Structure and electrocatalytic hydrogen evolution performance of Mo2C thin films prepared by magnetron sputtering

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Mo2C, which has a unique electronic structure similar to the electronic structure of Pt, is considered as the material with the greatest potential to replace Pt as a catalyst for the electrocatalytic hydrogen evolution reaction (HER). However, Mo2C thin films have not attracted enough attention in the field of electrocatalysis. This work proposes a method for preparing Mo2C thin films as a catalyst for electrocatalytic HER through radiofrequency magnetron sputtering. The HER activity of the Mo2C thin film in acidic and alkaline media is studied by changing the deposition power of the Mo2C target and doping Ni for structural modification. Results show that increasing the deposition power of Mo2C can significantly enhance the HER activity of the films in acidic and alkaline media, and metal Ni doping can further enhance the HER activity of the Mo2C films. In an alkaline environment at a current density of 10 mA cm−2, the films demonstrate an overpotential of as low as 163 mV with a Tafel slope of 107 mV·dec−1. In acidic media, the films present the corresponding overpotential of 201 mV and a Tafel slope of as low as 96 mV·dec−1. Moreover, the Ni-doped Mo2C films have excellent HER stability. The synergy between doped Ni and Mo vacancies optimizes the strength of the Mo–H bond and the adsorption and desorption equilibrium of active H, thus enhancing HER kinetics. This work guides the possible structural design of Mo2C thin films for electrocatalytic HER.