UiO-66-NH₂ Octahedral Nanocrystals Decorated with ZnFe₂O₄ Nanoparticles for Photocatalytic Alcohol Oxidation

Photocatalytic selective oxidation of alcohols to aldehydes under mild conditions (atmospheric pressure and room temperature) remains a huge challenge, especially for nanoscale catalysts without precious metals. Herein, ZnFe2O4/UiO-66-NH2 (ZFO/U6N) composites are fabricated via an electrostatic self-assembly process, which follows the Z-scheme interfacial charge transfer pattern. Ultrasmall ZFO nanoparticles are anchored to the surface of U6N uniformly due to the large potential difference, forming a tight heterogenous interface for efficient charge transfer and separation. The optimized ZFO/U6N composite possesses excellent conversion (68%) and selectivity (99%) for photocatalytic oxidation of benzyl alcohol to benzaldehyde in an air atmosphere with AM 1.5G as a light source at room temperature. The fantabulous photocatalytic activity can be ascribed to the Z-scheme charge transfer stratagem, improving the charge transfer and separation efficiency, which can maintain the oxidizing ability of holes in the highest occupied molecular orbital energy level of U6N and the reducibility of electrons in the conduction band of ZFO nanoparticles. In addition, after five recycles, the photocatalytic performance of ZFO/U6N nearly remains constant, indicating the high stability. This work provides a strategy for the optimizing nanoscale photocatalysts for photocatalytic selective oxidation reactions under mild conditions.