Hydrothermal synthesis of stable lead-free Cs4MnBi2Cl12 perovskite single crystals for efficient photocatalytic degradation of organic pollutants

Abstract

Recently, the photocatalytic degradation of organic pollutants using halide perovskite materials has increasingly attracted people's attention. However, the stability issues and the lead toxicity of such materials cast a shadow over their practical applications. In this study, we successfully synthesized non-toxic Cs₄MnBi₂Cl₁₂ single crystals (SCs) using a hydrothermal method. Joint experiment–theory characterizations reveal the good stability of Cs₄MnBi₂Cl₁₂. Furthermore, the application of Cs₄MnBi₂Cl₁₂ as a photocatalyst in the degradation of organic pollutants was demonstrated for the first time. In detail, rhodamine B (RhB), methylene blue and Sudan Red III dissolved in ethanol can be degraded and decolorized by Cs₄MnBi₂Cl₁₂ SCs under light irradiation. About 97% RhB can be degraded in 7 min, and the degradation efficiency is hardly decreased over ten cycles. Besides, the photocatalytic degradation mechanisms were studied, and the results show that the superoxide (˙O₂⁻) plays a leading role in the photocatalytic process. The degradation pathways of organic pollutants were subsequently analyzed by high-performance liquid chromatography–mass spectrometry, involving three stages of N-deethylation, ring opening, and mineralization. Encouraged by the remarkable structural and optical stability of Cs₄MnBi₂Cl₁₂ SCs, such lead-free perovskite materials may have broad application prospects in the field of photocatalysis.