Defect-rich NiFe Sulfide And Its Application In OER

Applied of fossil fuels lead to lack of energy and environment problems and the development of clean energy sources such as hydrogen and electric become a top priority.The oxygen evolution reaction with many steps is the bigger obstacle in the applied of electrocatalytic water splitting for hydrogen evolution and fuel-cell reactions.So finding a excellent catalytic performance and low cost catalyst to minimize the activation energy of the oxygen evolution reaction（OER）becomes a hot spot now.Due to the advantages of the sulfide of teansition metal and its layered double hydroxides（LDHs）,for examples,more active sites on the surface,well catalytic performance,high electrical conductivity,good stability,low cost and wide range of raw materials,its can get further application and development in catalysis and electrical storage.And inducing cation defects in catalytic material can improve its OER performance effectively.As follows:（1）MⅡcation defects could be induced by（NH₄）₂SO₄solution etched which have weak acidity after Ni Fe Mg-LDHs vulcanized.Its could be produced because of instability of Mg S in hot water and difference of Ksp value.Mg（OH）₂phase structure in Ni Fe sulfide could be eliminated after acid eached.Defect-rich Ni Fe S catalytic materials can be obtained by doping with different acid eached times in（NH₄）₂SO₄solution and promote its OER performance.The experimental results show that the defect-rich Ni Fe S material doped with a certain time can effectively construct cation defects and improve its OER catalytic ability.The overpotential of defect-rich Ni Fe S is only 253.3 m V at 10 m A cm^-2,and the Tafel slope is 62.83 m V dec^-1,which is better than that of the catalytic material under the same preparation conditions,which of the overpotential is 273.3 m V at 10 m A cm^-2,and the Tafel slope is 70.35 m V dec^-1.The catalytic material under the conditions;it can maintain a stable current density in the24-hour continuous voltage test,and has good stability.Defect structures can improve its OER performance by changing its phase structure and abjusting the valence states and bond structures of metal elements,its can lead to lower bond energy to minimize the activation energy of the oxygen evolution reaction and improve OER performance of catalytic material.（2）Defect-rich Ni Fe S catalytic materials can be obtained by doping with different contents of Al elements and etching in hydrothermal sulfidation.Defect structure can improve the OER activity of the catalytic material by adjusting the valence bond structure on the surface of the catalyst and improving the electrical conductivity of the catalytic material.The experimental results show that the defect-rich Ni Fe S material doped with a certain Al content can effectively construct cation defects and improve its OER catalytic ability.The overpotential of defect-rich Ni Fe S is only 253.3 m V at 10m A cm^-2,and the Tafel slope is 62.83 m V dec^-1,which is better than that of the catalytic material under the same preparation conditions,which of the overpotential is 273.3 m V at 10 m A cm^-2,and the Tafel slope is 70.35 m V dec^-1.The catalytic material under the conditions;it can maintain a stable current density in the 24-hour continuous voltage test,and has good stability.Defect structures can improve its OER performance by changing its phase structure and abjusting the valence states and bond structures of metal elements,its can lead to lower bond energy to minimize the activation energy of the oxygen evolution reaction and improve OER performance of catalytic material.This study illustrates the extent to which the defect structure can improve the performance of catalytic materials and finds a simple and effective construction method,which provides ideas for improving the performance of oxygen evolution catalysts and realizing high-efficiency electrolytic hydrogen production.Due to its advantages such as low costs,wide range of raw materials,simple manufacturing process,excellent catalytic performance and good stable,defect-rich Ni Fe sulfide will have wide application in industrialized electrocatalytic water splitting for hydrogen evolution and fuel-cell reactions.