Experimental and Density Functional Theory Simulation Research on PdO-SnO Nanosheet Ethanol Gas Sensors.

Pure SnO and 1 at.% PdO-SnO materials were prepared using a simple hydrothermal method. The micromorphology and element valence state of the material were characterized using XRD, SEM, TEM, and XPS methods. The SEM results showed that the prepared material had a two-dimensional nanosheet morphology, and the formation of PdO and SnO heterostructures was validated through TEM. Due to the influence of the heterojunction, in the XPS test, the energy spectrum peaks of Sn and O in PdO-SnO were shifted by 0.2 eV compared with SnO. The PdO-SnO sensor showed improved ethanol sensing performance compared to the pure SnO sensor, since it benefited from the large specific surface area of the nanosheet structure, the modulation effect of the PdO-SnO heterojunction on resistance, and the catalyst effect of PdO on the adsorption of oxygen. A DFT calculation study of the ethanol adsorption characteristics of the PdO-SnO surface was conducted to provide a detailed explanation of the gas-sensing mechanism. PdO was found to improve the reducibility of ethanol, enhance the adsorption of ethanol's methyl group, and increase the number of adsorption sites. A synergistic effect based on the continuous adsorption sites was also deduced.