First-principles study on adsorption behaviors of fluorine-containing gases on pure, Co- and Pd-doped Ag(111) surfaces

Abstract

Based on density functional theory (DFT), the adsorption processes of fluorine-containing gases (F2, hydrogen fluoride (HF), and SOF2) on pure, Co- and Pd-doped Ag(111) surfaces were investigated by first-principles calculation. It is found that three fluorine-containing gases exhibit different adsorption behaviors on different adsorption surfaces. Co-doped Ag(111) surfaces show both physical adsorption and chemisorption, while Ag(111) surfaces and Pd-doped Ag(111) surfaces show chemisorption. Co doping and Pd doping on the Ag(111) surface greatly improves the adsorption properties of adsorbents for F2 and SOF2 gas molecules. Results of electron orbital and charge density difference analyses show that hybridization occurs between fluorine-containing gas molecules and adsorbents during the adsorption process. It results in new chemical bond formation and eventually leads to different adsorption behaviors. The F2_F–Co site is the optimal adsorption site for the F2 molecule, and its charge transfer amount is the largest as well. Co doping and Pd doping have little effect on the adsorption of HF molecules, and HF molecules tend to be preferentially adsorbed at the HF_H–Ag site. The adsorption behavior of SOF2 molecules on different surfaces is different from that of the above two gas molecules. The SOF2 molecule tends to adsorb around the Pd atom, and the O atom is closer to the adsorbent.