title: Iron-doping-enhanced photoelectrochemical water splitting performance of nanostructured WO3: a combined experimental and theoretical study.
abstract: In this paper, we have studied Fe-doping of nanostructured tungsten trioxide (WO3) and its pronounced effect in promoting the photoelectrochemical (PEC) water splitting performance. Vertically aligned Fe-doped WO3 nanoflakes on fluorine-doped tin oxide (FTO) were synthesized via the hydrothermal method. An X-ray photoelectron spectroscopy (XPS) analysis confirmed the Fe(3+) substitution at the W(6+) site in the prepared films. Broadened visible light absorption was observed in doped films, likely due to the formation of extra band states through doping. The Fe-doping was shown to greatly improve the PEC water splitting performance of WO3. More specifically, the 2 mol% Fe-doped WO3 achieved a photocurrent density of 0.88 mA cm(-2) at 1.23 V versus RHE, approximately 30% higher than that of the undoped WO3 (0.69 mA cm(-2) at 1.23 V versus RHE). This enhancement was attributed to the reduced band gap and the doping-enhanced charge carrier density as confirmed by the absorption spectra and the Mott-Schottky plots, respectively. Finally, first-principles density functional theory (DFT) calculations confirmed that the formation of oxygen vacancies was favored after Fe-doping, contributing to the increased charge carrier density in slightly doped films.
authors.affiliation: Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. chsyang@ust.hk.
authors.forename: Teng
authors.initials: T
authors.lastname: Zhang
authors.forename: Zonglong
authors.initials: Z
authors.lastname: Zhu
authors.forename: Haining
authors.initials: H
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Bai
authors.forename: Shuang
authors.initials: S
authors.lastname: Xiao
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zheng
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Xue
authors.forename: Shihe
authors.initials: S
authors.lastname: Yang