Rapid and Controllable Flame Reduction of TiO2 Nanowires for Enhanced Solar Water-Splitting

Abstract

We report a new flame reduction method to generate controllable amount of oxygen vacancies in TiO₂ nanowires that leads to nearly three times improvement in the photoelectrochemical (PEC) water-splitting performance. The flame reduction method has unique advantages of a high temperature (>1000 °C), ultrafast heating rate, tunable reduction environment, and open-atmosphere operation, so it enables rapid formation of oxygen vacancies (less than one minute) without damaging the nanowire morphology and crystallinity and is even applicable to various metal oxides. Significantly, we show that flame reduction greatly improves the saturation photocurrent densities of TiO₂ nanowires (2.7 times higher), α-Fe₂O₃ nanowires (9.4 times higher), ZnO nanowires (2.0 times higher), and BiVO₄ thin film (4.3 times higher) in comparison to untreated control samples for PEC water-splitting applications.