Nanoconfinement‐Controlled Synthesis of Highly Active, Multinary Nanoplatelet Catalysts from Lamellar Magic‐Sized Nanocluster Templates

Magic‐sized semiconductor nanoclusters (MSCs) possessing intermediate stability are promising precursors for synthesizing low‐dimensional nanostructures that cannot be achieved by direct methods. However, uncontrolled diffusion of MSCs in their colloidal‐state poses challenges in utilizing them as precursors and/or templates for the controlled synthesis of nanomaterials. Herein, a nanoconfined diffusion‐limited strategy to synthesize large CdSe nanoplatelets through the solid‐state transformation of (CdSe)13 MSCs is designed, wherein MSCs serve as both precursors and lamellar bilayer templates. In sharp contrast, in the colloidal‐state, these MSCs are grown to CdSe nanoribbons or nanorods. Furthermore, the nanoconfined route is used not only to transform (CdSe)13, Mn2+:(CdSe)13, and Mn2+:(Cd1−xZnxSe)13 MSCs but also to dope Cu+, producing Cu+:CdSe, Mn2+/Cu+:CdSe, Mn2+/Cu+:Cd1−xZnxSe nanoplatelets, respectively. The resulting multinary nanoplatelets with controlled compositions exhibit unique optical and magneto‐optical properties through characteristic exciton transfer mechanisms. Furthermore, synergistic effects have made quinary Mn2+/Cu+:Cd0.5Zn0.5Se nanoplatelets efficient and reusable catalysts for chemical fixation of CO2 with epoxide (turnover frequency: ≈200/h) under mild conditions. This nanoconfined synthetic strategy paves the way to synthesize diverse shape‐controlled multi‐component nanostructures for optoelectronic and other catalytic applications.