Selective oxidative coupling of amines through light-activated bismuth halide perovskites

Abstract

[EN] Bismuth halide perovskites have emerged as promising alternatives for sustainable and efficient photocatalysts for light-induced organic transformations. Caesium bismuth halide perovskites (Cs3Bi2(ClxBr1-x)9) with different ratios of chloride and bromide were synthesised using a one-step solution process. These perovskites were then employed as photocatalysts for the photocatalytic oxidative coupling of benzylamine (BZA) to produce N-benzylidenebenzylamine (BZI) under ultraviolet-visible light radiation at ambient conditions. The incorporation of bromide ions into the chloride-based perovskite resulted in a noticeable reduction in the bandgap, leading to an enhancement in the photocatalytic activity. Conversely, the addition of chloride ions within the bromide-based perovskite was found to be beneficial for the material's photostability while simultaneously maintaining its high photocatalytic activity. The optimal compromise between the stability and photocatalytic activity for the BZI production was achieved using Cs3Bi2(Cl0.8Br0.2)9, being attained a total BZA conversion and the maximum BZI production with 100 % of selectivity after 6 hours of irradiation. The efficiency of this photocatalyst was ascribed to the highest current density observed during the photocurrent experiments, which improves the charge carrier mobility of the resulting material.