Oxygen-Vacancy-Rich BiO_2–x/Ag₃PO₄/CNT Composite for Polycyclic Aromatic Hydrocarbons (PAHs) Removal via Visible and Near-Infrared Light Irradiation

The ever-mounting drilling operations in the petroleum industry have been accompanied by a tremendous amount of wasted drilling fluid, polycyclic aromatic hydrocarbons (PAHs), which poses a huge threat to human health and the ecosystem. In this study, a novel oxygen-rich defective photocatalyst with multiheterostructure was fabricated by a two-step deposition, which exhibits impressive photocatalytic activity toward naphthalene and pyrene under full-spectrum irradiation. Fourier transform infrared spectroscopy, Raman shift, and X-ray diffraction analysis were employed to verify the functional group interaction and modification mechanism. The morphology and microstructure of the synthesized composite were investigated using scanning electron microscopy with X-ray mapping system and transmission electron microscopy. Compared with BiO_2–x or Ag₃PO₄ alone, the narrow bandgap of BiO_2–x/Ag₃PO₄/CNT composite could promote the photocatalytic efficiency via enhancing its optical absorption capacity, which was confirmed by the result of UV–vis–NIR diffuse reflection spectra. Prepared BiO_2–x/Ag₃PO₄/CNT composite could remove up to 90% of naphthalene after irradiating for 15 min with visible and near-infrared light. Furthermore, a potential mechanism between the synergy of the photocatalysts was revealed according to the results of the ESR spectra and photoelectrochemical test. This study offers a novel photocatalyst for PAHs removal from wasted drilling fluids by harvesting the full spectrum of solar light.