Gas sensing properties of palladium-modified zinc oxide nanofilms: A DFT study

Abstract

The improved gas-detecting ability of ZnO nanostructures has generated considerable attention for further development based on a unique and practical approach. However, reduced gas sensitivity and selectivity, as well as the sophisticated synthesis requiring high-cost technology restricts its efficient use. In this regard, the enhancement of gas sensing properties can be brought about by incorporating the noble metal palladium (Pd) to modify the ZnO surface. This work applied density functional theory (DFT) calculations to study such sensing materials to the target gases (i.e., hydrogen (H2) and ethanol (C2H5OH)), which are extensively applied in energy production, thereby requiring rapid and accurate detection. The modified ZnO thin film-based gas sensor was modeled into Pd-substitutional doped and Pd-decorated ZnO surfaces. The charge transport phenomenon at the atomic scale, binding strength, and other electronic and structural properties were elucidated as the varied number of Pd. Pd-decorated ZnO surfaces enhance the sensitivity of both molecules. The calculation results could provide an atomistic insight and a better understanding of altered electrical and sensing properties of ZnO surface modification by Pd atoms.