Water-Stable Perovskite Nanocrystals to Overcome the Photocatalysis–Stability Trade-Off in Aqueous Photo-RAFT Polymerization

Abstract

Metal halide perovskite nanocrystals (PNCs) have demonstrated remarkable photocatalytic properties in diverse photochemical reactions owing to their high absorption coefficients and long photogenerated carrier lifetimes. However, their catalytic applications have been severely hindered by their structural incompatibility with polar solvents, water in particular, due to the labile ionic nature of the perovskite. Realization of the photocatalytic performance of PNCs in an aqueous medium would significantly expand their potential in photocatalysis. Herein, judiciously designed CsPbBr₃ NCs stabilized on Al₂O₃ nanoflowers (denoted as A-CsPbBr₃ NCs) are utilized as water-stable photocatalysts for aqueous photomediated reversible addition–fragmentation chain transfer (photo-RAFT) polymerization. The A-CsPbBr₃ NCs exhibited exceptional water stability and photostability owing to the stabilization effect endowed by Al₂O₃ nanoflowers without sacrificing their charge/carrier transport properties. Consequently, aqueous photo-RAFT polymerization was successfully performed by leveraging A-CsPbBr₃ NCs as photocatalysts under visible light illumination, which was inaccessible to conventional short-ligand-capped PNCs. The effects of the excitation wavelength, catalyst loading, and architectures of PNCs on the visible-light-mediated polymerization were scrutinized to reveal the polymerization via a photoinduced electron-/energy-transfer mechanism, yielding polymers/copolymers with well-defined compositions, well-controlled molecular weights, low polydispersity, and high chain-end fidelity.