Effect of oxygen deficiency on vis-light photocatalytic activity in AZO

Abstract

Aluminium (Al)-doped zinc oxide (ZnO) photocatalyst with surface oxygen vacancies was synthesised by one-step hydrothermal method. The oxygen vacancies drawn into ZnO surface by Al doping can effectively enhance visible (vis)-light photocatalytic activity. The crystal structure, chemical composition and morphology of Al-doped ZnO (AZO) photocatalysts were characterised by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy (TEM). The optical property was characterised by ultraviolet–vis diffuse reflectance spectra. High-resolution TEM and electron paramagnetic resonance spectra mainly confirm the existence of oxygen vacancies on the ZnO surface. Oxygen vacancies result in a narrowing of the bandgap (Eg = 2.92 eV) and an increase in the vis-light absorption of the sample. AZO sample exhibits good cycling stability, and no obvious decrease in the photocatalytic activity was observed even after four cycles.