Constructing Pure Phase Tungsten-Based Bimetallic Carbide Nanosheet as an Efficient Bifunctional Electrocatalyst for Overall Water Splitting

Carbides are commonly regarded as efficient hydrogen evolution reaction (HER) catalysts, but their poor oxygen evolution reaction (OER) catalytic activities seriously limit their practical application in overall water splitting. Here, vertically aligned porous cobalt tungsten carbide nanosheet embedded in N-doped carbon matrix (Co₆ W₆ C@NC) is successfully constructed on flexible carbon cloth (CC) as an efficient bifunctional electrocatalyst for overall water splitting via a facile metal-organic framework (MOF) derived method. The synergistic effect of Co and W atoms effectively tailors the electron state of carbide, optimizing the hydrogen-binding energy. Thus Co₆ W₆ C@NC shows an enhanced HER performance with an overpotential of 59 mV at a current density of -10 mA cm^-2 . Besides, Co₆ W₆ C@NC easily in situ transforms into tungsten actived cobalt oxide/hydroxide during the OER process, serving as OER active species, which provides an excellent OER activity with an overpotential of 286 mV at a current density of -10 mA cm^-2 . The water splitting device, by applying Co₆ W₆ C@NC as both the cathode and anode, requires a low cell voltage of 1.585 V at 10 mA cm^-2 with the great stability in alkaline solution. This work provides a feasible strategy to fabricate bimetallic carbides and explores their possibility as bifunctional catalysts toward overall water splitting.