Probing room-temperature reactivity of H<sub>2</sub>S, SO<sub>2</sub>, and NO on the Li<sub>2</sub>MnO<sub>3</sub> crystal surface by experimental and first-principles studies

Abstract

This study delves into the surface reactivity of Li2MnO3 towards H2S, SO2 and NO gases at room temperature, employing both experimental and theoretical calculations. Li2MnO3 was synthesized using a conventional solid-state method. Then, Li2MnO3 was exposed to 100 ppm concentrations of the aforementioned gases, with subsequent spectroscopic and X-ray diffraction analyses, revealing gas-surface interactions within a few atomic layers. X-Ray diffraction demonstrated minimal structural changes post-gas exposure, indicative of surface-level reactions. X-Ray photoelectron spectroscopy and theoretical calculations unveiled the dissociative adsorption of H2S, resulting in various oxidized sulphur species. H2S reactivity was most pronounced at Mn sites, where H2S donated electrons during the process. SO2 adsorption yielded sulphate species, facilitated by electron transfer to Mn-sites. Conversely, NO adsorption identified distinctive Li and Mn sites on the oxide surface. By combining experimental and theoretical insights, it has been confirmed that the chemisorption of these toxic gases over the Li2MnO3 surface is pertinent to their effective removal across temperature ranges. This work advances the utility of Li2MnO3 in diverse gas treatment applications. Chemisorption of H2S, SO2, and NO gas (100 ppm) over Li2MnO3 at room temperature.