Catalytic Versatility of Lead-Free Cu2+-Doped Cs2AgBiCl6 Double Perovskite in Sustainable Photocatalysis and Quinazoline Synthesis

In this report, we present a sustainable, all-inorganic, lead-free double perovskite, Cu²⁺-doped Cs₂AgBiCl₆ (CABC X), designed by using a simple chemical reflux approach. This material features an octahedral morphology and is explored for the first time as a heterogeneous catalyst in the photocatalytic oxidation of benzyl alcohol to aromatic aldehyde. Benzyl alcohol oxidation serves as a model reaction to investigate the impact of Cu²⁺ doping on Cs₂AgBiCl₆, alongside the photocatalytic reduction of nitroaromatics to aniline, unfolding its versatility in various catalytic processes. Additionally, the CABC X perovskite catalyst has been investigated for the synthesis of several pharmaceutically important quinazoline moieties, yielding excellent results. The catalytic protocols are highly sustainable and applicable to a wide range of substrates of respective catalytic reactions with a high yield of products. Photoluminescence studies reveal that as the molar concentrations of the Cu²⁺ dopant increase, the fluorescence intensity of the double perovskite decreases. This trend indicates reduced recombination and better charge separation from X = 0 to X = 30 mmol % Cu²⁺ dopant concentration, contributing to the enhanced photocatalytic activity. Structural and compositional details of the synthesized lead-free perovskite were confirmed through scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, EDX, and X-ray photoelectron spectroscopy studies, while thermal stability was assessed via thermogravimetric analysis. Our findings demonstrate an effective strategy for tuning the photophysical properties of Cs₂AgBiCl₆ through transition-metal doping, thereby expanding its applications in catalysis.