Boosting photocatalytic hydrogen production coupled with benzyl alcohol oxidation over CdS/metal–organic framework composites

Photocatalytic H2 production or photocatalytic organic oxidation has been extensively studied. However, due to the limitation of the half-reaction, the overall photocatalytic process is unfavorable. Herein, we have coupled H2 production and selective oxidation of organic substrates benzyl alcohol to realize an overall redox cycle reaction without sacrificial agent, which simultaneously obtain two high value-added products of H2 and benzaldehyde in one reaction. The CdS-decorated MOF composites (namely, CdS/MIL-53(Fe)) have been synthesized, and exhibited high photocatalytic activity of H2 (2334 μmol g-1h−1) and benzaldehyde yield (2825 μmol g-1h−1), far exceeding the single component of CdS and MOF, under irradiation of visible light. Photoluminescence (PL), photocurrent, electrochemical impedance spectroscopy (EIS), and Mott-Schottky measurements indicate that the Z-scheme photocatalyst of CdS/MOF composites has faster charge transfer and inhibit the recombination of photo-generated charges, ultimately improve photocatalytic activity. This work provides an overall reaction strategy to obtain two meaningful products at the same time, and also provides ideas for the preparation and mechanism research of advanced Z-scheme photocatalysts for semiconductor/MOF composites.