First-principles study on the adsorption of gas molecules on Fe, Ti-Doped silicene

In this study, we employ first-principles calculations to investigate the geometric and electronic properties of intrinsic silicene and silicene doped with metal elements Fe and Ti. We analyze the adsorption performance of five gas molecules (CO, SO2, H2S, CH4 and H2CO) on the surfaces of these two materials. For each gas molecule, we determine the optimal adsorption site and calculate parameters such as adsorption distance, adsorption energy, charge transfer, recovery time, and density of states to understand the adsorption mechanism. Our study reveals that the adsorption affinity of the selected gas molecules on intrinsic silicene is relatively weak. The distance between the gas molecules and the intrinsic silicene surface is relatively large, and no stable chemical bonds are formed between them. In contrast, Fe and Ti-doped silicene exhibit relatively higher stability, with the adsorption energies of the gas molecules on their surfaces increasing obviously. The Titanium doping exerts a considerable influence on increasing the band gap and the adsorption energy of silicene compared with the intrinsic one, thus the whole structure is able to reveal semiconductors' properties. In Ti-doped silicene structures, the band gap opens, exhibiting semiconductor properties, and the adsorption energies increase relative to intrinsic silicene. These results indicate that the doping of Fe and Ti atoms enhances the adsorption performance of silicene materials, providing theoretical reference for the gas sensing performance of Fe and Ti-doped silicene materials and the semiconductor performance of Ti-doped silicene.