Chemically modified amino porphyrin/TiO2 for the degradation of Acid Black 1 under day light illumination

Synthesis and characterization of Co(II) porphyrin complex supported on chitosan/graphene oxide nanocomposite for efficient green oxidation and removal of Acid Orange 7 dye

Catalytic degradation of Acid Orange 7 (AO7) by hydrogen peroxide in an aqueous solution has been investigated using cobalt(II) complex of 5, 10, 15, 20 Tetrakis [4-(hydroxy)phenyl] porphyrin [Co(II) TPHPP] covalently supported chitosan/Graphene Oxide nanocomposite [Co(II) TPHPP]-Cs/GO, as highly efficient and recoverable heterogeneous catalyst. The structures and properties of [Co(II) TPHPP]-Cs/GO nanocomposite were characterized by techniques such as UV-Vis, FT-IR, SEM, EDX, TEM, and XRD. The oxidation reaction was followed by recording the UV-Vis spectra of the reaction mixture with time at λmax = 485 nm. [Co(II) TPHPP]-Cs/GO nanocomposite demonstrated high catalytic activity and could decompose 94% of AO7 within 60 min. The factors that may influence the oxidation of Acid Orange 7, such as the effect of reaction temperature, pH, concentration of catalyst, Acid Orange 7, and hydrogen peroxide, have been studied. The results of total organic carbon analysis (TOC) showed 50% of dye mineralization under mild reaction conditions of AO7 (1.42 × 10-4M) with H2O2 (8 × 10-2M) in the presence of [Co(II) TPHPP]-Cs/GO nanocomposite (15 × 10-3 g/ml) and pH = 9 at 40 °C. The reuse and stability of the nanocomposite were examined and remarkably, even after six cycles of reuse, there was no significant degradation or deactivation of the recycled catalyst. Residual organic compounds in the reaction mixture were identified by using GC-MS analyses. The radical scavenging measurements and photoluminescence probing technology of disodium salt of terephthalic acid indicated the formation of the hydroxyl radical as the reactive oxygen species in the [Co(II) TPHPP]-Cs/GO nanocomposite/H2O2 system. A mechanism for the oxidation reaction has been discussed.

Surface Modification of ZnO with Sn(IV)-Porphyrin for Enhanced Visible Light Photocatalytic Degradation of Amaranth Dye

Two hybrid composite photocatalysts, denoted as SnP/AA@ZnO and SnP@ZnO, were fabricated by a reaction of trans-dihydroxo[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV) (SnP) and ZnO with and without pretreatment of adipic acid (AA), respectively. In SnP@ZnO, SnP and ZnO are likely held together by a coordinative interaction between the pyridyl N atoms of SnP and the Zn atoms on the surface of ZnO. In the case of SnP/AA@ZnO, the SnP centers were robustly coupled with ZnO nanoparticles through the AA anchors. SnP/AA@ZnO exhibited largely enhanced photocatalytic activities for the degradation of anionic amaranth (AM) dye under a visible light irradiation, compared to SnP, ZnO, and SnP@ZnO. The degradation efficiency of AM by SnP/AA@ZnO was 95% within 60 min at a rate constant of 0.048 min-1. The remarkable photocatalytic oxidation performance of SnP/AA@ZnO was mainly attributed to the synergistic effect between SnP and ZnO. This study is valuable for the development of highly effective composite photocatalytic systems in advanced oxidation processes and is of importance for the treatment of wastewater containing dyes.

Solar light-driven CeVO4/ZnO nanoheterojunction for the mineralization of Reactive Orange 4

In this study, we synthesized CeVO₄/ZnO nanoheterojunction photocatalyst through hydrothermal-precipitation method. The prepared photocatalyst was characterized by Fourier transform infrared analysis (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) with elemental color mapping (ECM), high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern, UV-vis diffuse reflection spectroscopy (UV-vis-DRS), BET, and photoluminescence (PL) spectroscopy. The BET surface area of CeVO₄/ZnO is 10.50 m²/g. The photocatalytic activity of CeVO₄/ZnO nanoheterojunction under solar light was investigated for the degradation of Reactive Orange 4 (RO 4). CeVO₄/ZnO has been found to be more effective for mineralization of RO 4 than the prepared ZnO at neutral pH. The addition of TBA (^•OH scavenger) contributes a significant decrease in the photodegradation efficiently of the catalyst. Chemical oxygen demand (COD) measurements confirmed the complete mineralization of RO 4. In addition, it found that the photocatalyst was stable and reusable. Graphical abstract.

Computational Study of Cresyl Violet Covalently Attached to the Silane Coupling Agents: Application to TiO2-Based Photocatalysts and Dye-Sensitized Solar Cells

The covalent attachment of photosensitizing dyes to TiO₂ using silane coupling agents (SCAs) is a promising strategy for enhancing the photocatalytic activity of TiO₂-based photocatalysts and the photovoltaic conversion of dye-sensitized solar cells (DSSCs). This approach can control the geometry and orientation of the photosensitizing dye on the TiO₂ surface. In this study, a density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation was carried out on cresyl violet (CV) covalently attached to SCAs with a terminal oxirane group (OTES–Cn) to reveal the influence of OTES–Cn on the geometry of the photosensitizing dyes. The potential of CV covalently attached to OTES–Cn (CV–OTES–Cn) to act as a photosensitizing dye was also analyzed. The hydroxyl group formed by the epoxy-opening reaction between CV and OTES–Cn strongly influenced the geometry of CV–OTES–Cn, which was attributed to a CH–O interaction. Additionally, TD-DFT, frontier molecular orbital and molecular electrostatic potential calculations revealed that CV–OTES–Cn has excellent optical properties and electron injection ability. In particular, the characteristics of the unbent conformation of CV–OTES–Cn are expected to contribute significantly to the photocurrent in TiO₂-based photocatalysts and DSSCs. These findings enhance the understanding of the covalent attachment strategy using SCAs and contribute to improving TiO₂-based photocatalysts and DSSCs.

Photodegradation of Antibiotics by Noncovalent Porphyrin-Functionalized TiO2 in Water for the Bacterial Antibiotic Resistance Risk Management

Antibiotics represent essential drugs to contrast the insurgence of bacterial infections in humans and animals. Their extensive use in livestock farming, including aquaculture, has improved production performances and food safety. However, their overuse can implicate a risk of water pollution and related antimicrobial resistance. Consequently, innovative strategies for successfully removing antibiotic contaminants have to be advanced to protect human health. Among them, photodegradation TiO₂-driven under solar irradiation appears not only as a promising method, but also a sustainable pathway. Hence, we evaluated several composite TiO₂ powders with H₂TCPP, CuTCPP, ZnTCPP, and SnT4 porphyrin for this scope in order to explore the effect of porphyrins sensitization on titanium dioxide. The synthesis was realized through a fully non-covalent functionalization in water at room conditions. The efficacy of obtained composite materials was also tested in photodegrading oxolinic acid and oxytetracycline in aqueous solution at micromolar concentrations. Under simulated solar irradiation, TiO₂ functionalized with CuTCPP has shown encouraging results in the removal of oxytetracycline from water, by opening the way as new approaches to struggle against antibiotic's pollution and, finally, to represent a new valuable tool of public health.

Synthesis and photocatalytic activity study of S-doped WO3 under visible light irradiation

In this study, a photocatalyst S-doped WO₃ was successfully synthesized by the hydrothermal method. The prepared undoped and S-doped WO₃ samples were then characterized by XRD, SEM, XPS, and UV-vis DRS. The results showed that the band gap energy of S-doped WO₃ was lower than that of the undoped WO_3, which led to a better absorption of visible light. Furthermore, the results of XPS analysis suggested that the doping with S element resulted in an increase in lattice oxygen vacancies on the surface of S-WO₃, which could effectively improve the photocatalytic activity. The photocatalytic performance of the S-WO₃ samples were evaluated by the measurement of methylene blue (MB) degradation under visible light irradiation. The experimental results demonstrated that S-doped WO₃ sample exhibited a much better photodegradation performance compared to undoped WO₃, with the maximum MB removal efficiency of 78.7% for the 5% S-WO₃ sample. Based on the above results, the mechanisms of photodegradation of MB by S-WO₃ were discussed.

A facile synthesis of novel ε-Fe2O3 grafted 2D h-BN nanostructures for enhanced visible active photocatalytic applications

Solvothermally synthesized h-BN/ε-Fe₂O₃ nanocomposite catalyst exhibited enhanced photocatalytic activity compared to bare h-BN and c-BN catalysts.

Photocatalytic and photoelectrocatalytic performance of sonochemically synthesized Cu2O@TiO2 heterojunction nanocomposites

Cu₂O@TiO₂ heterojunction nanocomposites were prepared via ultrasonic method towards the removal of the environmental pollutant of MO by the visible light photocatalytic approach. The structure of prepared Cu₂O@TiO₂ heterojunction nanocomposites was analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, photoluminescence spectroscopy, UV-Visible absorption spectroscopy, diffused reflectance spectroscopy. The photocatalytic degradation ability was tested using methyl orange as a model pollutant. From the observed pseudo-first order reaction, it was clear that Cu₂O@TiO₂ nanocomposites showed enhanced photocatalytic activity (rate = 0.223 s^-1). The formation of demethylated methyl orange as an intermediate was identified from HPLC analysis at a retention time of 3.47 min. When doped with Cu₂O, the TiO₂ preserved the integrity of its structural, revealing the morphology there is no significant changes have been made, favoring photoelectrochemical appliances. In presence of illumination, the photocurrent of Cu₂O@TiO₂ was 4.5 folds greater than that of TiO₂, involving that incorporating with Cu₂O extensively enhanced mobility of electron via reducing the recombination rate of electron-hole pairs.