Adsorption and sensing properties of greenhouse gases (CO2, CH4, N2O and SF6) on pristine and Cr modified WSe2 monolayer based on density functional theory

Abstract

With the increasing global warming, monitoring and reducing the content of greenhouse gases in the atmosphere has become a top priority. In this study, we investigated the adsorption and sensing performances of pristine and two Cr-modified WSe2 (Cr-doped and Cr-substituted) monolayers on four greenhouse gases (CO2, CH4, N2O, and SF6) based on DFT, and explored their application prospects as a greenhouse gas sensor. The mechanism of gas sensing was analyzed from the aspects of adsorption energy, charge transfer, density of states (DOS), band structure, sensitivity, desorption time, etc. The experimental results show that both Cr modification methods could significantly improve the adsorption capacity of the intrinsic WSe2 monolayer. The two Cr-WSe2 monolayers possess strong chemisorption on all four gases according to high adsorption energy and charge transfer, so they can be used to purify CO2, CH4, N2O, and SF6 in the atmosphere. In addition, Cr-WSe2 monolayers have good desorption behavior to CO2 and CH4 at high temperatures, which makes them possible to be used as gas-sensing material for recycling under certain conditions. Our research has some theoretical implications for exploring potential sensing materials for the recovery of greenhouse gases.