3D‐cavity‐confined CsPbBr3 quantum dots for visible‐light‐driven photocatalytic C(sp3)–H bond activation

Metal halide perovskite (MHP) quantum dots (QDs) offer immense potential for several areas of photonics research due to their easy and low‐cost fabrication and excellent optoelectronic properties. However, practical applications of MHP QDs are limited by their poor stability and, in particular, their tendency to aggregate. Here, we develop a two‐step double‐solvent strategy to grow and confine CsPbBr3 QDs within the three‐dimensional (3D) cavities of a mesoporous SBA‐16 silica scaffold (CsPbBr3@SBA‐16). Strong confinement and separation of the MHP QDs lead to a relatively uniform size distribution, narrow luminescence, and good ambient stability over 2 months. In addition, the CsPbBr3@SBA‐16 presents a high activity and stability for visible‐light‐driven photocatalytic toluene C(sp3)–H bond activation to produce benzaldehyde with ∼730 µmol g−1 h−1 yield rate and near‐unity selectivity. Similarly, the structural stability of CsPbBr3@SBA‐16 QDs is superior to that of both pure CsPbBr3 QDs and those confined in MCM‐41 with 1D channels.