A DFT study on the possibility of embedding a single Ti atom into the perfect stanene monolayer as a highly efficient gas sensor

In this work, we have surveyed, the interaction of various molecules (CO, NO, CO2, NO2, NH3 and SO2) with the pristine and Ti-embedded stanene monolayers employing the first-principles calculations. Firstly, the electronic properties of the pristine and Ti-embedded stanene were investigated. We found that after the adsorption of transition metal on stanene, the charge densities were remarkably accumulated on the embedded metal site. The most stable adsorption geometry, adsorption energies, charge density differences, charge transfer and electronic properties were thoroughly discussed. The results suggest that the Ti-embedded stanene can react with gas molecules more effectively as compared to the pristine one. All the studied gas molecules were strongly chemisorbed on the Ti-embedded stanene monolayer, whereas, on the pristine monolayer, these gas molecules show a weak physisorption. The considerable overlaps between the PDOS profiles of the Ti atom and different atoms of gas molecules indicate the formation of covalent bond between them. Our adsorption energy calculations indicate that the gas molecule interaction with Ti-embedded system gives rise to the most stable configuration as compared with that on the pristine stanene. Besides, the analysis of the charge difference plots represents the accumulation of charge densities on the adsorbed gas molecules. Our results thus suggest superior electronic properties for Ti-embedded stanene monolayers.