Ni-Co bimetallic sulfides grown on carbon nanofibers as robust self-supporting catalysts for water splitting

The incorporation of heteroatoms into carbon structures has been demonstrated to be an efficient catalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the insufficient preparation complexity and durability fall short of meeting the demands of the future hydrogen economy. Herein, a ZIF-67/PDA/BC precursor was prepared using polydopamine-modified bacterial cellulose (BC) as a template. By adjusting the Ni/Co ion ratios, we synthesized NiCo-MOF/PDA/BC with a consistent ZIF-67/PDA/BC structure, followed by obtaining a bimetallic porous carbon-based NiCo-NSC@CBC composite. The NiCo-NSC@CBC-1:4 sample retains its nanotube morphology and Co₉S₈ active phase while exhibiting synergistic effects from the NiCo bimetallic sulfide heterostructure and self-supporting interface. The NiCo-NSC@CBC-1:4 electrode demonstrates remarkable bi-functional electrocatalytic activity and long-term stability when utilized as a self-supported HER/OER electrode, as evidenced by the hydrogen evolution overpotential of 119 mV and the oxygen evolution overpotential of 370 mV at a current density of 10 mA cm⁻². The exceptional performance of the material is primarily due to the synergistic effect resulting from the heterostructure of NiCo bimetallic sulfide and self-supporting interface, as well as the preservation of nanotube morphology and Co₉S₈ active phase. This study establishes a robust groundwork for investigating the surface structure composition and interface effects of self-supporting materials.