Regulation of Sulfur Atoms in MoS_x by Magneto‐Electrodeposition for Hydrogen Evolution Reaction

Abstract Compared with crystalline molybdenum sulfide (MoS₂) employed as an efficient hydrogen evolution reaction (HER) catalyst, amorphous MoS_x exhibits better activity. To synthesize amorphous MoS_x, electrodeposition serving as a convenient and time‐saving method is successfully applied. However, the loading mass is hindered by limited mass transfer efficiency and the available active sites require further improvement. Herein, magneto‐electrodeposition is developed to synthesize MoS_x with magnetic fields up to 9 T to investigate the effects of a magnetic field in the electrodeposition processing, as well as the induced electrochemical performance. Owing to the magneto‐hydrodynamic effect, the loading mass of MoS_x is obviously increased, and the terminal S²⁻ serving as the active site is enhanced. The optimized MoS_x catalyst delivers outstanding HER performance, achieving an overpotential of 50 mV at a current density of 10 mA cm⁻² and the corresponding Tafel slope of 59 mV dec⁻¹. The introduction of a magnetic field during the electrodeposition process will provide a novel route to prepare amorphous MoS_x with improved electrochemical performance.