New aspects of improving the performance of WO3 thin films for photoelectrochemical water splitting by tuning the ultrathin depletion regionElectronic supplementary information (ESI) available. See DOI: 10.1039/c8ra08875f

• Main Authors: Cen, Jiajie, Wu, Qiyuan, Yan, Danhua, Zhang, Wenrui, Zhao, Yue, Tong, Xiao, Liu, Mingzhao, Orlov, Alexander
• Format: Journal Article
• Published: 08.01.2019
• ISSN: 2046-2069
• DOI: 10.1039/c8ra08875f

In this work, we explored a facile, scalable and effective method for substantially enhancing photocurrent and incident-photon-to-current efficiency of WO 3 thin-film photoanodes by a mild reduction treatment under low oxygen pressure. Experimental data from photoelectrochemical and electrochemical impedance spectroscopies have shown that such treatment can increase the charge carrier density on WO 3 photoanode surfaces resulting in improvements in hole collection efficiency and reduction in charge recombination. Despite a much thinner layer of WO 3 (about 500 nm) compared to those in other published studies, the electrodes exhibited an ultra-high photocurrent density of 1.81 mA cm −2 at 1.23 V vs. RHE. This current density is one of the highest ones among WO 3 -based photoanodes described in literature. The proposed surface modulation approach offers an effective and scalable method to prepare high-performance thin film photoanodes for photoelectrochemical water splitting. Surface modulation approach offers an effective and scalable method for high-performance WO 3 photoanodes.