TI Theoretical Insights into CO Oxidation over MOF-808-Encapsulated Single-Atom Metal Catalysts EA JUL 2021
AB Metal-organic framework (MOF)-encapsulated single-atom metal catalysts (SACs), as a bridge between homogeneous and heterogeneous catalysts, have received extensive attention from both fundamental and applied perspectives in recent years. Herein, the CO oxidation reaction mechanism and kinetics over a series of MOF-808-encapsulated SACs (MOF-808-M-II, M = Zn, Cu, Fe, Pd, Ni, and Pt) were studied using density functional theory calculations and microkinetic modeling analysis. First, it has been found that the stability of single-atom metal ions at the Zr metal node follows the trend of Pt-II > Ni-II > Pd-II > Fe-II > Cu-II > Zn-II. Four possible reaction routes, that is, Langmuir-Hinshelwood (LH) mechanism, Eley-Rideal mechanism, CO oxidation with the mu(3)-O site, and the hydroxyl group over MOF-808-Pt-II, were systematically investigated. The LH mechanism is the most favorable CO oxidation route, in which the first CO oxidation step is the kinetically relevant step over MOF-808-Pt-II. Using the energetic span model, the relative turnover frequencies of CO oxidation over MOF-808-M-II were calculated, indicating that the MOF-808-Pt-II catalyst is the most active catalyst among six MOF-808-M-II catalysts.
