Impact of Peptide‐Based Supramolecular Gels on the Passivation and Optical Properties of CsPbBr ₃ Nanocrystals for Photocatalytic Dye Degradation in Water

Abstract The instability of halide perovskite nanocrystals (PNCs) upon exposure to water is a longstanding problem that has limited the full potential of these materials. Here, this issue is assessed from the point of view of supramolecular chemistry. This approach triggers the self‐assembly of low molecular weight gelators (LMWGs) at the point of the synthesis of PNCs for their simultaneous incorporation into the supramolecular gel formed by those. Thus, a library of peptide‐based molecules is designed which can replace oleyl amine in the synthesis of CsPbBr 3 PNCs via the Hot Injection procedure. In situ gelation is achieved during the synthesis process and the impact of self‐assembly on the water durability of the PNCs is studied. The photocatalytic activity of the most stable PNCs is established by measuring the ability of these materials to degrade Rhodamine B in water. In addition, the self‐assembled peptide network is efficient to prevent lead leaching in water substantially eliminating the lead contamination by the catalyst. Moreover, completely degraded perovskite material can self‐heal to a certain extent within the matrix to revert to its primitive perovskite phase. Altogether, these results open a new way for the use of LMWGs to improve the (re)usability of halide perovskite materials.