Density functional theory analysis of the sensitivity of silicene/graphene heterostructures toward HCN

This study investigated the adsorption behavior of HCN molecules on pristine, vacancy-induced defects, and transition-metal doped silicene/graphene heterostructures based on density functional theory. The HCN mole-cules exhibited physical adsorption on pristine silicene/graphene substrates. Introducing Si vacancies did not enhance the activity of silicene/graphene heterostructures, and the HCN molecules continued exhibiting physical adsorption. By contrast, the presence of dopant atoms (Sc, Ti, V, Cr, Mn, Co) enhanced the adsorption stability of HCN molecules. The adsorption of HCN on Ti-doped silicene/graphene heterostructures was the highest, and the results of the partial density of states indicated obvious hybridization between d orbitals of Ti and the p orbitals of HCN molecule. Sc-doped heterostructures exhibited shortest desorption time, suggesting it was suitable as reused sensors for detecting HCN. The obtained results provide new approach for the development of highly sensitive gas sensors based on heterostructures.