Abstract
Two-dimensional (2D) materials have received much interest as important candidate in gas-sensing applications because of their high surface sensitivity and tunable electronic properties. Nevertheless, pristine graphene (PG) tends to have low adsorption capacity with harmful gases, which restricts its sensing capabilities. Formation of heterostructures like silicene/graphene (Si/G) is a viable approach to increasing surface reactivity. However, the relative adsorption of bromine (Br2), carbon tetrachloride (CCl4) and carbon disulfide (CS2) on both PG and Si/G is not well examined. The paper seeks to explain the adsorption mechanism and electronic response of Br2, CCl4 and CS2 on the surface of the PG and Si/G utilizing first-principles density functional theory (DFT) calculations with particular reference to the impact of silicene (Si) integration on adsorption strength, charge transfer, and sensing selectivity.To study the role of charge redistribution and band-structure modulation during gas adsorption, adsorption energies (Eₐ), frontier molecular orbitals (FMOs), and density of states (DOS) were studied. Si/G heterostructure displayed significantly greater Eₐ and charge transfer strength of CCl4 and CS2 than those of PG, demonstrating improved reactivity and conductivity. CCl₄ and CS₂ exhibited weak physisorption on both substrates. On the other hand, the interaction of both systems with Br2 was uniquely controlled by a chemisorption process. DOS and FMO studies indicated that the band-gap narrowing and electronic reorganization on Si/G, confirming its higher potential as a selective and efficient sensing material to electron-donating gases.