Abstract
This review focuses on tungsten oxide (WO(3)) and its nanocomposites as photoactive nanomaterials for photoelectrochemical cell (PEC) applications since it possesses exceptional properties such as photostability, high electron mobility (~12 cm(2) V(-1) s(-1)) and a long hole-diffusion length (~150 nm). Although WO(3) has demonstrated oxygen-evolution capability in PEC, further increase of its PEC efficiency is limited by high recombination rate of photogenerated electron/hole carriers and slow charge transfer at the liquid-solid interface. To further increase the PEC efficiency of the WO(3) photocatalyst, designing WO(3) nanocomposites via surface-interface engineering and doping would be a great strategy to enhance the PEC performance via improving charge separation. This review starts with the basic principle of water-splitting and physical chemistry properties of WO(3), that extends to various strategies to produce binary/ternary nanocomposites for PEC, particulate photocatalysts, Z-schemes and tandem-cell applications. The effect of PEC crystalline structure and nanomorphologies on efficiency are included. For both binary and ternary WO(3) nanocomposite systems, the PEC performance under different conditions-including synthesis approaches, various electrolytes, morphologies and applied bias-are summarized. At the end of the review, a conclusion and outlook section concluded the WO(3) photocatalyst-based system with an overview of WO(3) and their nanocomposites for photocatalytic applications and provided the readers with potential research directions.