Graphene dot armored PtMo nanosponge as a highly efficient and stable electrocatalyst for hydrogen evolution reactions in both acidic and alkaline media

A new type of three-dimensional PtMo nanosponge wrapped with graphene dots (abbreviated as 3D PtxMo1-x@ graphene) has been developed for catalyzing the hydrogen evolution reaction (HER). The graphene-dot wrapping takes place via the exfoliation of carbon dots during the co-reduction of Pt/Mo precursors and carbon dots at a low temperature in an aqueous solution. The synergistic effects of inner metallic alloy networks and outer graphene dots in the 3D PtxMo1-x@graphene are responsible for the outstanding HER performance and superb durability in both acidic and alkaline electrolytes. The 3D PtxMo1-x@ graphene shows a low Tafel slope of 32 mV/dec and 51 mV/dec together with a low overpotential of 32 mV and 97 mV at a current density of 10 mA cm(-2) in acidic and alkaline media, respectively. The catalyst also shows superb stability, as confirmed by 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 provides a new feasible mean of synthesizing graphene-dot-wrapped Pt-based nanostructures with highly efficient catalytic activity and superb stability for HER without the need for surfactants or stabilizers. (c) 2019 Elsevier Ltd. All rights reserved.