Graphene-Quantum-Dots-induced facile growth of porous molybdenum doped Ni3S2 nanoflakes as efficient bifunctional electrocatalyst for overall water splitting

Abstract

Taking into account the development of carbon-neutral economy, exploring noble-metal-free electrocatalysts is still a great challenge for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through water splitting. Herein, Graphene-Quantum-Dots (GQDs) loaded and molybdenum doped porous Ni3S2 hybrid (G-Mo-Ni3S2) was in situ grown on Ni foam by a GQDs induced hydrothermal method and directly used both as a HER and OER electrocatalyst. The in situ coupling of GQDs and molybdenum doping Ni3S2 not only allow the modulation of electrochemical behavior, but also enhance electrical conductivity and expose more active sites. Benefiting from the inductive effect of GQDs, the in situ formed G-Mo-Ni3S2 porous structure showed outstanding HER performance with a low overpotential of 68 mV at 10 mA cm−2 and OER property with overpotential of 326 mV at 20 mA cm−2 in 1.0 M KOH, respectively. In addition, a two-electrode cell using G-Mo-Ni3S2 is constructed to deliver low cell voltage of 1.58 V at water-splitting current of 10 mA cm−2 with remarkable stability for more than 50 h. This work serves as a promising strategy for the construction of efficient bifunctional electrocatalyst for overall water splitting.