Engineering Water Stable Perovskite and Plasmonic‐Perovskite Nanocomposites: A Step toward Unleashing the True Potential of Perovskite Catalysis

Abstract Despite garnering so much research interest, the potential technological developments of perovskites are limited due to instability in polar solvents. Here, it is discovered that upon exposure ethanol, initial cubic cesium lead bromide nanocrystals (CsPbBr 3 NCs) undergo a phase transformation from orthorhombic phase. Further water leads formation CsPbBr perovskite nanoaggregates, which shows higher stability compared pristine NCs. A systematic investigation interfaces using various spectroscopic techniques demonstrating self‐assembly process and presented. The increased ethanol‐treated NCs attributed ethoxide ions adsorption on interface, owing strong affinity alkoxide Pb 2+ . Effective surface passivation enhanced charge‐carrier separation, prerequisite an effective photocatalyst. Ethoxide‐stabilized utilized reduce Au 3+ 0 synthesize water‐stable Au‐CsPbBr nanocomposites. hybrid plasmonic metal‐perovskites nanocomposite influences perovskite's excited state charge carrier dynamics. This opens possibilities utilizing synergistic effects light‐harvesting properties nanomaterials with catalytic attributes materials controlling interface by tuning plasmon–exciton coupling.