DFT study of Cu-modified and Cu-embedded WSe2 monolayers for cohesive adsorption of NO2, SO2, CO2, and H2S

WSe2 monolayers have the great adsorption ability to some gases, especially for industrial waste gases. Density functional theory (DFT) has been used for detailed study of the high adsorption of NO2, SO2, CO2, and H2S using Cu-doped WSe2 monolayers, including density of states, charge density difference, and adsorption energy of the gas/substrate adsorption system, etc. Cu-doped WSe2 monolayers have shown better adsorption of gas molecules, compared with the pure WSe2 monolayer. And Cu-doped WSe2 has shown the chemical adsorption for SO2 and H2S and physical adsorption for NO2 and CO2. However, Cu-doped WSe2 monolayers have two statuses, as Cu-modified and Cu-embedded WSe2 monolayers. It was found that Cu with modifying effect to WSe2 monolayers played a more significant role for NO2 and SO2 adsorption, meanwhile, Cu with embedding effect to WSe2 monolayers played a more significant role for CO2 and H2S adsorption, based on the calculating of the electron localization function. It was also proved that Cu-doped WSe2 can be used as the industrial waste gas sensors and adsorbents.