Lewis–Brønsted Dual Acid Sites in WO_3‐<i>_x</i> Catalysts Facilitate Direct Photocatalytic Hydrodeoxygenation of Hydroxy Groups in Alcohols

Efficient hydrodeoxygenation (HDO) of the hydroxy groups (C─OH) in alcohol molecules has attracted substantial attention due to its importance in many research fields such as organic synthesis and biomass conversion. Photocatalytic C─OH direct HDO is a promising but challenging process because of the difficulty in C─O bond activation due to the higher bond energy and strong polarity. A polarity enhancement strategy is proposed and a WO_3- _x catalyst possessing Lewis-Brønsted dual acid sites is developed to realize the direct HDO of alcohols under ambient conditions. The C─O bond is first heterolytic cleaved to produce the carbocation intermediate and then the carbocation will combine with a proton and photogenerated electrons to form a new C─H bond. The synergistic effect of Lewis and Brønsted acid sites plays a key role in promoting the C─O bond cleavage. A series of comparative experiments, spectral characterizations and DFT calculations were used to demonstrate this new photocatalytic HDO pathway. Different alcohols, including polyols, can be directly converted into corresponding alkanes over this system. The present work discloses a direct HDO process for the hydroxy groups in alcohols and provides a new horizon for the design of new photocatalytic systems.