Graphene-Dot Wrapped PtMo Nanosponge As a Highly Efficient Electrocatalyst for Hydrogen Evolution Reactions in Both Acidic and Alkaline Media

Abstract

A three-dimensional PtMo nanosponge wrapped with ultra-thin layers of graphene dots (denoted as 3D PtxMo1-x@graphene) has been developed for catalysis of the hydrogen evolution reaction (HER). The graphene-dot wrapping carries out by exfoliating carbon dots during the co-reduction of Pt and Mo precursors at a low temperature in an aqueous solution. The outstanding HER performance and superb durability, in both acidic and alkaline electrolytes, are attributed to the synergistic effects of inner metallic alloy networks and outer graphene dots in the 3D PtxMo1-x@graphene. The 3D PtxMo1-x@graphene reveals a low Tafel slope together with a low overpotential to produce a current density of -10 mA cm-2 in acidic media. Especially, the 3D PtxMo1-x@graphene catalyst overcomes a large amount of repeated potential cycling exceeding 5000 cycles in acidic solution and long-term durability of over 50,000 seconds in an alkaline solution. This work addresses a new feasible approach of synthesis of graphene-dot-wrapped Pt-based nanostructures with highly efficient catalytic activity and superior stability for HER without using surfactants or stabilizers.