Surface defects control for ZnO nanorods synthesized by quenching and their anti-recombination in photocatalysis

Abstract

ZnO nanorods with controllable surface defects was synthesized by high-temperature quenching method, and the recombination of photogenerated electron–hole pairs had been drastically suppressed, thus significantly improving the photocatalytic reactivity. The as-prepared samples were characterized for the surface structure, chemical state, phase structure as well as optical absorption using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescent spectrophotometer (PL), diffuse reflectance UV–visible spectroscopy (DRS) and zeta potential. With XPS valence band spectra characterization, its light absorption enhancement in UV–vis range was found due to induced additional electronic states above the valence band edge. Specific types of defects related to the quenching process were further investigated. Moreover, the concentration of surface defects and the recombination of carriers were controllable by quenching temperature, also affected by cooling rates. It provides a time-saving and straightforward method to suppressed recombination of photo-induced carriers and increased UV–vis light absorption for highly efficient ZnO-based photocatalyst applied to environmental remediation.