Selective and tunable H2 adsorption/sensing performance of W-doped graphene under external electric fields: A DFT study

Abstract

W-doped graphene and its selective gas adsorption/sensing performance are studied through first-principles density functional theory (DFT) calculations. A single W atom is stably anchored into the graphene plane with a high binding energy of −9.325 eV. The W-doped graphene interacts more strongly with H2 compared to NH3, CH4, CO, SO2 or H2S. The H2 adsorption system also has a higher adsorption energy of −1.035 eV. Furthermore, the W-doped graphene exhibits the highest sensor response to H2 with the largest number of transferred charges and the biggest change in the band gap. A negative electric field improves the interaction between the H2 and the W-doped graphene by increasing the adsorption energy and promoting charge transfer. However, the adsorption of the H2 is significantly weakened upon the application of a positive electric field; the adsorbed H2 is easily desorbed from the W-doped graphene with a modulated recovery time as short as ∼4.099 s at room temperature (300 K) upon a +0.4 V Å−1 increase in the electric field. These results reveal that the W-doped graphene has promising selective and tunable H2 adsorption/sensing performance upon the application of external electric fields.