Facile electrochemical synthesis of Ni(OH)2/MoSx catalyst on oxidized carbon fiber for efficient alkaline hydrogen evolution reaction.

• Synergy between Ni(OH) 2 and MoS x (MoS x : amorphous molybdenum sulfide) catalysts promotes alkaline HER performance. • Electrodeposition of Ni(OH) 2 and MoS x inspires facile approach for catalyst synthesis. • Oxidized carbon fiber provides hydrophilic substrate in favor of uniform electrodeposition in aqueous media. The efficient electrochemical hydrogen evolution reaction in alkaline media through the use of earth-abundant catalysts has received significant attention, as it is a crucial means for sustainable H 2 production. Here, we present a facile synthesis approach for Ni(OH) 2 /MoS x (MoS x : amorphous molybdenum sulfide) catalyst on oxidized carbon fiber support. Carbon fibers are first oxidized by a hydrothermal treatment in a concentrated HNO 3 solution, while Ni(OH) 2 and MoS x films are consecutively deposited onto the substrate through simple electro-deposition methods from their plating solutions. Benefiting from the hydrophilicity of the oxidized carbon fiber, the abundant electrochemically reactive sites and the synergistic effect between Ni(OH) 2 and MoS x , this hybrid catalyst shows a low HER onset potential of 80 mV at 1 mA/cm2, an overpotential of 180 mV at 10 mA/cm2 and a remarkable stability of at least 35 working hours at a H 2 -evolving current density of 10 mA/cm2 without any obvious overpotential changes. [ABSTRACT FROM AUTHOR]