Enhancement effect from ReS₂/Co₉S₈ heterostructure evolution for the highly effective furfural oxidation coupling with hydrogen production

The dynamic evolution of catalyst structures during the electrocatalytic reaction has seriously hindered our comprehensive understanding of catalytic processes and pathways. In this work, we report that the metal-sulfide (ReS₂/Co₉S₈) heterostructure has multiple synergistic effects, enhancing the furfural oxidation reaction (FOR) coupling with hydrogen evolution (HER). Under cathodic reduction conditions, H₂ production can be promoted at specific active sites by the original heterostructure of ReS₂/Co₉S₈. Under anodic oxidation conditions, a new heterointerface of ReS₂/Co₉S₈-Co(OH)₂ is in-situ reconstructed based on the original ReS₂/Co₉S₈ heterostructure. The new ReS₂/Co₉S₈-Co(OH)₂ heterointerface induced by this ReS₂/Co₉S₈ heterostructure significantly enhances FOR performance in an indirect way at 1.33–1.53 V_RHE, resulting in a 86.3 % faradaic efficiency (FE). The optimized composite of ReS₂/Co₉S₈ with different molar ratios in a two-electrode system exhibits superior performance toward HER||FOR, achieving a smaller cell voltage of 1.43 V to reach 10 mA cm⁻² compared to ReS₂||Co₉S₈ (1.69 V). This work verifies the reconstructed heterointerface of ReS₂/Co₉S₈-Co(OH)₂ for FOR and identifies the distinct catalytic mechanisms for FOR and HER.