Adsorption of carbonyl sulfide on the surface of transition metal-modified Al2O3: A DFT study

This study employs first-principles calculations based on density functional theory (DFT), to systematically investigate the adsorption behavior and underlying mechanism of carbonyl sulfide (COS) on transition metal (Fe, Co, and Cu) modified α -Al 2 O 3 surfaces. Three atomic-scale modification models, such as lattice substitution doping, surface single-atom dispersion, and metal cluster loading, were used to analyze key parameters, including adsorption energy, charge transfer, electronic structure, and C S bonding. The results indicate that metal cluster-loaded systems perform best, with 3Fe ⁎ -Al 2 O 3 exhibiting the strongest COS adsorption. Adsorption energies follow Fe (−3.21 eV) > Co (−2.87 eV) > Cu (−2.45 eV), consistent with the experimental observed catalytic activity trends. Fe’s higher D-band center (0.653 eV) reduces anti-bonding state occupancy, enhancing adsorption. DOS analysis reveals a 1.76 eV rightward shift of the COS molecular orbitals (Fe system) indicating strong chemical adsorption. Differential charge density and Bader analysis confirm Fe clusters donate 0.33 e to COS. LOCPOT electrostatic potential analysis quantifies a rise in the work function of 3Fe*-Al 2 O 3 from 1.12 to 1.24 eV after COS adsorption, evidencing marked electron transfer from Fe clusters to COS and a strong capacity for molecular activation. In 3Fe ⁎ -Al 2 O 3 , the C S bond length elongates by 14.74%, and the ICOHP of −3.597 corresponds to a bond energy reduction of 216.13 kJ/mol, facilitating dissociation. These results clarify the synergistic effects between geometric configuration and electronic properties of metal clusters on COS activation. Combined with the quantitative differences among Fe, Co, and Cu modified systems, this work provides atomic-scale theoretical guidance for the development of high-efficiency desulfurization catalysts for industrial gas purification.