One-step construction of Bi2S3/C-TiO2 heterojunction from NH2-MIL-125(Ti) for enhanced photocathodic protection

Owing to its environmental compatibility and energy conservation properties, photocathodic protection (PCP) has emerged as a promising approach for metal corrosion protection. The key to efficient PCP lies in developing semiconductor composite materials that combine excellent photoelectrochemical performance with a simple preparation process. Herein, a carbon-doped TiO 2 /Bi 2 S 3 composite (Bi 2 S 3 /C-TiO 2 ) was fabricated via a single-step, low-temperature hydrolysis strategy using NH 2 -MIL-125(Ti) as the precursor, concurrently achieving carbon doping and incorporating a narrow-bandgap semiconductor. Characterization by UV-Vis diffuse reflectance spectroscopy and photoelectrochemical testing under illumination revealed that the composite exhibits significantly enhanced visible-light absorption while effectively suppressing photogenerated charge carrier recombination. Under optimized conditions, the Bi 2 S 3 /C-TiO 2 photoanode shifted the potential of coupled 304 stainless steel (304SS) to −464 mV (vs. Ag/AgCl) under visible-light irradiation—substantially below its corrosion potential—demonstrating effective photogenerated cathodic protection for 304SS.