Solvothermal Synthesis of Bismuth-Based Halide Perovskite Nanostructures for Photocatalytic Degradation of Organic Pollutants under LED Light Irradiation

Abstract

The use of bismuth-based halide perovskites for photocatalysis has attracted increasing attention because of their matching photoelectric properties and the nontoxicity of bismuth metal. However, organic–inorganic halide perovskites with chloride as halides possess a large band gap, restricting their potential use in visible-light-activated photocatalytic processes. In this study, a bismuth-based halide perovskite nanostructure, tris(tetramethylammonium) nonachlorodibismuthate (((CH3)4N)3Bi2Cl9), has been successfully synthesized through a solvothermal process using a mixture of dichloromethane/N,N-dimethylformamide as both solvent and reagent. The results show that, when dichloromethane and N,N-dimethylformamide are combined simultaneously during synthesis, Bi-based halide perovskite nanostructures are formed with a reduced midgap-state-induced energy gap. The formation of ((CH3)4N)3Bi2Cl9 was confirmed through X-ray diffraction patterns and Fourier transform-infrared spectroscopy. The presence of localized states extended in the band gap (referred to as midgap states) was demonstrated by ultraviolet–visible diffuse reflectance and photoluminescence spectroscopy. The ((CH3)4N)3Bi2Cl9 samples exhibit super photocatalytic activity for Rhodamine B and tetracycline hydrochloride degradation in an aqueous solution under visible-light irradiation. The bismuth halide perovskite (BHP-30-30 sample) exhibited a Rhodamine B degradation efficiency of 99.4% in 30 min and a tetracycline hydrochloride degradation efficiency of 78.4% in 3 h. The fact that this catalyst is recyclable four times further demonstrates the promise of BHP-30-30 as a replacement visible-light-sensitive catalyst for removing organic pollutants.