Unlocking the Electrocatalytic Potential of Sb₂Se₃ for HER via Cu Doping-Induced Phase Conversionand rGO Integration

In this study, we explore the electrocatalytic hydrogen evolution reaction (HER) performance of Cu-doped Sb₂Se₃ anchored to reduced graphene oxide (rGO). Although pristine Sb₂Se₃ is typically inactive for HER, its activity is significantly enhanced through Cu doping and integration with rGO, achieved via a one-step hydrothermal process. The resulting CuSbSe₂-rGO catalyst benefits from the synergistic interaction between rGO and Cu, exhibiting superior HER activity compared with control samples: Sb₂Se₃, Sb₂Se₃-rGO, and CuSbSe₂. The electrochemical characterization demonstrates that rGO incorporation enhances stability, conductivity, and surface area. The optimized CuSbSe₂-rGO catalyst shows enhanced HER performance, with an onset potential of 293 mV, an overpotential of 386 mV at a current density of 10 mA cm^–2, and a Tafel slope of 158 mV dec^–1. The catalyst’s superhydrophilic surface (contact angle <5°) promotes efficient wetting and ion diffusion, further improving HER efficiency. Density functional theory calculations indicate that Cu doping reduces the band gap of Sb₂Se₃ from 1.31 to 1.16 eV due to the distribution of Cu states near the Fermi level, a modification that likely contributes to the observed reduction in the overpotential requirements. These findings highlight the potential of CuSbSe₂-rGO for the advancement of water electrolysis technologies.