Three-dimensional P-doped Co8FeS8-Co2P-Fe2P heterogenous nanocatalyst for high-efficiency alkaline hydrogen evolution reaction

Abstract

The development of durable and highly active electrocatalysts free of precious metals remains a significant challenge in achieving sustainable hydrogen (H₂) production via water splitting. In this study, we present an innovative three-dimensional (3D) heterogeneous phosphorus-doped bimetallic phosphide electrocatalyst. This catalyst, comprising Co₈FeS₈, Co₂P, and Fe₂P, is synthesized in situ on a nickel foam (NF) substrate. By constructing a unique 3D composite structure, introducing phosphorus atom doping, and achieving strong interfacial coupling effects between Co₈FeS₈, Co₂P, and Fe₂P, the charge distribution of the catalyst was optimized while exposing abundant active sites. Additionally, the elevated conductivity and massive surface area of the NF substrate contributed to superior electrocatalytic performance and accelerated hydrogen evolution reaction kinetics. The NF/Co₈FeS₈-Co₂P-Fe₂P electrode achieved a low overpotential of 61.8 mV at a current density of 10 mA·cm⁻² in a 1.0 M KOH solution. Density functional theory (DFT) calculations further revealed that phosphorus-doped Fe₂P electrode exhibits an optimal ΔG_H*, facilitating reaction kinetics. The synergistic catalysis of Co₈FeS₈, Co₂P, and Fe₂P materials significantly enhances the hydrogen generation activity of the Co₈FeS₈-Co₂P-Fe₂P electrode. This work provides valuable insights into designing and fabricating reliable and effective three-dimensional hybrid electrode materials for advanced electrochemical applications.