Antimony (Sb)-doped Bi2S3 nanorod films for photoelectrochemical water splitting

Bi₂S₃ is a promising material for photoelectrochemical (PEC) water splitting due to its favorable optoelectronic properties, abundance of non-toxic elements, and chemical stability. However, pure Bi₂S₃ exhibits low photocurrent efficiency due to charge recombination and slow charge transport. To enhance its performance, we doped antimony (Sb) into the Bi₂S₃ matrix, improving both its physical and PEC characteristics. The Sb doping concentration was varied from 0 to 3.1 at.% in Bi₂S₃ films, which were fabricated through chemical bath deposition followed by annealing. Undoped Bi₂S₃ formed nanorods with a direct bandgap of 1.26 eV and achieved a photocurrent density of 4.5 mA/cm² at 1.0 V vs Ag/AgCl. Sb doping at 0.9 at.% increased both crystallite size and nanorod density, resulting in a bandgap of 1.43 eV and a photocurrent density of 7.0 mA/cm². At higher Sb concentrations (2.2 to 3.1 at.%), the nanorod size further increased, while the bandgap decreased to 1.20 eV, with a corresponding increase in photocurrent density to 8.6 mA/cm². These results demonstrate that Sb doping significantly enhances the nanorod density, photocurrent, and stability of Bi₂S₃ photoelectrodes.