The prototypical toxic dye rhodamine B (RhB) is perhaps one of the most abundant pollutants in industrial wastewater. Its efficient photocatalytic degradation through composite photocatalysts is crucial for environmental remediation. Here, we synthesized quaternary Bi5O7I/Bi(IO3)3/Bi2(IO4)(IO3)3/BiOIO3 bismuth iodate composites through facile hydrothermal and solvothermal methods. The coexistence of multiple bismuth iodate phases was confirmed by x-ray diffraction analysis, room temperature Raman, and Fourier-transform infrared spectroscopy. The desired chemical states of Bi, I, and O inside the composites were confirmed by x-ray photoelectron spectroscopy. Field emission electron microscopy revealed flower-shaped nanosheet morphology for the composite synthesized at 120 °C, whereas randomly shaped nanoparticles with an average size of 80 nm were formed in the composite calcined at 400 °C. High-resolution transmission electron microscopy further corroborated the existence of multiple phases in the composites. The diffuse reflectance spectroscopy confirmed the optical absorption edges of the composites to be located within the visible range of 1.68–3.16 eV. The flower-shaped quaternary bismuth iodate composite demonstrated 100% degradation of RhB dye within 40 min of optical exposure. This quaternary bismuth iodate composite is suitable for solar harvesting-driven toxic dye remediation.
