-of-art noble metal.Furthermore,we anodized NiFe alloy and conducted the material by CV in 0.1 M KOH based on the research background of NiFe.NiFe alloy transformed into Ni/Fe fluoride at first,XRD and XPS confirmed the formation of triclinic NiFeF5·7H2O with NiⅡ and FeⅢ before CV treatment,and then turned into Ni/Fe hydroxide with NiⅢ and FeⅢ after CV treatment.The as-prepared Ni/Fe hydroxide showed a crack structure and much higer OER activity than untreated NiFe alloy,with an onset overpotential of 240 mV and a tafel slop of 47 mV dec-1 in 0.1 M KOH.We systematically analysed the reaction mechanism during the process of fabricating Ni/Fe hydroxide and provided experimental theoretical data for future electrochemical anodization method.