Surface Reconstruction-Induced Photocatalytic Methanol\nReduction Reaction on a Rutile TiO<sub>2</sub>(001) Surface

Photochemistry\nof methanol on TiO<sub>2</sub> surfaces is of great\nimportance both fundamentally and industrially. Methanol was previously\nreported only to occur photogenerated hole-participating oxidation\nreactions on TiO<sub>2</sub> surfaces. Herein, we report that, upon\nUV light illumination, the methoxy species formed by methanol dissociation\nat the 5-fold coordinated Ti<sup>4+</sup> sites (CH<sub>3</sub>O(a)<sub>Ti5c</sub>) of a reconstructed rutile TiO<sub>2</sub>(001)-(1 ×\n1) surface also undergoes the C–O bond cleavage into methyl\nfragments mediated by photogenerated electrons, in addition to the\nwell-established photogenerated hole-participating oxidation reactions.\nUpon subsequent heating, the resulting methyl species undergoes hydrogenation\nand coupling reactions into methane and ethane, respectively. Accompanying\ntheoretical calculations showed that the lowest unoccupied molecular\norbital (LUMO) of CH<sub>3</sub>O(a)<sub>Ti5c</sub> is localized almost\nat the conduction band minimum of the CH<sub>3</sub>O-adsorbed reconstructed\nrutile TiO<sub>2</sub>(001)-(1 × 1) surface, indicating the likely\nTiO<sub>2</sub> → CH<sub>3</sub>O(a)<sub>Ti5c</sub> interfacial\nphotoexcited-electron transfer. These results greatly broaden the\nphotochemistry of methanol on TiO<sub>2</sub> surfaces and demonstrate\na photocatalytic methanol-to-hydrocarbon reaction route.