In-Situ Anchoring Pb-Free Cs 3 Bi 2 Br 9 @BiOBr Quantum Dots on NH x -Rich Silica with Enhanced Blue Emission and Satisfactory Stability for Photocatalytic Toluene Oxidation.

All-inorganic metal halide perovskite quantum dots (QDs) have attracted attention from researchers with their fascinating optoelectronic properties. However, blue-emitting perovskite QDs typically have low photoluminescence quantum yield (PLQY). For potential commercial applications, it is preferable to replace Pb with an element having low toxicity. Here, Pb-free Cs 3 Bi 2 Br 9 @BiOBr perovskite QDs were anchored on the surface of NH x -rich monodisperse silica (A-SiO 2 ) via N-Bi chemical bonding to isolate QDs from each other, thus enhancing efficient surface passivation and suppressing optical decay. Compared to unanchored QDs, Cs 3 Bi 2 Br 9 @BiOBr QDs/A-SiO 2 composites exhibited significantly enhanced blue emission performance, the PLQY of which increased from 16.62 % to 77.26 %, in addition to good water and environmental stability. Finally, the novel composites as photocatalysts were used to drive the oxidation of toluene, a template reaction of C(sp 3 )-H bond activation and demonstrated astonishing conversion rates (4317 μmol g -1  h -1 ) with high selectivity (around 87 %).