Air-promoted light-driven hydrogen production from bioethanol over core/shell CrOx@GaN nanoarchitecture

Abstract Light-driven hydrogen production from renewable liquid biomass derivatives rather than fossil fuels offers an ideal path towards carbon neutrality. 1–3 It is often however operated under an anaerobic condition with the limitations of sluggish kinetics and severe coking. Herein, a disruptive air-promoted strategy is explored for exceptionally efficient and durable light-driven hydrogen production from bioethanol over a core/shell Cr 2 O 3 @GaN nanowires semiconducting architecture. Owing to the unique catalytic attributes of Cr 2 O 3 @GaN, bioethanol is energetically favorable to be adsorbed on the Cr 2 O 3 @GaN interface, followed by dehydrogenation toward acetaldehyde and protons by photoexcited holes. The released protons are then consumed for H 2 evolution by photogenerated electrons. After that, O 2 can be evolved into active oxygen species and promote the continuous deprotonation and C-C cleavage of the key C 2 intermediate, thus significantly lowering the reaction energy barrier of hydrogen evolution from bioethanol and removing the carbon residual with inhibited bioethanol overoxidation. As a result, hydrogen is produced at a high rate of 76.9 mole H 2 per gram Cr 2 O 3 @GaN per hour by only feeding bioethanol, air, and light. Notably, an unprecedented light-to-hydrogen efficiency of 17.6% is achieved under concentrated light illumination of 7 W∙cm -2 . A distinguished turnover frequency of > 2,314,000 mole H 2 per mole Cr 2 O 3 per hour, in conjunction with a superior stability of 180 hours, leads to the achievement of a record-high turnover number of 266,943,000 mole H 2 per mole Cr 2 O 3 . The simultaneous generation of aldehyde from bioethanol dehydrogenation enables the process more economically promising.