Enhancing Photoelectrochemical Water Oxidation on WO3 via Electrochromic Modulation: Universal Effects and Mechanistic Insights

Abstract

AbstractAlthough WO3 exhibits both electrochromic and photoelectrochemical (PEC) properties, there is no research conducted to investigate the correlation between them. The study herein reports the electrochromic enhancement of PEC activity on WO3. The electrochromic WO3 (e‐WO3) exhibits a significantly enhanced activity for PEC water oxidation compared to raw WO3 (r‐WO3), with a limiting photocurrent density three times that of r‐WO3. The electrochromic enhancement of PEC activity is universal and independent of the type of cations inserted during electrochromism. Decoloring reduces the PEC activity but a simple re‐coloring restores the activity to its maximum value. Electrochromism induces large amounts of oxygen vacancies and surface states, the former improving the electron density of WO3 and the latter facilitating the hole transfer across e‐WO3/electrolyte interface. It is proved that the electrochromic enhancement effect is due to the significantly improved electron–hole separation efficiency and the charge transfer efficiency across the WO3/electrolyte interface.