Enhancing gas sensing properties of novel palladium-decorated zinc oxide surface: a first-principles study

Doping and surface engineering of zinc oxide (ZnO) nanostructures are the practical approach in promoting the gas sensing capabilities. However, the mechanism and the factors that affect such improvement are not well understood. We performed the first-principles based on density functional theory (DFT) calculations to investigate palladium (Pd) decoration on the gas sensing properties of ZnO (0001) surface. Various Pd loading contents on the ZnO surface have been simulated for the resulting sensing capabilities towards a series of gas molecules. The simulations indicate that the modified ZnO surfaces actively interact with the CO and NH3 gas molecules with great adsorption energies ranging from -1.02 eV to -5.56 eV. Moreover, the most stable structure of the decorated ZnO surface by a three-Pd ring cluster has revealed the drastically enhanced selectivity towards NH3 gas. Hence, surface decoration by Pd atoms could be an effective approach in promoting gas selectivity and sensitivity.