Photoelectrochemical performance with nanostructured WO3 films prepared by hot wire chemical vapor deposition

Hot wire chemical vapor deposition (HWCVD) is a technique for synthesizing metal oxides through reactions between evaporated wires and reactive gases. WO 3 films of different thicknesses were successfully obtained by varying the input power while maintaining a consistent morphology. In addition, nanostructured WO 3 films with granular, cauliflower-like, and filamentous morphologies were generated by adjusting the oxygen pressure. This study is the first to explore the potential of WO 3 films only synthesized by HWCVD as photoanodes for photoelectrochemical (PEC) water splitting. Tungsten trioxide films of appropriate thickness exhibited high photocurrent density, and the onset potential varied significantly depending on the film morphology. The HWCVD method can easily achieve adjustable PEC performance of WO 3 films in a controlled manner. • Hot wire chemical vapor deposition (HWCVD) was used to prepare nanostructured WO 3 films. • Film morphology and thickness were controlled by adjusting oxygen pressure and input power. • First demonstration of HWCVD WO 3 films as photoanodes for PEC water splitting. • Cathodic shift of 0.41 V in onset potential achieved via oxygen vacancy engineering. • Provides a simple, scalable, and low-cost method for fabricating efficient WO 3 photoanode.