Adsorption of gas molecules on Co-doped SnO2 (110): First-principles investigation

First-principles calculations based on density functional theory were employed to study the adsorption of gas molecules (CH4, CO, H2O) on various SnO2 (110) surfaces. We found that CO and CH4 molecules are weakly adsorbed on intrinsic SnO2 (110) surfaces, and intrinsic SnO2 is sensitive only to the H2O molecule. Compared with the gas molecules adsorbed on the intrinsic SnO2 surfaces, the significantly increased adsorption energy indicates that there is an improvement in the gas sensitivity properties of Co-doped SnO2 (Co/SnO2) and oxygen vacancy modified Co-doped SnO2 (Co/V-O/SnO2) to CO, CH4, and H2O gas. The CO adsorbed on the Co/V-O/SnO2 surface has the strongest adsorption energy (-1.402 eV). We also studied the optical properties of the Co/SnO2 and Co/V-O/SnO2 surfaces influenced by the three gas molecules. We found that the three gas molecules cause an enhancement of the adsorption peaks of Co/SnO2 configuration in the visible light range. Our study benefits research on the potential application of SnO2 sensor materials.