Pyrolytic carbon supported alloying metal dichalcogenides as free-standing electrodes for efficient hydrogen evolution

Electrochemical reduction of water is a renewable way to produce clean hydrogen energy. In order to overcome the high-cost and shortage of noble metals, transition metal compounds involving earth-abundant elements, such as MoS₂ and WS₂, have been proposed as novel catalysts for hydrogen evolution reaction (HER). Efforts have been made to increase the intrinsic catalytic activity of transition metal dichalcogenides (TMDCs), while alloying same- group elements has not been vastly investigated. Moreover, besides the catalytic activity, the design of free-standing catalytic electrodes is also critical for HER. In this work, we synthesize pyrolytic carbon film with Mo_xW_1-xS₂ nanoflakes embedded as a free-standing flexible electrodes for HER catalysis. The pyrolytic carbon acts as conductive and flexible matrix for TMDC alloys with controlled composition, resulting in remarkably enhanced HER activity. The highest HER activity was observed for Mo_0.37W_0.63S₂/C samples with an overpotential of 0.137 V at geometric current densities of j_geo = 10 mA cm⁻² and a Tafel slope of 53 mV dec⁻¹. These results now provide low-cost viable alternatives for the design and construction of catalysts based on alloyed TMDCs.