Ni-CoS₂ nanoparticles loaded on 3D RGO for efficient electrochemical hydrogen and oxygen evolution reaction

The development of efficient non-precious metal electrocatalysts for electrochemical water splitting is still a huge challenge. In this study, we designed and synthesized an efficient electrocatalyst for Ni-doped cobalt sulfide supported on 3D RGO (Ni-CoS₂/3D RGO) using a simple one-step solvent-thermal method. Ni doping adjusted the charge distribution on the surface of the material, significantly improved the catalytic activity, and then accelerated the reaction kinetics. The high specific surface area and high stability of 3D RGO greatly improved the intrinsic activity of the material, making Ni-CoS₂/3D RGO exhibit superior catalytic activity in both electrochemical hydrogen evolution and oxygen evolution. We evaluated the morphology and properties of the catalysts through a series of characterization methods and electrochemical performance tests. When the current density is 10 mA cm⁻², the HER overpotential of Ni-CoS₂/3D RGO under acidic condition reaches 138 mV, and the Tafel slope is 61 mV dec⁻¹. Under alkaline conditions, the OER overpotential reaches 286 mV, and the Tafel slope is only 48 mV dec⁻¹. And the OWS overpotential of the catalyst is 1.41 V and 1.82 V under acidic and alkaline conditions, respectively, indicating that the catalyst has ideal water splitting performance. This work provides a new idea for the application of 3D reduced graphene oxide in electrochemical direction, and also provides a new strategy for the design and preparation of non-precious metal catalysts for the efficient electrochemical water splitting.