Efficient C(sp3)-H bond oxidation on perovskite quantum dots based on Ce-oxygen affinity.

Perovskite quantum dots (QDs) have shown attractive prospects in the field of visible photocatalysis, especially in the synthesis of high value-added chemicals. However, under aerobic conditions, the stable operation of QD catalysts has been limited by the reactive oxygen species (ROS) generated by photoexcitation, especially superoxide species. Here, we propose a strategy of Ce3+ doping in perovskite QDs to guide superoxide species for photocatalytic oxidation reactions. In C(sp3)-H bond oxidation of hydrocarbons, superoxide species were rapidly generated and efficiently utilized on the surface of perovskite QDs, which achieves the stable operation of the catalytic system and obtains a high product conversion rate (15.3 mmol/g/h for benzaldehydes). The mechanism studies show that the strong Ce-oxygen affinity accelerates the relaxation process of photoinduced exciton transfer to superoxide species and inhibits the radiative recombination pathway. This work provides a new idea of utilizing oxygen species on perovskite surface and broadens the design strategy of high-performance QD photocatalysts.

Directly seeding epitaxial growth of tungsten oxides/tungsten diselenide mixed-dimensional heterostructures with excellent optical properties.

Mixed-dimensional heterostructures have drawn significant attention due to their intriguing physical properties and potential applications in electronic and optoelectronic nanodevices. However, limited by the lattice matching, the preparation of heterostructures is experimentally difficult and the underlying growth mechanism has not been well established. Here, we report a three-step seeding epitaxial growth strategy for synthesizing mixed-dimensional heterostructures of one-dimensional microwire (MW) and two-dimensional atomic thin film. Our growth strategy has successfully realized direct epitaxial growth of WSe2 film on WOx MW and significantly improves the quality of the epitaxial WSe2 monolayer, which is evidenced by the remarkably enhanced photoluminescence (PL). More intriguingly, the as-synthesized WOx MWs exhibit a strong nonlinear optical response due to the enhancement effect of the core (WOx)-shell (WSe2) nanocavity. Our work provides a feasible route for direct growth of WOx-based mixed-dimensional heterostructures, which possess potential applications in high-performance optoelectronic devices.