Synthesis of adjustable {312}/{004} facet heterojunction MWCNTs/Bi5O7I photocatalyst for ofloxacin degradation: Novel insights into the charge carriers transport

Direct Z-scheme Cu2O/WO3/TiO2 nanocomposite as a potential supercapacitor electrode and an effective visible-light-driven photocatalyst

This paper presents the synthesis of visible light-responsive ternary nanocomposites composed of cuprous oxide (Cu2O), tungsten trioxide (WO3), and titanium dioxide (TiO2) with varying weight percentages (wt.%) of the Cu2O. The resulting Cu2O/WO3/TiO2 (CWT) nanocomposites exhibited band gap energy ranging from 2.35 to 2.90 eV. Electrochemical and photoelectrochemical (PEC) studies confirmed a reduced recombination rate of photoexcited charge carriers in the CWT nanocomposites, facilitated by a direct Z-scheme heterojunction. The 0.50CWT nanocomposite demonstrated superior photodegradation activity (2.29 × 10-2 min-1) against Reactive Black 5 (RB5) dye under visible light activation. Furthermore, the 0.50CWT nanocomposite exhibited excellent stability with 80.51% RB5 photodegradation retention after five cycles. The 0.50CWT electrode achieved a maximum specific capacitance of 66.32 F/g at 10 mA/g current density, with a capacitance retention of 95.17% after 1000 charge-discharge cycles, affirming its stable and efficient supercapacitor performance. This was supported by well-defined peaks in cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves, indicating pseudocapacitive properties.

In situ construction of Ag/Bi2O3/Bi5O7I heterojunction with Bi-MOF for enhance the photocatalytic efficiency of bisphenol A by facet-coupling and s-scheme structure

In this study, Ag/Bi2O3/Bi5O7I with s-scheme heterostructures were successfully synthesized in situ by nano-silver modification of CUA-17 and halogenated hydrolysis.The growth rate of Bi2O3 crystals was effectively controlled by adjusting the doping amount of Ag, resulting in the formation of a facet-coupling heterojunctions. Through the investigation of the microstructure and compositional of catalysts, it has been confirmed that an intimate facet coupling between the Bi2O3 (120) facet and the Bi5O7I (312) facet, which provides robust support for charge transfer. Under visible light irradiation, the AgBOI.3 heterojunction photocatalyst exhibited an outstanding degradation rate of 98.2% for Bisphenol A (BPA) with excellent stability. Further characterization using optical, electrochemical, impedance spectroscopy, and electron spin resonance techniques revealed significantly enhanced efficiency in photogenerated charge separation and transfer, and confirming the s-scheme structure of the photocatalyst. Density functional theory calculations was employed to elucidate the mechanism of BPA degradation and the degradation pathway of BPA was investigated by LC-MS. Finally, the toxicity of the degradation intermediates was evaluated using T.E.S.T software.

Synthesis of 3D Sb2O3-based heterojunction reinforced by SPR effect and photo-Fenton mechanism for upgraded oxidation of metronidazole in water environments

The traditional homogenous and heterogenous Fenton reactions have frequently been restrained by the lower production of Fe2+ ions, which significantly obstructs the generation of hydroxyl radicals from the decomposition of H2O2. Thus, we introduce novel photo-Fenton-assisted plasmonic heterojunctions by immobilizing Fe3O4 and Bi nanoparticles onto 3D Sb2O3 via co-precipitation and solvothermal approaches. The ternary Sb2O3/Fe3O4/Bi composites offered boosted photo-Fenton behavior with a metronidazole (MNZ) oxidation efficiency of 92% within 60 min. Among all composites, the Sb2O3/Fe3O4/Bi-5% hybrid exhibited an optimum photo-Fenton MNZ reaction constant of 0.03682 min- 1, which is 5.03 and 2.39 times higher than pure Sb2O3 and Sb2O3/Fe3O4, respectively. The upgraded oxidation activity was connected to the complementary outcomes between the photo-Fenton behavior of Sb2O3/Fe3O4 and the plasmonic effect of Bi NPs. The regular assembly of Fe3O4 and Bi NPs enhances the surface area and stability of Sb2O3/Fe3O4/Bi. Moreover, the limited absorption spectra of Sb2O3 were extended into solar radiation by the Fe3+ defect of Fe3O4 NPs and the surface plasmon resonance (SPR) effect of Bi NPs. The photo-Fenton mechanism suggests that the co-existence of Fe3O4/Bi NPs acts as electron acceptor/donor, respectively, which reduces recombination losses, prolongs the lifetime of photocarriers, and produces more reactive species, stimulating the overall photo-Fenton reactions. On the other hand, the photo-Fenton activity of MNZ antibiotics was optimized under different experimental conditions, including catalyst loading, solution pH, initial MNZ concentrations, anions, and real water environments. Besides, the trapping outcomes verified the vital participation of •OH, h+, and •O2- in the MNZ destruction over Sb2O3/Fe3O4/Bi-5%. In summary, this work excites novel perspectives in developing boosted photosystems through integrating the photocatalysis power with both Fenton reactions and the SPR effects of plasmonic materials.

Design and construction of a robust ternary Bi5O7I/Cd0.5Zn0.5S/CuO photocatalytic system for boosted photodegradation of antibiotics via dual-S-scheme mechanisms: Environmental factors and degradation intermediates

The detection of efficacious and environment-friendly nanomaterials with prominent photocatalytic performance is crucial for the detoxification of antibiotics in wastewater. Herein, a dual-S-scheme Bi5O7I/Cd0.5Zn0.5S/CuO semiconductor was designed and fabricated via a simple approach to degrade tetracycline (TC) and other types of antibiotics under LED illumination. However, Cd0.5Zn0.5S and CuO nanoparticles were decorated on the surface of the Bi5O7I microsphere to create a dual-S-scheme system that stimulates visible-light utilization and facilitates the dissolution of excited photo-curriers. Therefore, the Bi5O7I/Cd0.5Zn0.5S/CuO system offers strong redox ability, which reflects reinforced photocatalytic activity and robust stability. The ternary heterojunction discloses enhanced TC detoxification efficiency of 92% in 60 min with TC destruction rate constant of 0.04034 min-1, outperforming pure Bi5O7I, Cd0.5Zn0.5S, and CuO by 4.27, 3.20, and 4.80 folds, respectively. Besides, Bi5O7I/Cd0.5Zn0.5S/CuO manifests outstanding photo-activity against a series of antibiotics like norfloxacin, enrofloxacin, ciprofloxacin, and levofloxacin under the same operational conditions. The active species detection, TC destruction pathways, catalyst stability, and photoreaction mechanisms of Bi5O7I/Cd0.5Zn0.5S/CuO were accurately explained in detail. Summarily, this work introduces a new class of dual-S-scheme system with strengthened catalytic properties to effectively eliminate the antibiotics in wastewater under visible-light illumination.

Photoluminescence and Photocatalytic Properties of MWNTs Decorated with Fe-Doped ZnO Nanoparticles

The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were evidenced by X-ray diffraction (XRD). X-ray Photoelectron spectroscopy (XPS) revealed the presence of both 2+ and 3+ valence states of Fe ions in a ratio of approximately 0.5. The electron paramagnetic resonance EPR spectroscopy sustained the presence of Fe³⁺ ions in the ZnO lattice and evidenced oxygen vacancies. Transmission electron microscopy (TEM) images showed the attachment and distribution of Fe-doped ZnO nanoparticles along the nanotubes with a star-like shape. All of the samples exhibited absorption in the UV region, and the absorption edge was shifted toward a higher wavelength after the addition of MWCNT component. The photoluminescence emission spectra showed peaks in the UV and visible region. Visible emissions are a result of the presence of defects or impurity states in the material. All of the samples showed photocatalytic activity against the Rhodamine B (RhB) synthetic solution under UV irradiation. The best performance was obtained using the MWCNT:ZnO-Fe(1:5) nanocomposite samples, which exhibited a 96% degradation efficiency. The mechanism of photocatalytic activity was explained based on the reactive oxygen species generated by the nanocomposites under UV irradiation in correlation with the structural and optical information obtained in this study.

Recent Advances in Carbon-Based Materials for Adsorptive and Photocatalytic Antibiotic Removal

Antibiotics have been a primary environmental concern due to their widespread dispersion, harmful bioaccumulation, and resistance to mineralization. Unfortunately, typical processes in wastewater treatment plants are insufficient for complete antibiotic removal, and their derivatives in effluent can pose a threat to human health and aquatic communities. Adsorption and photocatalysis are proven to be the most commonly used and promising tertiary treatment methods. Carbon-based materials, especially those based on graphene, carbon nanotube, biochar, and hierarchical porous carbon, have attracted much attention in antibiotic removal as green adsorbents and photocatalysts because of their availability, unique pore structures, and superior physicochemical properties. This review provides an overview of the characteristics of the four most commonly used carbonaceous materials and their applications in antibiotic removal via adsorption and photodegradation, and the preparation of carbonaceous materials and remediation properties regarding target contaminants are clarified. Meanwhile, the fundamental adsorption and photodegradation mechanisms and influencing factors are summarized. Finally, existing problems and future research needs are put forward. This work is expected to inspire subsequent research in carbon-based adsorbent and photocatalyst design, particularly for antibiotics removal.