Identifying active sites of Co3O4 catalysts for C2H2 oxidation using combined computational and experimental methods†
Abstract
Combined computational and experimental studies are carried out to unravel the role of active centers on C2H2 oxidation over Co3O4 catalysts. Density functional theory (DFT) studies indicate that Co2+ ions on Co3O4 (110)-A exhibit stronger reducibility than Co3+ and oxygen species activated by Co2+ have better catalytic performance. On the Co3O4 (110)-B surface, Co2+ ions represent the presence of oxygen vacancies. O2 can be adsorbed on oxygen vacancies to form active O2− species, which oxidize C2H2 to CO2 and H2O. Co3O4 catalysts with different Co2+ contents are prepared to experimentally verify calculation results. The catalytic activity varies in the order of Co3O4-sheets-reduced > Co3O4-sheets > Co3O4-sticks-reduced > Co3O4-sticks, in accordance with the trend of Co2+ contents. Furthermore, microkinetic studies prove that the key factor of C2H2 oxidation is C–C dissociation. Decreasing the C–C cleavage barrier significantly enhances the overall reaction rates. Both computational and experimental results show that the presence of Co2+ on the surface of the Co3O4 catalyst is the main contributing factor to the activity of C2H2 oxidation. As minimal research has been reported on C2H2 oxidation, this study may provide a guideline for eliminating other volatile organic compounds over Co3O4 catalysts.
- This article is part of the themed collection: Nanomaterials in air