Effect of Heat Treatment Temperature on Protective Performance of TiO2 Thin Film Photocathode

Photocathode protection technology has garnered significant attention from researchers due to its environmentally friendly and low-carbon attributes. TiO₂ thin films subjected to various heat treatment temperatures were deposited on FTO glass using ultrasonic spray pyrolysis. The films were characterized using XRD, SEM, UV–Vis, PL, and EIS to evaluate their phase structure, micro-morphology, optical properties, carrier separation efficiency, and electrochemical impedance. The corrosion protection of 304SS was assessed in a simulated seawater environment. The results indicated that tetragonal TiO₂ was successfully synthesized at heat treatment temperatures ranging from 450–550°C. Among these, TiO₂ treated at 500°C exhibited higher carrier separation efficiency, smaller electrochemical impedance, and the highest photocurrent density. In a 3.5 wt % NaCl solution, the TiO₂ film treated at 500°C caused the open circuit potential of 304SS to shift negatively to –335 mV, which is 185 mV lower than the self-corrosion potential of 304SS, demonstrating an excellent photocathode protection effect.