Insights into the adsorption mechanisms of VOCs molecules on non-oxidized and oxidized SnO2 (110) monolayer: DFT analysis.

CONTEXT: Designing efficient sensitive materials for the detection of volatile organic compounds (VOCs) such as ethanol, acetone, and benzene is stringent owing to the significant environmental and health risks induced by these compounds, in addition to their role as biomarkers for chronic diseases and food quality. This study investigates the adsorption mechanisms of VOC molecules (ethanol, acetone, and benzene) on both non-oxidized and oxidized SnO2 (110) monolayers and identifies the most suitable surface for gas sensing applications. For this, we examined structural properties, adsorption energies, density of states, gas responses, and recovery times. Additionally, we identified the most stable adsorption sites for each gas. Our results indicate that the oxidized SnO2 surface exhibits superior adsorption properties, response sensitivity, and recovery times, making it more effective for detecting VOC molecules, with particularly high sensitivity to ethanol. These findings are consistent with reported experimental results.

METHODS

The calculations were performed using density functional theory (DFT), implemented in the Quantum ESPRESSO code. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional was employed, along with a plane-wave basis set and a cutoff energy of 65 Ry. A comprehensive analysis of various VOC gas interactions with SnO2 surfaces was identified by examining the most stable adsorption sites for each gas.