Highly Active Cobalt/Tungsten Carbide@N‐Doped Porous Carbon Nanomaterials Derived from Metal‐Organic Frameworks as Bifunctional Catalysts for Overall Water Splitting

Currently, the design and application of low‐cost and highly active bifunctional electrocatalysts for oxygen evolution reactions (OERs) and hydrogen evolution reactions (HERs) are still challenging. Metal‐organic frameworks (MOFs) are used to produce a material composed of porous nitrogen‐doped carbon materials encapsulating cobalt and tungsten carbide (Co/W‐C@NCNSs). Nanoscale MOFs are successfully synthesized via a microwave method and are denoted as HZIF‐W. Moreover, the obtained MOFs are annealed under N 2 atmosphere at a temperature of 600 and 800 °C, and the obtained samples are designated as Co/W‐C@NCNSs(600) and Co/W‐C@NCNSs(800), respectively, according to the annealing temperature. The results show that the obtained Co/W‐C@NCNSs exhibit superior performance toward both the OER and HER in alkaline media. Co/W‐C@NCNSs(800) shows the best electrocatalytic activities, requiring an overpotential of 323 mV (vs RHE) and −252 mV (vs RHE) to achieve a current density of 10 mA cm −2 for the electrocatalytic OER and HER in an aqueous solution. A water electrolyzer device using Co/W‐C@NCNSs(800) as both the anode and cathode requires only a cell voltage of 1.68 V to reach a current density of 10 mA cm −2 , thus illustrating that cobalt/tungsten carbide‐based NCNSs derived from MOFs can be prospective materials for the electrocatalysis of water splitting.