La-Co-Mn perovskite (LCMO) for NO and Hg0 oxidation: Experimental and DFT investigations of adsorption processes

To achieve superior catalytic performance, the development of plausible regulation of pure perovskite structure is necessary, which has become a hot research topic. In this study, manganese (Mn) ions were employed to dope cobalt (Co) ions at the B-site of LaCoO3, yielding a series of LaCo1-xMnxO3 (x = 0.1–0.5) perovskite (LCMO). The oxidation activity of NO and Hg0 was conducted, evaluating the effect of Mn-doping. The results indicated a minor change in NO oxidation activity and a significant enhancement in Hg0 oxidation, reaching above 92% at 100°C–300°C for LCMO. Structural characterization revealed a gradual transition in the phase structure of LCMO from the R-3C diamond phase to the Pm-3m cubic phase with increasing Mn doping. Furthermore, electronegativity properties of LCMO evolved with Co ions at the B-site exhibiting a preference for generating Co2+ over the more active Co3+. Finally, DFT calculations were conducted to analyze the adsorption energies of NO and Hg0 at different active sites on the surfaces of LaCoO3 (110) and Mn-LaCoO3 (110). The results indicated that Mn doping increased the active site amounts and strengthened the adsorption energy of Hg0 on the Mn-LaCoO3 (110) surface. However, the adsorption energy of NO remained largely unchanged, validating the oxidation results. This study offered insights for selecting B-site ions to adjust the perovskite structure of excellent performance, facilitating its industrial application.