Fabrication and characterization of Co-doped ZnO nanodiscs for selective TEA sensor applications with high response, high selectivity and ppb-level detection limit

Abstract

Pure ZnO and a series of Co-doped ZnO nanostructures with different Co doping amount were successfully synthesized by a simple near room-temperature precipitation method combined with subsequent calcination. The products featured a two dimensional (2D) porous nanodisc-like structure, which were composed of nanoparticles of about 30–100 nm in diameter. A series of structural analysis including XRD, Uv-vis adsorption, XPS and elemental mapping revealed that cobalt entered into the crystal lattice of ZnO uniformly in the form of Co(II) and substituted the Zn sites in tetrahedral coordination. The sensing performance of the products was investigated systematically. The Co-doped ZnO sensors especially CoZnO-3 exhibited a superior performance toward triethylamine (TEA) than the pristine ZnO sensor did, including enhanced response, excellent stability, high selectivity and low detection limit. The mechanism of the products was discussed based on the depletion layer model and the work suggested that the enhancement of gas-sensing performance can be mainly attributed to defects induced by Co-doping, the catalytic effect of Co and the porous structure. Thanks to the facile synthesis strategy and high performance, the Co-doped ZnO nanostructures become one of the promising sensing materials in practical applications.