Rapid Synthesis of Bismuth MOF @Carbon Nanotube Composite by microwave-assisted Solvothermal for Photodegrading RhB

Abstract

We synthesized a bismuth-MOFs@CNTs (BiBTC@CNTs) catalyst using a microwave-assisted solvothermal method. The mass ratios of CNTs and BiBTC varied from 0 to 2, 5, and 10% (denoted as BiBTC@CNTs-x, x = 0 to 2, 5, and 10). The characteristics of the catalyst were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (UV-Vis DRS). The catalytic activity of the material was tested by photodegradation of rhodamine B. The structure of BiBTC@CNTs-x displayed a UU-200 and CNT structure with rod-shaped interweaving between the CNT fibers. The results indicated that BiBTC@CNTs-2 had the most significant ability to degrade RhB, achieving 98% degradation in 180 min. The increased separation of electron-hole pairs via a built-in electric field between CNT and BiBTC is responsible for the improved photocatalytic degradation of RhB, as observed in the XPS spectrum, transient photocurrent response, electrochemical impedance spectroscopy (EIS), and Mott-Schottky plots. In addition, the catalyst mass, dye concentration, pH of the medium, and radical scavengers were investigated. Furthermore, free radicals (O²⁻) and electrons (e-) played the primary and most influential role in the photocatalytic degradation of both dyes, with a minor contribution from the photogenerated holes (h+). Kinetic study of the dye degradation process followed a first-order kinetic model.