Review of TiO2-Based Heterojunction Coatings in Photocathodic Protection

Photocathodic protection coating is an emerging anticorrosion technology that combines the protective characteristics of coating and cathodic protection. TiO2 is stable and easy to prepare; however, it suffers from a low sunlight utilization rate and low photoelectric conversion efficiency. The construction of TiO2-based heterojunction coatings provides an effective solution to these challenges. This work summarizes the synthesis methods of TiO2-based heterojunction coatings, explores the charge-transfer mechanisms associated with various types of heterojunction coatings (e.g., type II heterojunction, p–n junction, Schottky junction, and Z-scheme heterojunction), and reviews the characterization methods used for heterojunction analysis. Finally, the application prospects and future research directions of TiO2-based heterojunction coatings are proposed. This study will help researchers understand the fabrication process and application of TiO2-based heterojunction coatings in photocathodic protection.