Phosphomolybdic acid supported single-metal-atom catalysis in CO oxidation: first-principles calculations

CO oxidation on phosphomolybdic acid (H3PMo12O40, PMA) supported single-metal atom (M = Pt, Au, Co, Cu, Fe, Ir, Ni, Os, Pd, Ag, Rh, and Ru) (M-PMA) catalysts is studied by density-functional-theory (DFT) calculations. Adsorption of CO and O-2 on M-PMA is investigated. Based on electronic structure analysis, O-2 is activated by the single-metal-atom active center. The Langmuir-Hinshelwood mechanism is systematically explored for CO oxidation on M-PMA, and it is found that M-PMAs have high reactivity toward CO oxidation. The Mars-van Krevelen mechanism is also investigated and it is shown to be less likely to be responsible. Our DFT findings will provide useful insight for designing stable, highly active heteropolyacid-supported single-metal-atom catalysts.