Study on Electron Structure for Ni Base Amorphous Alloy Electrodes

A study of the electron structure of nickel base amorphous alloys have been made to explains the difference of the catalytic activity for the hydrogen evolution reaction(HER) between Ni-P amorphous alloys and Ni-Ce-P or Ni-La-P amorphous alloys.These alloy layers all were prepared on copper foil by an electrodeposition with the same condition,based on a series of experiments on the hydrogen evolution overpotential and X-ray photoelectron spectra(XPS),the hydrogen evolution overpotential ηH2,the orbital binding energy and Fermi energy level energy of individual element in amorphous alloys Ni-P,Ni-Ce-P and Ni-La-P were all recorded. From these measured results,some interesting conclusions have been shown as follows:①.The change tendency of the hydrogen evolution overpotential is consistent with that of the binding energy of Ni2p3/2 and P2p in above mentioned three alloys.As the binding energies deflct to low,the values of the hydrogen evolution overpotential ηH2 will decreased.Charge transfer from low electronegativity element to high electronegativity element occurs among atoms,the excess electrons are located near those high electronegativity element atoms.In the case,these excess electrons promote proton discharge and provide preferable sites for hydrogen evolution reaction.As the result,the value of the hydrogen evolution overpotential will decrease,and exhibited similarly charge tendency with the binding energy.②The Fermi energy level is also shown to be correlated with the hydrogen evolution overpotential.It is similar to①that the value hydrogen evolution overpotential decrease when the Fermi energy level energies increase.Since Fermi energy level is presentation of the electronic chemical potential,as the energy Fermi energy level is higher,the work function is less,then the electron on the alloy surface can more freely tranfer to proton,result in the value of the hydrogen evolution overpotential decrease.③.In addition,it can be seen that some hydrogen was storaged as CeH2 or LaH2 model in Ni-Ce-P or Ni-La-P amorphous alloys from the photoelectron spectra of Ce3d or La3d.Consequently,we have a suggestion that a storaging hydrogen effect possibly take place with Ceriam or Lanthanium in Ni-Ce-Por Ni-La-P amorphous alloys.