Superior sensing sensitivity of ZnFe2O4 nano-octahedrons and sensing reaction molecule mechanism of polar ZnFe2O4 {111} surfaces

A solvothermal process prepared ZnFe2O4 nano-octahedrons with {111} crystal planes exposed. In the gas sensing performance experiment, the product showed good sensing activity towards ethanol, acetone or triethylamine. The sensitivity of the nano-octahedrons is further enhanced by adding 3-coordinated Zn atoms (Zn-3c) on the exposed (111) crystal plane after the surface chloride ions and hydroxyl groups are removed by hydrogenation. The atomic-scale gas-sensitive mechanism is proposed using Zn-3c atoms as sensitive response active sites. It is believed that the Zn-3c plays three roles: adsorbing the O-2 molecule, generating free electrons, and catalyzing the reaction between O-2 and the gas being measured. The sensing mechanism, in which unsaturated metal atoms are reactive sites, explains the sensor's increased sensitivity, which is the basis for developing a high-performance gas detector. (c) 2022 Elsevier B.V. All rights reserved.