Microwave-Assisted Solvothermal Synthesis and Photocatalytic Activity of Bismuth(III) Based Metal-Organic Framework

This study aims to synthesize and evaluate the photocatalytic activity of bismuth terephthalate material (Bi-BDC) synthesized by solvothermal (ST) and microwave-assisted solvothermal (MW) methods. Differences in the crystal structure and crystal shape were assessed by analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS), N-2 adsorption/desorption, Raman spectrum, and thermal gravimetric analysis (TGA). From XRD, IR, Raman, and XPS results, the fully crystallized Bi-BDC materials were achieved regardless of the preparation router. Bi-BDC-MW exhibited spherical-like morphologies, producing between stacked lamellar, while Bi-BDC-ST method exhibited a heterogeneous structure. The TGA data indicated that Bi-BDC is thermally stable up to 300 degrees C, suggesting the excellent thermal stability of Bi-BDC. The surface area and pore volume of Bi-BDC-MW (18 m(2)/g and 85 x 10(-3) cm(3)/g) are higher than those of Bi-BDC-ST (16 m(2)/g and 52 x 10(-3) cm(3)/g), which is due to its well-defined lamellar microstructure and homogeneity of the crystals. Compared to Bi-BDC-ST, Bi-BDC-MW has a higher value in the content of oxygen vacancy. Moreover, the photocatalytic efficiency of Bi-BDC-MW was significantly higher than that of Bi-BDC-ST, in which 99.44% rhodamine B (RhB) is removed after 360 min of irradiation. The improved photocatalytic efficiency of Bi-BDC-MW is ascribed to the morphology, specific surface area, and oxygen defects, which exhibited the good separation of electrons and holes, as confirmed by the photoluminescence (PL). The results should open a new approach to enhancing the photocatalytic activity of bismuth terephthalate materials.