| With the increasing use of global energy,non-renewable energy such as fossil fuels will be increasingly exhausted and have a serious impact on the environment.The wide-spread use of hydrogen energy will bring us into the time of sustainable development,and the large-scale and cheap production of hydrogen is an important prerequisite for the development and utilization of hydrogen energy.Among the numerous hydrogen evolution methods,water electrolysis has obvious advantages because of its low equipment cost,high purity of hydrogen.There are abundant ocean resources in China.If the seawater could be used as electrolyte for hydrogen evolution reaction,the hydrogen energy would have expanse development prospect.At present,the preparation about the cathode material for hydrogen evolution from seawater electrolysis is mainly by electrodeposition.It mainly focuses on the development of electrode materials to improve electrocatalytic activity and reduce hydrogen evolution overpotential.This paper aims to explore the nickel alloy cathodes for hydrogen evolution reaction from seawater electrolysis by powder metallurgy.In this paper,powders were used as raw materials such as Ni,Fe,Cu,Cr,etc.A series of binary,ternary and quaternary nickel alloy porous cathodes were designed and fabricated by reactive powder synthesis method:Ni-Fe,Ni-Cu,Ni-Fe-Mo-Cu,Ni-Cr-Mo-Cu,Ni-Cr-Fe,Ni-Fe-Mo,Ni-Fe-C and Ni-Ti.Scanning electron microscope,X-ray diffraction and back-scatter electron diffraction were used to characterize the surface morphology and phase composition of the electrode materials.The electrocatalytic performance,stability and corrosion resistance were analyzed by electrochemical methods such as cathodic polarization curve,cyclic voltammetry curve,impedance spectroscopy techniques,etc.The research work gets the following results:Ni-Fe,Ni-Cu,Ni-Fe-Mo-Cu and Ni-Cr-Mo-Cu are not suitable to be cathode materials for hydrogen evolution from seawater electrolysis.On the one hand,after the cathodic polarization tests,the four different kinds of porous electrodes show varying degrees of corrosion.For Ni-Fe alloy,the artificial seawater turns light yellow green after test,the surface of the sample is corroded and appears brownish red rust.The surface of the Ni-Cu alloy is corroded and copper rust appears.For Ni-Cr-Mo-Cu alloy,the seawater solution turns black after test.On the other hand,according to the cathodic polarization curves,these alloys show lower catalytic activity of hydrogen evolution in artificial seawater.When the cathode potential value is-1.5V,the current density value of Ni-Cu alloy is 173.01m A cm-2,the current density value of Ni-Fe-Mo-Cu alloy is95.73m A cm-2.Ni-Cr-Fe,Ni-Fe-Mo,Ni-Fe-C and Ni-Ti porous alloys,prepared by reactive powder synthesis method,are suitable to be cathode materials.All of them have interconnected and abundant pores.The Ni-Cr-Fe porous alloy is mainly composed of（Ni,Cr,Fe）solid solution matrix.Ni-Fe-Mo porous alloy is dominated by the Ni Fe Mo solid solution.Ni-Fe-C porous alloy has uniform composition and is composed of the diffusion of Ni3Fe and C.Ni Ti austenitic phase is dominant in porous Ni-Ti alloy.Compared with the four kinds of porous materials,Ni-Cr-Fe has better electrocatalytic performance,stability and corrosion resistance than the others.Ni-Cr-Fe electrodes sintered at 850℃exhibit the best activity with a low Tafel slope(-201.5m V dec-1).The apparent energy of activation has been calculated to be 27.57k J mol-1.Ni-Cr-Fe electrodes possess the smallest current decay（33.17%）after 500 cycles,higher corrosion potential（-0.19172V）,lower corrosion current(8.8412×10-8A cm-2)and lower corrosion rate(0.0010399mm y-1)than the other three kinds of electrodes. |
