Preparation Mo₂C Magnetron Sputtering Film Structure And Electrical Performance Study Of Catalytic Activity Of Hydrogen Evolution

Hydrogen is a clean energy source with high energy density and is considered the most promising alternative to traditional energy sources.Electrocatalytic hydrogen evolution（HER）is an ideal hydrogen production process,but Pt-type precious metal catalysts are expensive,so it is necessary to develop low-cost new HER catalysts.Molybdenum carbide（Mo₂C）,which has a unique electronic structure similar to the electronic construction of Pt,is considered the material with great potential to replace Pt as catalysts for HER.We use RF magnetron sputtering to prepare Mo₂C films.The influences of differential process parameters on the optical properties and electrocatalytic hydrogen evolution properties of Mo₂C films were studied.The films were modified by Ni doping to analyze the influence of Ni doping on the catalytic activity of Mo₂C films.（1）Mo₂C films with different structures were prepared by changing the CH₄ flow rate and were annealed at 850℃to study the structure and optical properties of Mo₂C films.The results indicate that the prepared Mo₂C thin films exhibit semiconductor properties,and the optical bandgap decreases with the increase of the CH₄ flow rate.After annealing at 850℃,the Mo₂C recrystallization of the（002）crystal surface and the crystallinity of the film was significantly increased.At the same time,the PL emission intensity of Mo₂C film decreases with the increase in the CH₄ flow rate because the ratio of sp²/sp³ is regulated by the CH₄ flow rate.（2）Mo₂C thin films with different Mo/C ratios were prepared by adjusting the RF power of Mo and C targets.Study the structure and electrocatalytic hydrogen evolution performance of thin films.These Mo₂C films show good catalytic activity in alkaline and acidic media.For Mo and C（power:200 W and 150 W）in an alkaline medium,the overpotential of 10 m A·cm^-2current density is 190 m V,the slope of Tafel is only 86m V·dec^-1,and the highest electrochemically active surface area is 80 F·cm^-1.The enhanced catalytic activity was attributed to the improved charge transfer ability of the more rational Mo/C atom structure.（3）Mo₂C thin films were prepared by changing the RF power of Mo₂C targets.Study the effects of different power levels on the electrocatalytic hydrogen evolution performance.The results indicate that these thin film catalysts exhibit excellent electrocatalytic performance in acidic and alkaline media.Among them,Mo₂C film with 250 W has 190 m V overpotential with a current density of 10 m A·cm^-2and a Tafel slope of 111 m V·dec^-1 in an alkaline medium.The higher Mo/C atom ratio of the Mo₂C crystal structure was obtained by high-power sputtering,which enhanced the electron transport and charge transfer ability.（4）Mo₂C films were modified by 0.5,1,and 2Ni doping to study the effect of Ni doping on electrocatalytic hydrogen evolution performance of Mo₂C films.The results indicate that the appropriate amount of Ni-doped Mo₂C thin films showed significantly enhanced HER activity in both acidic and alkaline media.The current density is 10m A·cm^-2 of the 1 Ni-Mo₂C film in an acidic medium,the overpotential is 201 m V,and the slope of Tafel is as low as 96 m V·dec^-1.In alkaline,the corresponding overpotential is as low as 163 m V,and the Tafel slope is 107 m V·dec^-1.The corresponding overpotential of 2 Ni-Mo₂C in alkaline medium is as low as 155 m V.The Ni-doped Mo₂C film has excellent electrochemistry stability.The strength of the Mo-H bond is optimized by Ni-doped adjustment of the electronic structure of Mo₂C and the synergistic effect of vacancy in Mo₂C,thus enhancing HER kinetics.