First-principles study of hydrogen sulfide decomposition on Sc-TiCO single-atom catalyst.

Context: Hydrogen sulfide gas poses significant risks to both human health and the environment, with the potential to induce respiratory and neurological effects, and a heightened fatality risk at elevated concentrations. This article investigates the catalytic decomposition of HS on a Sc-TiCO single-atom catalyst(SAC) using the density functional theory-based first-principles calculation approach. Initially, the adsorption behavior of HS on TiCO-MXene was examined, revealing weak physical adsorption between them. Subsequently, the transition metal atom Sc was introduced to the TiCO surface, and its stability was studied, demonstrating high stability. Further exploration of HS adsorption on Sc-TiCO revealed direct dissociation of HS gas molecules into HS* and H*, with HS* binding to Sc and H* binding to O on the TiCO surface, resulting in OH groups. Using the transition state search method, the dissociation of HS molecules on the SAC's surface was investigated, revealing a potential barrier of 2.45 eV for HS* dissociation. This indicates that the HS molecule can be dissociated into H and S with the action of the Sc-TiCO SAC. Moreover, the S atom left on the catalyst surface can aggregate to produce elemental S, desorbing on the catalyst surface, completing the catalytic cycle. Consequently, the Sc-TiCO SAC is poised to be an efficient catalyst for the catalytic decomposition of HS.

Methods: The Dmol module in Materials Studio software based on density functional theory is used in this study. The generalized gradient approximation method GGA-PBE is used for the exchange-correlation function. The complete LST/QST and the NEB methods in the Dmol module were used to study the minimum energy path of the dissociation of hydrogen sulfide molecules on the catalyst surface.