Formation, Location, and Photocatalytic Reactivity of Methoxy Species on Keggin 12-H₃PW₁₂O₄₀: A Joint Solid-State NMR Spectroscopy and DFT Calculation Study

Solid-state NMR experiments and quantum chemical Density Functional Theory (DFT) calculations were employed to investigate the formation, location, and photocatalytic reactivity of methoxy species on anhydrous 12-H 3 PW 12 O 40 . Two different types of methoxy species were identified on the methanol-adsorbed 12-H 3 PW 12 O 40 catalyst. Rotational Echo DOuble Resonance (REDOR) NMR experiments combined with quantum chemical DFT calculations demonstrated that the two corresponding methyl groups reside on the O c and O d atoms of the Keggin anion, forming the surface O c CH 3 and O d CH 3 species. Photocatalytic experiments further indicated that the two methoxy species are both photochemically reactive species with the O d CH 3 species being much more reactive, and the methoxy species are preferentially mineralized to the final product CO 2 directly.