Depositing reduced graphene oxide onto tungsten disulfide nanosheets via microwave irradiation: confirmation of four-electron transfer-assisted oxygen reduction and methanol oxidation reaction

Abstract

Optimal morphology tailoring and complete utilization of the nanomaterial components are the effective parameters for improving the electrocatalytic activity of nanomaterials in both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). In the present work, a core–shell reduced graphene oxide (rGO) on tungsten sulfide (WS₂), i.e., rGO@WS₂ nanostructure was successfully prepared via microwave irradiation, which was found to catalyze the four-electron ORR in a 0.1 M KOH aqueous solution. The rGO@WS₂ nanostructure showed an onset potential of 0.94 V and a 1.68-fold increase in the kinetic current density (−5.9 mA cm⁻²) for the ORR as, compared to the bare WS₂ nanosheets. The superior performance of the rGO@WS₂ nanostructure posits it as one of the efficient noble-metal-free ORR and MOR electrocatalysts. Predominantly, this work demonstrates the importance of an appropriate core–shell rGO@WS₂ nanostructure in achieving high intrinsic activity for the four-electron ORR and MOR with significantly enhanced efficiency.