Photocathodic protection: Fundamental mechanisms and advanced photoanode design strategies

Photocathodic protection (PCP) has emerged as a sustainable and solar-driven alternative or complement to conventional cathodic protection systems, enabling corrosion prevention by harvesting abundant solar energy. This review provides a comprehensive and integrative summary of recent progress in PCP, with a particular focus on evaluation methods, fundamental working mechanisms, and multi-dimensional optimization strategies of photoanodes. Distinct from previous reviews, we systematically classify and compare modification strategies—such as morphology engineering, heterojunction design, cocatalyst loading, and coupling with pseudocapacitors—not only from a material design perspective but also in terms of their practical applications. Moreover, this review provides often overlooks but crucial aspects such as long-term continuous PCP systems, more durable photoanodes, enhanced PCP performance in marine environments, and environmental concerns, all of which are crucial for advancing real-world applications. By bridging fundamental insights and practical implementation challenges, this work aims to offer a forward-looking roadmap for developing efficient, durable, and ecologically responsible PCP systems in real-world applications.