Adsorption/desorption kinetics of nitric oxide on zinc oxide nano film sensor enhanced by light irradiation and gold-nanoparticles decoration

•Gas sensing response/recovery kinetics of NO sensing by ZnO with light irradiation and Au catalytic effect at room temperature.•Molecular dynamics consideration for adsorption and desorption to explain the detection of ppm level gas concentrations.•The nano-effect in varying thicknesses of ZnO. ZnO thin-films with precisely controlled thicknesses were fabricated by the atomic layer deposition and their NO gas sensing properties were investigated at different temperatures, and in particular, under light irradiation of various energy and intensity at room temperature with and without Au catalyst. The molecular dynamics of NO and O2 during the response and recovery cycles in relation with the NO sensing performance in air environment was elaborated using the energy diagram modelled for adsorption and desorption kinetics of the gas molecules. The blue light irradiation combined with Au catalytic effect greatly enhanced the NO response rate, but delayed the recovery rate in the air environment via molecular dynamic interference from the environmental oxygen. The optimum condition for NO sensing was obtained for the film thickness, light energy and intensity. Critical issues for the stable sensor operation such as concentration dependence, gas selectivity, and humidity effect were also reported.