In‐Situ Anchoring Pb‐Free Cs3Bi2Br9@BiOBr Quantum Dots on NHx‐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 Cs3Bi2Br9@BiOBr perovskite QDs were anchored on the surface of NHx‐rich monodisperse silica (A−SiO2) via N−Bi chemical bonding to isolate QDs from each other, thus enhancing efficient surface passivation and suppressing optical decay. Compared to unanchored QDs, Cs3Bi2Br9@BiOBr QDs/A−SiO2 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(sp3)−H bond activation and demonstrated astonishing conversion rates (4317 μmol g−1 h−1) with high selectivity (around 87 %). [ABSTRACT FROM AUTHOR]