Structure And Catalytic Properties Of Hydrogen Evolution Of NiMo Films Prepared By Magnetron Sputtering

Noble metal Pt is a commonly used hydrogen evolution catalyst in the production of hydrogen from electrolyzed water.However,due to the lack of Pt resources and the high price,it is urgent to develop a new hydrogen evolution catalyst without precious metals.Although Ni3 N,Mo S2 and other hydrogen evolution catalysts have been developed,their catalytic activity is still lower than that of Pt,and it is necessary to develop new hydrogen evolution catalyst with higher catalytic activity.Among the various electrolyzed hydrogen evolution catalysts reported,Ni-based and Mo-based catalysts have the most development potential.Ni(3d84s2)with double-d electron orbitals facilitates the migration of water molecules and the subsequent cleavage of O-H bonds,while Mo(4d55s1)with half-empty d-electron orbitals facilitates the formation of adsorbed hydrogen(Hads).Therefore,the NiMo hydrogen evolution catalyst is expected to reduce the energy barrier during the hydrogen evolution reaction(HER)process,accelerate the HER kinetics under alkaline conditions,and become a new hydrogen evolution catalyst that replaces the precious metal Pt.In this paper,the magnetron sputtering process is used to prepare NiMo thin films.The effect of magnetron sputtering process parameters on the film structure and catalytic performance of hydrogen evolution is first studied.It is controlled by N doping,reverse sputtering surface etching and Ar plasma surface etching technology to regulate membrane structure.The structure,surface morphology and composition of the film are mainly tested by X-ray diffraction analysis(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The catalytic performance of hydrogen evolution is tested by an electrochemical workstation.The controlled variable method was used to study the composition,structure,microstructure and catalytic properties of NiMo films under different magnetron sputtering process parameters,and to determine the preparation process of high-performance NiMo films.Ni20Mo80 thin film was obtained when the sputtering power ratio of Ni target:Mo target was 100W:200W,which consisted of two phases of NiMo and Mo.When the sputtering power ratio of Ni target:Mo target was 280W:55W,Ni80Mo20 thin film was obtained.It consists of a single Ni4 Mo phase.With the increase of the sputtering power ratio of Ni target:Mo target,the relative content of Ni in the film gradually increases,the grain size increases,and the catalytic performance of hydrogen evolution decreases.As the substrate temperature increases,the diffraction peak of the Ni20Mo80 film(041)shifts to the left and the half-width becomes smaller,the composition does not change significantly,the grain size increases and is more uniform,and the catalytic performance of hydrogen evolution decreases;Ni80Mo20 film(121)diffraction The peak shifted to the left and the half-width became smaller.There was no significant change in the composition.the grain size increases and is more uniform.The catalytic performance of hydrogen evolution increases first and then decreases.With the increase of the substrate bias,the diffraction peak of Ni20Mo80 film(041)shifts to the right and the half width becomes larger,the relative content of Ni in the film gradually decreases,the grain refinement and the surface roughness of the film decrease,and the catalytic performance of hydrogen evolution decreases;In the Ni80Mo20 film(121),the diffraction peak shifts to the left and the half-width becomes larger.The relative content of Ni in the film gradually decreases,the grain refinement and the film surface roughness decrease,and the the catalytic performance of hydrogen evolution decreases.Through the above research,the best process parameters of NiMo thin film prepared by magnetron sputtering: Ni target: Mo target power ratio of 100W:200W,substrate temperature of 298 K,substrate bias voltage of 0V,under these conditions prepared the Ni20Mo80 thin film has the most excellent catalytic performance of hydrogen evolution,the overpotential(?10)at a current density of 10 m A cm-2 is 150 m V,the slope of Tafel is 56 m V dec-1,and the load transfer resistance is 12?.In order to further improve the catalytic performance of hydrogen evolution of the Ni20Mo80 thin film prepared under the optimal magnetron sputtering process parameters,a controlled variable method was adopted to study the structure and the influence law of the catalytic performance of hydrogen evolution of Ni20Mo80 thin film by N element doping,reverse sputtering surface etching and Ar plasma surface etching,the structure control process of high performance Ni20Mo80 membrane was established.In the N-doping process,with the increase of the N2 partial pressure of magnetron sputtering,the relative content of Mo in the film decreases,the grain size gradually increases,and the catalytic performance of hydrogen evolution decreases.In the surface etching process of the reverse splash method,with the increase of the reverse splash power,the film composition did not change significantly,the grain size decreases first and then increases,and the catalytic performance of hydrogen evolution first increases and then decreases;with the increase of the reverse splash time,the film composition did not change significantly,the grain size decreases first and then increases,and the catalytic performance of hydrogen evolution first increases and then decreases.During the etching process of the Ar plasma surface,with the increase of the screen voltage,the diffraction peak of the Ni20Mo80 film(041)shifts to the right and the half-width becomes larger,the relative content of Ni in the film gradually decreases,the grain size decreases first and then increases,and the catalytic performance of hydrogen evolution increases first and then decreases;as the etching time increases,the diffraction peak ofNi20Mo80 film shifts to the right and the half-width becomes larger,the relative content of Ni in the film gradually decreases,the grain size decreases first and then increases,and the catalytic performance of hydrogen evolution increases first and then decreases.Through the above research,the best process parameters of Ni20Mo80 thin film structure and performance regulation were obtained: the Ni20Mo80 modified by the surface etching method of the back splash method with the back splash power of 100 W and the back splash time of 1min has the best catalytic performance,the overpotential(?10)at a current density of 10 m A cm-2 is 91 m V,the slope of Tafel is 41 m V dec-1,and the load transfer resistance is 5?.The catalytic performance of hydrogen evolution is better than Ni Se/Nifoam(96m V,120 m V dec-1)and Fe2Ni2N/Nifoam(180m V,120 m V dec-1)in literature,even better than the overpotential 125 m V of Pt foil at a current density of10 m A cm-2,ie The electrolysis of water can be achieved with a smaller decomposition voltage,and it is expected to become a new type of hydrogen evolution catalytic membrane to replace precious metal Pt.