Lead-free bismuth-based perovskites coupled with g–C3N4: A machine learning based novel approach for visible light induced degradation of pollutants

Abstract

The use of metal halide perovskites in photocatalytic processes has been attempted because of their unique optical properties. In this work, for the first time, Pb-free Bi-based perovskites of the Cs3Bi2X9 type (X = Cl, Br, I, Cl/Br, Cl/I, Br/I) were synthesized and subjected to comprehensive morphological, structural, and surface analyses, and photocatalytic properties in the phenol degradation reaction were examined. Furthermore, the most promising Pb-free Bi-based Cs3Bi2X9 perovskites (i.e., structures that present an optimal combination of structural features and efficiency) were selected using a machine learning based virtual screening methodology and enriched with the C3N4 composite. The selected and designed Cs3Bi2 (Cl/Br)9 structures were in line with the “safe and sustainable by design” approach and applied for the first time in the aforementioned reaction, which allowed for approximately 84% efficiency under visible light. The main merit of this achievement was the optimum deposition of perovskite Cs3Bi2(Cl/Br)9 (5 wt%) on the C3N4 matrix, which resulted in approximately a two-fold increase in the apparent quantum efficiency of the composite compared with that of bare C3N4 (at an excitation wavelength of 430 nm).