Thin MoS2 nanosheets grafted MOFs-derived porous Co–N–C flakes grown on electrospun carbon nanofibers as self-supported bifunctional catalysts for overall water splitting

Abstract

Active and stable non-precious metal electrocatalysts are critical for the large-scale production of hydrogen/oxygen. Herein, a facile strategy for the in situ growth of MOFs combined with carbonization and subsequent solvothermal treatment for the rational design of thin MoS₂ nanosheets grafted Co–N–C flakes (CoNC@MoS₂) and grown on electrospun carbon nanofibers (CNFs) as bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER/OER) is reported. Binder-free CoNC@MoS₂/CNF films exhibited unique hierarchical architectures with interconnected vine-like CNFs, which imparted favorable flexibility and satisfactory electrical conductivity to the self-supported electrocatalysts for electrochemical reactions. Due to the synergistic effect of the CoNC@MoS₂ hybrid nanostructures and fast mass-transport properties of porous carbons, the resultant CoNC@MoS₂/CNFs exhibited high catalytic activities and favorable stabilities for the HER and OER in a basic medium. When acting as electrocatalytic electrodes for overall water splitting, CoNC@MoS₂/CNF films displayed a low overpotential of 1.62 V to generate a current density of 10 mA cm⁻² with remarkable stability at different voltages for 200 000 s, and even outperformed Pt/C–RuO₂ electrode in high current density water electrolysis. This study highlights the rational design of hybrid nanostructures based on MOFs and CNFs as efficient self-supported electrocatalysts, opening new possibilities for the fabrication of functional free-standing materials in energy chemistry.