Self Supported Nitrogen Doped Ni₂P/SSM Nanosheet Array Catalyst For Application Of Electrolyzing Water

Electrocatalytic water decomposition is a simple chemical method to meet the energy demand in the future,which is highly efficient and sustainable to produce the highly pure and pollution-free hydrogen and can solve the intermittent problem of renewable energy.The hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)play an important role in the electrocatalytic water decomposition,which requires the electrocatalyst to have a rapid actual reaction rate.However,in practical applications,slow kinetics and large overpotential limit the two reactions.At present,TMPs have better conductivity than other metal oxides.In addition,TMPs with suitable d-electronic structure and excellent activity have been widely used in the application of bifunctional electrocatalysts.And their electrocatalytic properties and stability need to be further improved.The Ni2P/SSM catalyst was prepared by hydrothermal method.The results of SEM and EDS showed that the Ni and P elements were evenly distributed on the surface of the catalyst and the microstructure of the catalyst retained the morphology of the precursor and with more porous.The results of electrochemical test show that the best reaction conditions are annealing temperature of 300? and holding time of 1 h.In OER,when the current density reached at 100 m A·cm-2,the overpotential is only 1.58 V,and the Tafel slope is 55.7 m V·dec-1.And in HER,when the current density reached at 10 m A·cm-2,the overpotential is 0.12 V and the Tafel slope is 114.77 m V·dec-1.For electrolytic water,when the current density is up to 10 m A·cm-2,the overpotential is 1.61 V,which has a good performance of electrolyzing water.In order to further improve the electrocatalytic performance of the catalyst,through the heteroatom doping strategy,the self-supporting Ni2 P nano sheet array(N-Ni2P/SSM)material was prepared by doping nitrogen into the self-supporting Ni2 P nano sheet array material.The N-Ni2P/SSM catalyst showed excellent electrocatalytic performance for OER and HER in alkaline medium.In OER reaction,when the current density reached at 100 m A·cm-2,the over potential is only 1.56 V.And for HER reaction,when the current density reached 10 m A·cm-2,the over potential is only 0.10 V.N has stronger electronegativity than P,after nitrogen doping,leading to the doped nitrogen can reduce the electronic density of Ni and form hydrogen bond with intermediate products easily to reduce Gibbs free energy in OER.And in HER,the binding strength of H is weakened by the absorption of additional electrons from neighboring metal(Ni)atoms by N-substituted P.