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

Abstract

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 fullspectrum 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 Ag 3 PO 4 alone, the narrow bandgap of BiO 2−x /Ag 3 PO 4 /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 /Ag 3 PO 4 /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.

Ag3PO4/NiO Composites with Enhanced Photocatalytic Activity under Visible Light

“…Moreover, the characteristic peaks of Ag 3 PO 4 in the Ag 3 PO 4 /NiO composites are slightly shifted, primarily for AgNi25, AgNi50, and AgNi75, which can be attributed to the interaction between the Ag 3 PO 4 and NiO phases. 15 , 39 , 40 …”

“…Moreover, the characteristic peaks of Ag 3 PO 4 in the Ag 3 PO 4 /NiO composites are slightly shifted, primarily for AgNi25, AgNi50, and AgNi75, which can be attributed to the interaction between the Ag 3 PO 4 and NiO phases. 15,39,40 The Raman spectra obtained for all samples are shown in Figure 3b. According to first-principles calculations previously published, 34 Ag 3 PO 4 presents a total of 18 Raman-active modes; however, in this work, only five Raman-active modes were identified, all related to [PO 4 ] clusters.…”

“…Among the composites, AgNi75 showed the lowest band gap (E gap = 1.7 eV), probably associated with the introduction of surface defects caused by the greater amount of NiO during the in situ precipitation of Ag 3 PO 4 , which can lead to a strong interaction between semiconductors, facilitating the formation of an interaction between the NiO and Ag 3 PO 4 phases. 28,40 Morphological Aspects. The morphologies of the pure samples and Ag 3 PO 4 /NiO composites were investigated by showing the delimited region (white dashed square).…”

“…The E gap of the Ag 3 PO 4 and NiO samples are in accordance with previous reports. ,,,, The band gap of the composites narrowed slightly as compared to that of Ag 3 PO 4 with enhanced light absorption. Among the composites, AgNi75 showed the lowest band gap ( E gap = 1.7 eV), probably associated with the introduction of surface defects caused by the greater amount of NiO during the in situ precipitation of Ag 3 PO 4 , which can lead to a strong interaction between semiconductors, facilitating the formation of an interaction between the NiO and Ag 3 PO 4 phases. , …”

ZnO Photocatalyst Revisited: Effective Photocatalytic Degradation of Emerging Contaminants Using S-Doped ZnO Nanoparticles under Visible Light Radiation

“…Today, the world is facing a lot of water shortage and pollution. − With the advancement of science and technology, demands have increased for dyes and pigmentation; nonetheless, numerous waste dyes used in various industries are entering rivers and seas as wastewaters. − A large amount of industrial wastewaters is colored because a variety of industries including cosmetics, food, coloring, and textiles dispose their waste colors into water. − Many industrial dyes are not directly toxic, but they produce carcinogenic compounds, such as aromatic amines, during anaerobic degradation. − Although most of these materials are naturally decomposed, the importance of using efficient and economical methods to eliminate contaminants is evident. − …”