Abstract
The construction of heterostructures has been recognized as an effective strategy for enhancing material activity and stability. Herein, a ternary heterojunction FeSe(2)-BiSe(2)-CoSe(2) was synthesized via a hydrothermal selenidation reaction. The significant electronegativity difference between Bi and Fe/Co triggers charge transfer within the FeSe(2)-BiSe(2)-CoSe(2) lattice. Furthermore, the abundant pore structure of FeSe(2)-BiSe(2)-CoSe(2) provides efficient pathways for electron diffusion, significantly enhancing the HER catalytic kinetics. Results demonstrate that FeSe(2)-BiSe(2)-CoSe(2) exhibits outstanding HER activity in both acidic and alkaline media. In 0.5 M H(2)SO(4), it exhibits an overpotential of only 44 mV with a Tafel slope of 108 mV dec(-1). In 1 M KOH, the corresponding overpotential is 188 mV, with a Tafel slope of 45 mV dec(-1) at 10 mA cm(-2). This study constructs electron-rich active sites through electronic structure regulation, providing valuable insights for designing low-cost, high-performance transition metal selenide HER catalysts.