Enhancing triethylamine sensing of ZIF-derived ZnO microspheres arising from cobalt doping and defect engineering

Reasonable doping is beneficial to the generation of defects, which is a feasibility strategy to improve the ZnO sensing performance. Herein, we presented an in situ self-sacrificing template strategy for fabricating Co doped h-ZnO core-shell structures (h-ZnO/ZnCox) with different defect contents, pyrolyzing hierarchical porous ZnO (h-ZnO) sub-microspheres coated by zeolite imidazolate frameworks (h-ZnO/ZIF-ZnCox). The investigations of X-ray photoelectron (XPS), photoluminescence (PL) and Raman spectra indicate that donor defects include zinc interstitial (Zni) and oxygen vacancy (VO) in h-ZnO/ZnCox can be tuned by Co dopant (x = 0-30%). Resultantly, the h-ZnO/ZnCox exhibits a significantly enhanced response and selectivity towards triethylamine (TEA), beyond the undoped h-ZnO, and 15% Co-doped h-ZnO (h-ZnO/ZnCo15%) conducts the maximum responses of 1020 to 50 ppm TEA at 573 K, in the top set for the similar type of sensors. Further, the sensing mechanism of h-ZnO/ZnCox is elaborated, possibly resulting from abundant active oxygen species conversed from more oxygen adsorbed which corresponds to cobalt doping generating rich donor-related defects and additional electrons in h-ZnO/ZnCo15%.