Molybdenum oxide and molybdenum carbide coated carbon black as an electrocatalyst for hydrogen evolution reaction in acidic media

Molybdenum oxide and molybdenum carbide coated carbon black (MoO2-Mo2C/C) non-noble metal hybrid electrocatalyst for hydrogen evolution reaction (HER) was synthesized from a mixture of metal molybdenum (Mo) powders and carbon black particles by a spark plasma coating (SPC) method. After the SPC process, the MoO2-Mo2C coating can anchor strongly on carbon black with the help of intermediate products Mo2C. The MoO2-Mo2C/C electrocatalyst exhibited a good HER performance with an onset overpotential of −121 mV, a high exchange current density of 6.8 × 10−2 mA cm−2 and a Tafel slope of −69 mV dec−1 in 0.5 M H2SO4 solution. In addition, the MoO2-Mo2C/C showed much higher stability than Pt/C (20 wt% Pt supported on Vulcan XC-72 carbon black) after 3000 cycles of accelerated durability tests. The enhanced electrocatalytic activity and stability of MoO2-Mo2C/C electrocatalyst toward HER may originate from the Mo2C active sites formed in the process of SPC, and the effectively anchoring effect of MoO2-Mo2C coating on carbon black.