In (Sb2Se3-Control) to 17.1 mA cm -2 (Sb2Se3-Sn (0.5)) at 0 VRHE, with FF rising from 21.5% to 28.7%. These findings underscore the potential of our approach to enhance Sb2Se3 photocathode performance in PEC applications. Future efforts should focus on optimizing film thickness and orientation, aiming for improved light absorption and enhanced charge separation efficiency, thus further enhancing PEC performance.