Graphene-coated cobalt-based coordination polymers for efficient hydrogen evolution reaction catalysts in acidic media

A novel cobalt-based coordination polymer(CP) was synthesised, named [Co(H3L)(bimb)3(H2O)]n, and the complex was compounded with graphene oxide that was calcined at high temperature to form a composite material Co-CP-Go(omega%). Due to the synergistic effect of cobalt-based and graphene, Co-CP-Go(omega%) exhibited good hydrogen precipitation properties in acidic medium. When the content of graphene oxide was 4 %, Co-CPGo(4 %) showed the best electrocatalytic performance with an over-potential of 115 mV (vs. RHE) at 10 mA cm-2, a Tafel slope of 59 mV dec- 1 and good stability in 0.5 M H2SO4 solution. The catalyst is expected to be a good alternative for hydrogen evolution reaction(HER) applications compared to precious metal materials such as platinum-based metals.