Electrodeposition of Molybdenum from Water-in-Acetate Electrolytes

This paper reports a systematic study on the electrodeposition of metallic molybdenum from water-in-salt electrolytes containing superhigh concentrations of acetate. Cyclic voltammetry and DC deposition were carried out on rotating disk electrodes with various concentrations of CH 3 COOK and CH 3 COONH 4 to determine the effects of NH 4 + and K + on Mo deposition. A comparison was performed between CH 3 COOLi, CH 3 COONa, and CH 3 COOK to study the effects of different alkali metal cations. A synergistic effect was observed between K + and NH 4 + , where Mo deposition rate is enhanced in the presence of both cations. However, such synergistic effect was not observed between NH 4 + and other alkali cations. In addition, the impact of substrate on Mo deposition was also studied using Pt and Cu electrodes with different activity toward hydrogen evolution reaction. Electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystallographic structure, and metallic state of Mo in the electrodeposited films.