Theoretical studies of MXene-supported single-atom catalysts: Os1/Ti2CS2 for low-temperature CO oxidation

We report herein a new sulfur-functionalized MXene Ti2C (Ti2CS2)-supported osmium-metal single-atom catalyst (SAC) Os1/Ti2CS2 with high low-temperature catalytic activity for CO oxidation. Using periodic density functional theory calculations, the most stable SAC, Os1/Ti2CS2, has been screened from series of group 8–11 transition metal SACs M1/Ti2CS2 (M = Fe, Co, Ni, Cu; Ru, Rh, Pd, Ag; Os, Ir, Pt, Au). The calculations show that it is favorable O2 and to be coadsorbed on Os1 single atom (SA) adsorption energy first molecule slightly higher than CO. Moreover, termolecular co-adsorption + 2CO SA also possible, which oxidation through novel three-molecule reaction mechanism. Accordingly, four different mechanisms, Langmuir-Hinshelwood (L-H), Eley-Rideal (E-R), Langmuir-Hinshelwood-A (TLH-A) Langmuir-Hinshelwood-B (TLH-B), are systematically studied by Os1/Ti2CS2. theoretical studies indicate TLH-B mechanism feasible barrier only 0.74 eV, far lower L-H, E-R TLH-A energies 1.06, 1.09 1.47 respectively. results provide fundamental understanding surface chemistry designing two-dimensional nanomaterials.