One-Step Hydrothermal Synthesis of Sn-Doped Sb₂Se₃ for Solar Hydrogen Production

Antimony selenide (Sb₂Se₃) has recently been intensively investigated and has achieved significant advancement in photoelectrochemical (PEC) water splitting. In this work, a facile one-step hydrothermal method for the preparation of Sn-doped Sb₂Se₃ photocathodes with improved PEC performance was investigated. We present an in-depth study of the performance enhancement in Sn-doped Sb₂Se₃ photocathodes using capacitance-voltage (CV), drive-level capacitance profiling (DLCP), and electrochemical impedance spectroscopy (EIS) techniques. The incorporation of Sn²⁺ into the Sb₂Se₃ results in increased carrier density, reduced surface defects, and improved charge separation, thereby leading to improved PEC performance. With a thin Sb₂Se₃ absorber layer (270 nm thickness), the Sn-doped Sb₂Se₃ photocathode exhibits an improved photocurrent density of 17.1 mA cm^-2 at 0 V versus RHE (V _RHE) compared to that of the undoped Sb₂Se₃ photocathode (14.4 mA cm^-2). This work not only highlights the positive influence of Sn doping on Sb₂Se₃ photocathodes but also showcases a one-step method to synthesize doped Sb₂Se₃ with improved optoelectronic properties.