Adsorption of HF and H₂S on α-Al₂O₃ (0001) Surfaces: A DFT Study

Abstract

Ex-service SF 6 adsorbents in SF 6 gas-insulated electric equipment contain many toxic substances. Inside, HF and H 2 S are two typical toxic gases. Based on the first principle, the interaction process between HF/H 2 S and α-Al 2 O 3 (0001) surfaces was calculated using the density functional theory (DFT). The results showed that the adsorption of HF on α-Al 2 O 3 ( 0001) is stronger than that of H 2 S. Under the five adsorption sites, the adsorption effect of HF−H and HF−F was similar. At O-2 site, the adsorption energy of H 2 S−H adsorption configuration is significantly higher than that of the other four sites. The density of states (DOS) indicated that new peaks appeared after adsorption. The DOS and partial density of states (PDOS) indicated that the adsorption of HF and H 2 S occurs via chemical adsorption. The DOS and PDOS shifted to the right when the S atom was approaching, proving that the system shifts to instability. Compared with the energy gap of α-Al 2 O 3 (0001), HF and H 2 S adsorption systems decreased significantly. The energy gap of the HF adsorption system was 1.173 eV larger than that of the H 2 S system and the geometry was relatively stable, which is consistent with the DOS and PDOS adsorption calculation results. Thus, the adsorption of HF and H 2 S on α-Al 2 O 3 (0001) surfaces was clearly different. The findings of this study may provide theoretical guidance for the adsorption of other gases or developing a new adsorbent.

Surface Structure Analysis and Formaldehyde Removal Mechanism of Lotus Shell Biochar: An Experimental and Theoretical Perspective

“…As a well-established method in quantum chemistry, density functional theory (DFT) has been used to obtain insights into the microscopic mechanisms of pollutant–material interfaces. − HCHO-molecularly imprinted polymers have been designed and synthesized for HCHO removal with the assistance of DFT calculations . Both experimental studies and DFT calculations have been conducted to identify the adsorption behavior of HCHO on resin-based carbons and amine-modified diatomite. , The integration of experimental and DFT methods has emerged as a crucial strategy to identify the fundamental mechanisms involved.…”