Co-WC Heterojunction Nanoparticle Composites with Graphene Embedded in Porous Carbon Nanospheres as an Electrocatalyst for the Hydrogen Evolution Reaction

Exploring high-performance, stable, and economical noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) in alkaline media is an urgent mission. Herein, the graphene-wrapped Co-WC heterojunction nanoparticle embedded in porous carbon nanospheres (Co-WC@G/PCSs) is fabricated via calcination of a CoWO4/PCSs precursor. With an optimized PCSs amount and carbonization temperature, sphere-like Co-WC@G/PCSs exhibit superior alkaline HER activity with a small overpotential (67 mV at a current density of 10 mA cm–2), a low Tafel slope (56 mV dec–1), and a high exchange current density (0.48 mA cm–2). Moreover, the Co-WC@G/PCSs also exhibit high stability in alkaline solution, showing no significant degradation after 10 000 cycles. The excellent HER performance is mainly attributed to abundant heterointerface interfaces between Co and WC, which can tailor the electronic configuration and enlarge exposed active sites. Our work suggests a facile and large-scale strategy to synthesize abundant heterointerface interfaces and graphene-coated electrocatalysts for designing an efficient noble-metal-free electrocatalyst.