Preparition And Oer Performance Of Co,Ni,Fe,W-based Metal Oxide Materials

The increasing global energy demand and environmental issues have stimulated research activities in the development of efficient systems for the conversion and storage of sustainable and renewable energy.Electrochemical water splitting offers an ideal way for the production the clean fuel hydrogen.Oxygen evolution reaction(OER)as the determing reaction plays a core role in the process.As a result,it is urgent to develop highly efficient OER electrocatalysts.In recent years,the researches mainly focus on the transition metal catalysts,but the OER activity and the stability need to be improved.The electrocatalysts should have the following advantages:intrinsic active site,modulated electron state,large contact surface with electrolyte,and fast electron transportation.Herein,we use two different Co,Ni,Fe,W-based metal oxides as active materials,that are,polyoxometalate containing CoNi(NiCo-POM)and Fe-doping CoWO4.For the former one,NiCo-POM has been deposited onto Ni foam electrode.The resulting composite shows an enlarged contact surface with electrolyte,fast electron transportation and good OER activity,and better stability.For the latter one,the electron state can be modilated by Fe-doping.And it is verified that Fe-doping can improve the OER activity.And we combine the Fe-doping CoWO4 with CNT to improve the conductivity and to offer a growth substrate.Therefore,the detailed researches are as following:1.By using a facile one step hydrothemal method,we combine NiCo-POM and Ni foam(NiCo-POM/Ni)and study the structure and electrocatalytic properties of the as-prepared NiCo-POM/Ni.Through hydrothemal method,NiCo-POM/Ni is successfully prepared.The NiCo-POM/Ni electrode is applied for OER,The system shows excellent performance for electrochemical oxygen evolution with low overpotentials of 360 mV at 10 mA cm-2,high faradaic efficiency(96 ± 5%)and a Tafel slope of 126 mV dec-1.The electrode can operate for prolonged periods of time under basic conditions without chemical or mechanical degradation,making it the first stable polyoxometalate OER system for use in alkaline water electrolysers.2.By using a one pot solvothermal synthesis strategy,we synthesize Co1-xFexW04-CNT with Fe doping ranging from 10%to 100%and investigate the structure and electrocatalytic properties.Application of Co1-xFexW04-CNT as OER electrocatalyst shows with an appropriate Fe doping,the Co0.5Fe0.5WO4-CNT shows the smallest overpotential of 290 mV at a current density of 10 mA cm-2 and the lowest Tafel slope of 42 mV dec-1.In controlled potential electrolysis(CPE)at ?=300 mV,the nanocomposite shows an extremely stable current density of 10 mA cm-2 for 10 h in 1 M KOH.