A study on pulse plating amorphous Ni–Mo alloy coating used as HER cathode in alkaline medium

The amorphous Ni–Mo film with high HER (hydrogen evolution reaction) activity was obtained by pulse plating. The optimum electrodeposition conditions with respect to HER overpotential were determined, e.g. Na2MoO4·2H2O concentration, current density and duty cycle. Correspondingly, the compositions and components of the Ni–Mo coatings with various molybdenum contents were investigated systematically. The results showed that when the ratio of nickel and molybdenum concentrations in the electrodeposition bath is lower than 1 (mol%), the molybdenum content in the coating decreases with the increasing Na2MoO4·2H2O concentration, while the corresponding HER overpotential of the Ni–Mo film increases. The amorphous Ni–Mo coating was obtained when the molybdenum content was c.a. 30 mass%, which shows high HER activity (η200 = 62 mV at 200 mA cm−2 and 80 °C) and excellent corrosion resistance. After galvano-static electrolysis for 100 h in 33 mass% NaOH solution, the amorphous structure was destroyed due to the dissolution of molybdenum.