Detection of Oxygen Vacancies in Oxides by Defect-Dependent Cataluminescence.

Abstract

Oxygen vacancies can control a number of distinct properties of oxides. However, rapid and simple detection of oxygen vacancies is a great challenge owing to their elusive species and highly diluted contents. In this work, we have discovered that cataluminescence (CTL) intensity in diethyl ether oxidation reaction on the surface of TiO2 nanoparticles is proportional to the content of oxygen vacancies. The oxygen vacancy-dependent diethyl ether CTL is attributed to the fact that abundant chemisorbed O2 in oxygen vacancies could facilitate its contact reaction with chemisorbed diethyl ether molecules, resulting in an obvious improvement of CTL intensity. Therefore, diethyl ether CTL can be employed as a simple probe for oxygen vacancies in TiO2 nanoparticles. Its feasibility is validated by detecting the CTL intensity of diethyl ether on the surface of TiO2 with variable oxygen vacancies by metal ion-doped TiO2 nanoparticles (Cu, Fe, Co, and Cr) and hydrogen-treated TiO2 nanoparticles at different temperatures. The content of oxygen vacancies by the present CTL probe is in good agreement with that obtained by conventional X-ray photoelectron spectroscopy (XPS) technique. The superior properties of the developed CTL probe over already-developed methods include fast response, easy operation, low cost, long-term stability, and simple configuration. We believe that the oxygen vacancy-sensitive CTL probe has a great potential in distinguishing oxygen vacancies in oxides.