Synthesis of Fe3O4@CdS@CQDs ternary core–shell heterostructures as a magnetically recoverable photocatalyst for selective alcohol oxidation coupled with H2O2 production

Photocatalytic aerobic oxidation of aromatic alcohols to corresponding aldehydes coupled with producing hydrogen peroxide (H2O2) represents one of the most efficient strategies for converting solar energy into chemical energy. In this work, a magnetically recoverable photocatalyst of Fe3O4@CdS@CQDs ternary core-shell heterostructures is elaborately fabricated through the hydrothermal growth of CdS on Fe3O4 nanospheres with in-situ incorporation of carbon quantum dots (CQDs) and used for selective alcohol oxidation coupled with H2O2 production. The Fe3O4@CdS@CQDs photocatalyst possess distinct advantages of full solar spectral absorption, efficient charge separation, and high stability. The Fe3O4-nanosphere cores not only endow photocatalyst with the characteristics of magnetic recovery but also form Fe3O4@CdS Z-scheme heterojunction to prevent CdS from photocorrosion. The in-situ modified CQDs act as charge mediators to accelerate the photogenerated electron-hole separation and afford active sites to facilitate H2O2 production. As a result, the Fe3O4@CdS@CQDs photocatalyst exhibits excellent performance in selectively converting benzyl alcohol to benzaldehyde accompanied with H2O2 production. The generation rates of benzaldehyde and H2O2 reach up to 57.22 and 27.06 mmol·gCdS-1·h-1, respectively. This work highlights a rational construction of magnetic heterostructure photocatalyst and its application in the photo-redox coupling reactions.