Efficient Z-scheme of 2D ZnIn2S4/3D TiO2 for enhanced photoelectrochemical cathodic protection

Photoelectrochemical cathodic protection (PCP) driven by solar energy represents a promising alternative to conventional corrosion protection methods. However, severe photocarrier recombination within the photoanode remains a major obstacle limiting PCP efficiency. Herein, a Z-scheme heterojunction composed of 3D TiO 2 nanotube arrays (T) and 2D ZnIn 2 S 4 (ZIS) nanoflowers was rationally constructed for the controllable growth and effective application in the PCP of Q235 steel. Benefiting from the Z-scheme charge transfer pathway, intimated interfacial contact, and broad UV–visible light absorption capability, the T/ZIS heterojunction exhibited significantly enhanced charge separation and transport efficiency. In the optimized configuration, the open-circuit potential under illumination (OCP L ) of T/ZIS-5 coupled with Q235 reached −1.07 V vs. SCE, accompanied by a photocurrent density of 240 μA/cm 2 , over 6-fold higher than that of bare T and superior to other reported photoanodes under similar conditions. This work highlights the important role of electrode design and interface engineering in optimizing PCP performance and provides valuable insights for the development of high-performance heterojunction-based photoelectrodes for solar-driven corrosion protection in marine environments.