Films of WO3 plate-like arrays with oxygen vacancies proportionally controlled via rapid chemical reduction

Abstract

Oxygen vacancy, as a kind of self-doping strategy, has been considered by numerous researchers. Several papers have been published about introducing oxygen vacancies in the semiconductors, which give a viewpoint that the concentration of oxygen vacancies may influence the performance. But few of them focus on how to control the concentration of oxygen vacancies, and how to achieve the goal without using additional equipment (such as sealed tube furnace) for too long time (20 min–4 h without considering the time for rising temperature and cooling). In this paper, oxygen vacancies were introduced into the WO3 vertically plate-like arrays films in a short time by chemical reduction. TiCl3 solutions with different concentrations were used as the reductant, and the concentration of oxygen vacancies of WO3 was proportional to the concentration of TiCl3. After importing oxygen vacancies, WO3 film photoanode showed enhanced photoelectrochemical performance, and the photocurrent of treated WO3 (0.88 mA/cm2 at 1.2 V vs. Ag/AgCl) was 1.27 times that of pristine WO3 (0.69 mA/cm2). However, the photocurrent decreased when the concentration of TiCl3 was too high. The over importation of oxygen vacancies might result in a thicker disorder layer with surface defects and more recombination centers. In such a situation, there was an unsatisfactory transfer and separation ability of photogenerated charges. This study provides new insight into controlling the concentration of oxygen vacancies via a rapid and easy approach.