Bromoacetyl Bromide‐Derived CsPbBr <sub>3</sub> Quantum Dots: Robust Water Stability for Aqueous‐Phase Photocatalysis
Bikram Gurung, Jeong‐Hyeon Park, Minwoo Jeong, Jaegwan Jung, Debasish Borah, Reginold Renzong Lepcha, Shivanand Chettri, Sagarmani Rasaily, Sohee Jeong, Anand Pariyar, Yong‐Hyun Kim, Sudarsan Tamang
Abstract
Abstract Cesium lead bromide (CsPbBr 3 ) perovskites are promising photocatalysts for organic transformations, offering a cost‐effective and recyclable alternative to conventional catalysts. However, their scope is limited to nonpolar solvents due to instability in aqueous environments. Here, bromoacetyl bromide (BABr) as a novel precursor for the one‐step synthesis of highly water stable, size‐controlled CsPbBr 3 quantum dots (QDs), is introduced. BABr reacts with oleylamine (OAm) to generate bromide ions for crystallization while forming a unique passivating ligand, [ 2 ‐bromo‐ N ‐(octadec‐ 9 ‐en‐ 1 ‐yl) acetamide] (BOAM), which strongly coordinates to the QD surface via a carbonyl C─O group and a sacrificial bromine atom, as confirmed by FTIR, NMR, XPS, and DFT studies. This strategy yields high‐quality size‐tunable (emission ≈475–521 nm, PLQY ≈95–100%) CsPbBr 3 QDs at mild temperatures (≈60–140 °C). Additionally, the protonated polar amide group in the ligand imparts a positive zeta potential (+56 mV), ensuring high dispersibility and unprecedented stability (>2 months, photoluminescence (PL) retention ≈78%) in aqueous media. Leveraging this, the first example of CsPbBr 3 QDs as recyclable photocatalysts for the azide‐alkyne “click reaction” in water under visible light, achieving ≈100% yields at room temperature is demonstrated. Combining synthetic simplicity, mechanistic insights, and functional demonstration, this work paves the way for aqueous‐phase photocatalysis with CsPbBr 3 perovskite QDs.