In Situ Generated Ti3+-Mediated Photocatalytic Methanol Decomposition to Carbon Monoxide and Hydrogen on a Rutile TiO2(100) Surface.

Photocatalysis of methanol on the TiO2 surface is a prototype of photocatalytic reactions. Here, we unveil a synergistic effect of photoexcited electrons and holes on converting methanol to CO and H2 on a rutile TiO2(100) surface. Upon Hg light irradiation, photoexcited holes oxidize methoxy species at the 5-fold coordinated Ti4+ sites sequentially to formaldehyde and formate intermediates, while photoexcited electrons reduce the associated Ti4+ sites to Ti3+ sites. The formate intermediates selectively decompose to CO and H2 mediated by the Ti3+ sites at elevated temperatures. These results greatly enrich methanol photochemistry on the TiO2 surface and point to a surface structure engineering strategy of oxide photocatalysts for photocatalytic direct methanol decomposition to CO and H2.