Advanced TiO2-Based Photoelectrocatalysis: Material Modifications, Charge Dynamics, and Environmental–Energy Applications

This review presents a comprehensive overview of recent advances in TiO2-based photoelectrocatalysis (PEC), with an emphasis on material design strategies to enhance visible-light responsiveness and charge carrier dynamics. Key approaches—including elemental doping, defect engineering, heterojunction construction, and plasmonic enhancement—are systematically discussed in relation to their roles in modulating energy band structures and promoting charge separation. Beyond fundamental mechanisms, the review highlights the broad environmental and energy-related applications of TiO2-driven PEC systems, encompassing the degradation of persistent organic pollutants, microbial disinfection, heavy metal removal, photoelectrochemical water splitting for hydrogen production, and CO2 reduction. Recent progress in integrating PEC systems with energy harvesting modules to construct self-powered platforms is critically examined. Current limitations and future directions are also outlined to guide the rational development of next-generation TiO2-based photoelectrocatalytic systems for sustainable environmental remediation and solar fuel conversion.