Nickel foam/reduced graphene oxide/CoNi2S4-MoO2 nanosheets with a core–shell structure formed: An efficient electrocatalyst for the hydrogen evolution reaction

Abstract

The performance of single-component hydrogen evolution reaction (HER) electrocatalysts in terms of physicochemical properties and electrocatalytic efficiency has shown limitations for large-scale industrial applications. Consequently, developing new HER electrocatalysts with superior performance and mature technology is crucial for advancing this field. In this study, nickel foam/reduced graphene oxide/CoNi₂S₄-MoO₂ (NF/rGO/CoNi₂S₄-MoO₂) was prepared using a combination of water bath and two-step hydrothermal methods. Reduced graphene oxide (rGO) enhances the catalyst’s conductivity and induces uniform distribution of CoNi₂S₄. The sheet-like CoNi₂S₄ provides numerous active sites for the vertically distributed MoO₂ nanosheets, reducing agglomeration and ensuring even distribution on the surface. The synergistic effect among rGO, CoNi₂S₄, and MoO₂, along with their unique structures, facilitates charge transfer, enhancing the material’s electrochemical hydrogen evolution capabilities even more. The synthesized NF/rGO/CoNi₂S₄-MoO₂ nanosheets exhibited excellent electrocatalytic performance. The overpotential of NF/rGO/CoNi₂S₄-MoO₂ was as low as 65 mV in a 1.0 M KOH solution at a current density of 10 mA·cm⁻², and the Tafel slope was 96.48 mV·dec⁻¹.