A DFT study on the Ag-decorated ZnO graphene-like nanosheet as a chemical sensor for ethanol: Explaining the experimental observations

Abstract

Following an experimental work, density functionals B3LYP, TPSS, PBE, M06-2X, and ωB97X-D were exploited to examine the impact of decorating an Ag atom on a ZnO nanosheet sensitivity to the ethanol gas. The interaction of the pristine ZnO sheet with the ethanol was found to be weak, and the sensing response is 6.2 at 300 K based on the B3LYP results, in agreement with experiment. Decorating an Ag atom on the ZnO sheet increases the adsorption energy of ethanol from −6.1 to −20.0 kcal/mol. Energy decomposing analysis indicates that the interaction converts from noncovalent to covalent by the Ag decoration. Also, the sensing response significantly rises to 72 (experimental value ~55). We showed that the Ag decorated ZnO sheet can selectively detect ethanol gas in the presence of benzene, formaldehyde, toluene, and acetone. A short recovery time of 35 s is found, being comparable with experimental value of 25 s. We introduced a theoretical methodology which can reproduce the experimental results. Both theory and experiment suggest that Ag-decorated ZnO nanosheet may be highly sensitive and selective ethanol sensor with a short recovery time.