Synergizing Inter and Intraband Transitions in Defective Tungsten Oxide for Efficient Photocatalytic Alcohol Dehydration to Alkenes.

Abstract

Photocatalysis under mild conditions is an intriguing avenue for organic chemical manufacturing to confront the serious fossil energy crisis. Herein, we report a direct light-driven alkene production through alcohol dehydration, using nonstoichiometric tungsten oxide of W18O49 nanowires with abundant lattice defects as a photocatalyst. A representative ethylene (C2H4) production rate of 275.5 mmol gcat–1 h–1 is achieved from ethanol (C2H5OH) dehydration, together with excellent selectivity up to 99.9%. The universality of our approach is further demonstrated with other alcohol dehydration. Combining ultrafast transient absorption spectroscopy with in situ X-ray photoelectron spectroscopy, we underline that the inter- and intraband transitions synergistically contribute to such excellent activity. In particular, the intraband transition excites the electrons in defect bands into an energetically “hot” state, largely alleviating the charge recombination. As a result, the C–OH bond of chemisorbed C2H5OH molecules can be effectively dissociated to furnish the formation of C=C bonds. Our work offers a fresh insight into sustainable alkene production with renewable energy input under mild conditions.