Band gap modulation of nanostructured WO₃ nanoplate film by Ti doping for enhanced photoelectrochemical performance

Abstract

Despite being a promising photoanode material for water splitting, WO₃ has low conductivity, high onset potential, and sluggish water oxidation kinetics. In this study, we designed Ti-doped WO₃ nanoplate arrays on fluoride-doped tin oxide by a seed-free hydrothermal method, and the effects of doping on the photoelectrochemical performance were investigated. The optimal Ti-doped WO₃ electrode achieved a photocurrent density of 0.53 mA/cm² at 0.6 V (vs Ag/AgCl), 110% higher than that of pure WO₃ nanoplate arrays. Moreover, a significant cathodic shift in the onset potential was observed after doping. X-ray photoelectron spectroscopy valence band and ultraviolet — visible spectra revealed that the band positions of Ti-doped WO₃ photoanodes moved upward, yielding a lower onset potential. Furthermore, electrochemical impedance spectroscopy measurements revealed that the conductivities of the WO₃ photoanodes improved after doping, because of the rapid separation of photo-generated charge carriers. Thus, we report a new design route toward efficient and low-cost photoanodes for photoelectrochemical applications.

Keywords

WO₃ / Ti doping / photoanode / band structure engineering / surface charge separation

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