Surface-active site engineering: Synergy of photo- and supermolecular catalysis in hydrogen transfer enables biomass upgrading and H2 evolution

The appropriate regulation of photocatalyst band structure by simultaneous introduction of active sites is an effective strategy in constructing efficient photocatalytic systems for biomass valorization. Herein, a renewed host-guest photocatalyst (Ov-WO3@CB[5]) prepared by anchoring cucurbit[5]uril on oxygen vacancy-rich WO3 was efficient for reductive upgrading of biomass derivatives using NH3-BH3, such as cascade photocatalytic hydrogenation-cyclization of ethyl levulinate to gamma-valerolactone (up to 99 % yield) at 25 degrees C in 1 h, and quan-titative production of primary/secondary bio-alcohols or arylamines from various aldehydes/ketones or nitro-arenes, respectively. Also, the rate of H2 production by direct photocatalytic hydrolysis of NH3-BH3 could reach 5.75 mL h-1 g-1. The inclusion of cucurbit[5]uril effectively adjusted the semiconductor band structure and enhanced migration efficiency of photo-generated carriers, and the hydrophobic cavity of cucurbit[5]uril favored the entrance of NH3-BH3, as elaborated by theoretical calculations. Properly engineering supramolecular surface-active sites based on interface host-guest chemistry opens new avenues for reductive upgrading of biomass and hydrogen evolution.

Automated summary

The appropriate regulation of photocatalyst band structure by introducing active sites is an effective strategy for constructing efficient photocatalytic systems for biomass valorization. In this study, a renewed host-guest photocatalyst (Ov-WO3@CB[5]) was prepared by anchoring cucurbit[5]uril on oxygen vacancy-rich WO3. It demonstrated efficient reductive upgrading of biomass derivatives and quantitative production of bio-alcohols or arylamines. The inclusion of cucurbit[5]uril adjusted the semiconductor band structure, enhanced carrier migration efficiency, and facilitated the entrance of NH3-BH3, as supported by theoretical calculations.