Ethanol sensing characteristics of Au and Cl-comodified ZnO nanoparticles

Abstract

Au and Cl-comodified ZnO nanoparticles were prepared by a citric sol–gel method. XRD and TEM showed that the simultaneous introduction of gold and chlorine resulted in smaller crystallite and particle size than the pristine ZnO. XPS revealed that chlorine existed in the form of chloride, while gold was in the mixed states of Au3+ ions and Au0 atoms. Compared with the pristine ZnO, Au-ZnO and Cl-ZnO, the Au,Cl-ZnO nanoparticles exhibited the best and stable ethanol sensing performance, including higher gas response (19.64–100 ppm), sensitivity and selectivity at comparatively lower prime working temperature of 220 °C. The improved ethanol sensing performance was ascribed to the higher surface coverage of adsorbed oxygen species resulting from the substitution of Au3+ for Zn2+ ions and Cl- for O2– ions in the ZnO lattice which increased the concentration of electrons and number of adsorption sites, as well as from the spillover effect of metallic gold with the highly effective dissociation catalytic ability.