In-situ construction of Cu3SnS4/α-Fe2O3 S-scheme heterojunction on carbon steel for enhanced photoelectrochemical cathodic protection

A robust all-inorganic S-scheme Cu 3 SnS 4 (CTS4)/ α-Fe 2 O 3 composite nanotube array photoanode, demonstrating superior photoelectrochemical cathodic protection (PECCP) performance, was fabricated by in-situ growing α-Fe 2 O 3 on carbon steel through anodization, followed by anchoring CTS4 nanoparticles onto the vertically aligned nanotubes using a hydrothermal method. The construction of the CTS4/α-Fe 2 O 3 S-scheme heterojunction broaden visible light absorption capability and optimize charge carrier separation simultaneously, enabling significantly enhancing the prevention of Q235 carbon steel corrosion. Under visible light, the optimized composite on Q235 steel coupling led to a 480 mV OCP drop (vs. Ag/AgCl) and a photocurrent density of 32 µA/cm². A synergistic effect between the electron transport channels in nanotube arrays and the charge separation induced by the S-scheme mechanism underpins the substantial performance improvement. This work provides new insights into the design of highly efficient S-scheme photoanodes for stable and sustainable marine corrosion protection.