Flower-Like BiOI Microspheres Decorated with Plasmonic Gold Nanoparticles for Dual Detoxification of Organic and Inorganic Water Pollutants

The development of bismuth-based photocatalysts in response to emerging demand for solving environmental problems has attracted immense interest over the past few years. This is owed to their low cost, nontoxicity, and high stability. Here, we report the synthesis of a nanohybrid consisting of 3D flower-like BiOI microspheres decorated with plasmonic gold nanoparticles (∼15 nm) to experience enhanced photocatalytic activity. Various characterization tools such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) have been used to investigate the morphology and crystallinity of the photocatalyst. The formation of the nanohybrid by the gold nanoparticles and BiOI microspheres has been confirmed by Raman as well as picosecond resolved ultrafast spectroscopy. The as-synthesized nanohybrid exhibits a superior photocatalytic activity toward the detoxification of organic (methyl orange) as well as inorganic (hexavalent chromium) water pollutants under visible and red light (λ > 600 nm) irradiation. Our detailed ultrafast spectroscopic studies link the enhanced photocatalytic activity of the nanohybrid to an improved charge carrier separation in the metal–semiconductor interface. In addition, we find that the degradation process of the dye and the reduction of hexavalent chromium [Cr(VI)] are based on two completely different mechanisms. Moreover, our synthesized nanohybrid efficiently retains its activity as well as its structural stability after several cycles of light irradiation, which highlights it as a promising candidate for environmental remediation.