New Paradigm for Gas Sensing by Two-Dimensional Materials

The adsorption behavior and electronic transport properties of CO and NH3 molecules on para-C3Si and meta-C3Si monolayers are studied using first-principles calculations and the non-equilibrium Green’s function method. The adsorption sites are determined along with their adsorption energies. It turns out that CO and NH3 molecules physisorb on both monolayers. The current–voltage characteristics show that the para-C3Si monolayer can be used to sense CO and NH3 gases with high sensitivity. In contrast to other two-dimensional materials, the sensing mechanism is not based on charge transfer but on the presence of Dirac states and their susceptibility to symmetry-breaking structural distortions.