Insight into bismuth tungstate (Bi2WO6) and titanium dioxide (TiO2) doping strategies for enhanced photocatalytic performance: a comprehensive review

Abstract

Titanium dioxide (TiO₂) and bismuth tungstate (Bi₂WO₆) are prominent photocatalysts hampered by rapid charge carrier recombination. While various enhancement strategies exist, noble metal doping (e.g., Ag, Au, and Pt) introduces unique interfacial phenomena—such as the Schottky barrier and localized surface plasmon resonance (LSPR)—that fundamentally alter their performance. This review provides a critical analysis of noble metal doping strategies for TiO₂ and Bi₂WO₆, highlighting a fundamental distinction: for wide-bandgap TiO₂, doping primarily extends light absorption into the visible spectrum, whereas for visible-light-active Bi₂WO₆, it mainly enhances charge separation. We comprehensively evaluate key synthesis techniques—including impregnation, photodeposition, hydrothermal, and deposition–precipitation—comparing their effectiveness in achieving optimal metal dispersion and photocatalytic efficiency. Furthermore, the influence of critical parameters such as precursor concentration, pH, and irradiation conditions on the doping process is systematically discussed. Finally, this review outlines current challenges and future perspectives, emphasizing the need for cost reduction via bimetallic systems, application against emerging contaminants, and advanced mechanistic studies. By offering a comparative guide to material-specific doping outcomes, this work aims to inform the rational design of high-performance noble-metal-doped photocatalysts for environmental and energy applications.