Oxygen vacancies dominated CuO@ZnFe2O4 yolk-shell microspheres for robust and selective detection of xylene

Abstract

Abstract Hierarchical ZnFe2O4 yolk-shell microspheres (ZFO YSMSs) with the large specific surface area are synthesized using a facile self-template strategy followed by a thermal treatment method. Subsequently, different amounts of CuO are decorated on ZnFe2O4 YSMSs (CZFO YSMSs) via a simple solvothermal method. Various techniques are employed to study the microstructure, morphology, chemical composition, oxidation states and surface area of ZFO and CZFO YSMSs, including XRD, SEM, TEM, XPS and BET analysis. The crystallite sizes, pore diameters and grain diameters of the ZFO and CZFO3 YSMSs are calculated statistically, and their sensing performances are investigated systematically, including optimum operating temperature, selectivity, response/recovery time, detection limit and long-term stability. The experimental results indicate the CZFO YSMSs-based sensor shows remarkable selectivity (e.g., Sxylene/Stoluene\u2009=\u20093.21) as well as good sensitivity to xylene. The improved sensing properties could be ascribed to the catalytic action of CuO for the oxidation of xylene and the increase of absorbed oxygen species caused by oxygen vacancies (Ov).