Enhancing the photocatalytic efficiency and stability of CsPbBr3 nanocrystals for visible-light driven aerobic diaryl thio/seleno etherification

Abstract

CsPbBr₃ holds promise as a visible light photocatalyst, but its instability in oxygen-rich and polar solvent environments poses a significant challenge for practical utilization. This study demonstrates the effectiveness of orthorhombic CsPbBr₃ nanocrystals (NCs) synthesized from dibromoisocyanuric acid. These NCs exhibit high efficiency as heterogeneous visible light photocatalysts (450–470 nm, 5 mol%) in a template-free aerobic thio/seleno etherification reaction involving 1,3,5-trimethoxybenzene, employing diaryl sulfides and diaryl selenides in acetonitrile (ε ∼ 37.5). A novel surface treatment approach is proposed, utilizing electron-rich 1,3,5-trimethoxybenzene as a reactant to stabilize CsPbBr₃ NCs in situ and address stability challenges in polar solvents and open-air environments. Additionally, among the four systems, the bromide-enriched orthorhombic CsPbBr₃ NCs exhibit markedly enhanced photocatalytic efficiency and stability compared to the cubic systems. The orthorhombic CsPbBr₃ NCs, with prolonged excited state lifetime, promote efficient electron transfer, leading to the generation of superoxide radical anions from the conduction band. These findings highlight the potential of perovskite nanocrystals and provide insights into their applications as visible light photocatalysts in organic transformations.