Narrow Results

Nanocomposites have many promising applications such as in hyperthermia and photodegradation. Laser ablation-assisted synthesis of nanocomposites offers several advantages such as it is a green synthesis method, cost-effective, ease of handling and absence of any by-products. This study included the fabrication of copper-silicon (Cu-Si) nanocomposites using liquid-phase laser ablation, followed by an investigation into their potential uses in photothermal hyperthermia and photodegradation. The surface properties, chemical composition and crystallinity were examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. Spherical, capsule-like and hexagonal nanoparticles with a size of 28nm were observed from transmission electron microscopy (TEM). The near-infrared (NIR) 808nm laser was used to obtain the optimum photothermal hyperthermia temperature. At increasing concentrations of nanocomposites and operating laser powers, the temperature trend of nanofluid was monitored and revealed a rising trend. Moreover, an increasing trend in degradation efficiency of methylene green dye was observed, with values of 46.4%, 81.7% and 95.7%, corresponding to photocatalyst doses of 10mg, 20mg and 30mg, respectively. These results shed light on the potential application of contamination-free nanocomposites for hyperthermia and photodegradation.

A hexapod-like lead sulphide (PbS) nanostructure with six symmetric arms were investigated by Raman spectrum. The first order longitudinal optical phonons (1–LO) and second order longitudinal optical phonons (2–LO) vibration modes locate at 205 cm^-1 and 456 cm^-1, respectively. The transverse optical ( TO ) mode and combination modes (LO+TO and TO+TA) exist in the low frequency area. In air circumstance, the surface of PbS nanomaterials can be easily damaged by laser with power ~1.2 mW. The vacuum circumstance can avoid from photodegradation efficiently. Therefore, both irradiation by enough power laser and oxygen condition are necessary conditions for the photodegradation of PbS nanomaterials.

In this study, titanium dioxide was synthesized by using a hydrothermal technique at different growth temperatures. The study involved investigating the effects of growth temperature on crystal structure, surface area, morphology, and photocatalytic properties. The results indicated the growth of pure monoclinic titania. Additionally, an increase in growth temperature led to the formation of nanostructures to form nanowires and nanorods from nanospheres. The findings revealed variations in crystal quality at different growth temperatures. All samples displayed monoclinic crystal structure with the same molarity at different temperatures including 140${}^{\circ }$C, 160${}^{\circ }$C, and 180${}^{\circ }$C. Various parameters were optimized to grow nanowires and nanorods with a monoclinic crystal structure. The planes of the grown nanostructures were same across all the samples. The grown nanostructures were applied in the degradation of a crystal violet (CV) dye that is also used in optical applications. The study involved demonstrating the excellent photodegradation properties of CV by using a synthesized nanophotocatalyst and providing a detailed discussion on the effects of morphology and crystal structure with respect to photocatalytic properties. The findings also revealed the improved photocatalytic results with respect to nanostructures due to the presence of a broad light harvesting region and the lifetime of the photogenerated electron–hole pair.

The TiO₂ thin film was grown on a $64^{\circ }$ Y-axis cut, X-axis propagation lithium niobate substrate by radio frequency magnetron sputtering to fabricate a surface acoustic wave device. The sputtering ratios of argon to oxygen at 20% and post-annealing temperature at $500^{\circ }$C for 3 h were controlled to improve the photocatalytic activity of TiO₂ thin film. The effects of work frequency and input voltage of the surface acoustic wave device on the methylene blue photocatalytic degradation efficiency of the TiO₂ thin film were investigated. The TiO₂ thin film was vibrated at radio frequency by surface acoustic wave device to increase the scattering and reactive frequency for methylene blue in liquid. The surface acoustic wave device operated at 28.65 MHz work frequency and 0.95 V input voltage revealed the highest photocatalytic degradation efficiency of methylene blue. Compared to the TiO₂ thin film combined with and without surface acoustic wave device, the surface acoustic wave device enhanced the TiO₂ thin film photocatalytic degradation efficiency to 46%.

Poly(vinylidene fluoride) (PVDF, –(CH₂–CF₂)_n–) shows the effective H⁺ desorption induced by the irradiation of photon corresponding to the transition from carbon (C) 1s to σ(C–H)*. In order to clarify the effect of the C–H bond scission by the irradiation, near-edge X-ray absorption fine structure (NEXAFS) spectra and the kinetic energy (E_k) distribution of desorbed ion were observed. By the irradiation of photon near C 1s region, a new peak appears in the C 1s NEXAFS spectra at photon energy of 285 eV, which is about 3 eV lower than that of the lowest peak in the NEXAFS spectrum of the pristine PVDF film. The appearance of the lowest NEXAFS peak of irradiated PVDF film is assigned to the transition to π*. It indicates that the irradiation of photons near C 1s region introduces carbon–carbon double bonds into the backbone chain of PVDF. At early stage of X-ray exposure the yield of desorbed ion with low E_k (~ 2 eV) decreases rapidly. The ion with low E_k is assigned to H⁺ desorbed from the sp³-hybrid state, which is characteristics of the pristine PVDF. It indicates that formation of double bonds in PVDF backbone chain makes the number of sp³-hybrid state decrease. This variation occurs by irradiation of photons corresponding to the transition from C 1s to σ(C–H)* more rapidly than that to the transition to σ(C–F)*.

In recent years, there has been growing interest in the preparation of TiO₂-deposited materials for the application in different fields of photocatalytic activities, such as photocatalysis, dye-sensitized solar cells, antireflective coatings, and electro-chromic devices. TiO₂ particles were deposited on the PE surface by spraying method at room temperature. The deposition analysis was conducted by atomic force microscopy (AFM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM) for monitoring the variation in morphology and different properties. It was found that the surface was deposited uniformly with higher concentration of particles and did not affect the inherent properties of polymers. The deposited TiO₂ particles favor the photodegradation of synthetic nonbiodegradable polymeric materials, which will ultimately decompose in the environment.

Novel cross Bi₂ WO₆ microwafers have been fabricated by a facile acetone-assisted solvothermal method in high quantity. The structure characterizations of the microwafers were investigated in detail by means of X-ray powder diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the orthorhombic phase of Bi₂ WO₆ with high crystallinity can be obtained and each microwafer is polycrystalline in nature and organized by the nanoflake subunits. UV-visible diffuse reflectance spectrum of the prepared Bi₂ WO₆ microwafers demonstrates that they have absorption in the visible light region. The photocatalytic activity of cross Bi₂ WO₆ microwafers toward (Rhodamine B) RhB degradation under visible light was investigated, and it was found to be significantly better than that of Bi₂ WO₆ sample prepared by solid-state reaction (SSR-Bi₂ WO₆).

In order to enhance the photodegradation of organic pollutants, Boron-doped tin dioxide (B-doped SnO₂) composite films with narrowed band gap were successfully prepared by the sol–gel method. The samples are characterized by UV–Vis absorption spectroscopy, photoluminescence (PL), X-ray diffraction (XRD), high-resolution field emission scanning electron microscope (FE-SEM), X-ray energy dispersive spectroscopy (EDS), and Brunauer–Emmett–Teller (BET). UV–Vis absorption spectroscopy results revealed that the absorption of the B-doped SnO₂ film was clearly broadened to the visible light area. PL results showed that the recombination rate of the photo-generated species was effectively prohibited by B doping. The photocatalytic properties of the films were evaluated by degradation of organic pollutants including acid naphthol red (ANR) dye and formaldehyde solutions. Experimental results indicated that the B-doped SnO₂ film exhibited an excellent photocatalytic activity under visible light irradiation due to its strong visible light response and diminished electron–hole recombination.

In this paper, titanium dioxide methylene blue molecularly imprinted polymer (TiO₂-MB-MIP) was prepared by using MB-MIP as supported carrier. Through the study of its adsorption performance and photodegradability, it was found that the prepared TiO₂-MB-MIP has both the adsorption capacity and the photodegradation capacity on MB. The static adsorption experiment shows that its adsorption and photodegradation capacity can reach 1202.1mg⋅g${}^{-1}$ when the original concentration of MB is 5.0mg⋅mL${}^{-1}$. In addition, the degradation ability of the material in MB aqueous solutions was studied under varying light conditions. By analyzing the nitrogen and carbon content in the adsorbed solutions, the degradation process was found that the carbon and heteroatoms nitrogen in MB can be degraded to CO₂, and NH${}_4^{+}$ or NO${}_3^{-}$, respectively. The adsorption isotherm thermodynamics and kinetics model study found that the adsorption process conforms to the Langmuir isotherm equation and the quasi-secondary kinetic model, indicating that the adsorption is basically monolayer adsorption and the adsorption process is the chemical rate control step. The TiO₂-MB-MIP can be used to protect our environment by treating pigment wastewater efficiently.

The advantage of doping of TiO₂ with copper has been utilized for enhanced degradation of pesticide under visible light irradiation. The sol–gel method has been undertaken for the synthesis of copper-doped TiO₂ by varying the dopant loadings from 0.25 wt.% to 1.0 wt.% of Cu²⁺. The doped samples were characterized by UV-Visible Diffuse Reflectance Spectroscopy (DRS), N₂ adsorption–desorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometry (EDS). The photocatalytic activity of the catalyst was tested by degradation of dichlorvos under visible light illumination. The results found that 0.75 wt.% of Cu²⁺ doped nanocatalysts have better photo catalytic activity than the rest of percentages doped, undoped TiO₂ and Degussa P25. The reduction of band gap was estimated and the influence of the process parameters on photo catalytic activity of the catalyst has been explained.

This work presents an important analysis and comparative study between two organic waste rhodamine B (RhB) and methyl orange (MO) dyes as pollutant models degeneration under sunlight. Hematite ($\alpha$-Fe₂O₃) nanorods were synthesized and deposited on glass substrates using an efficient and simple one-step hydrothermal method. The nanorods were characterized by XRD, FESEM, EDX, and UV–Vis equipment. The photodegeneration parameters of $\alpha$-Fe₂O₃ films were calculated by modeling the photodegradation of MO and RhB dyes as pollutants under sunlight irradiation for 150min. Results revealed that the degradation efficiency of $\alpha$-Fe₂O₃ films of MO and RhB dyes was 72.7% and 91.9%, respectively. The optimized photocatalyst degraded RhB more efficiently than the MO solution.

In this research, nickel oxide (NiO) peculiar nanosheets with a thickness of less than 50 nm were produced via a low-cost, one-step, safe hydrothermal process. The reaction was conducted with two concentrations of Ni (NO${}_3{)}_2\cdot$6H₂O (0.01 and 0.03) at 120${}^{\circ }$C for 3 h. Methylene Blue (MB) dye was used to examine the photoactivity of NiO nanosheet films under sunlight. The prepared NiO nanosheet films were evaluated using XRD, FE-SEM, EDX and UV-visible techniques. Accordingly, (FE-SEM) images confirm that the films synthesized by a hydrothermal method were flower-like nanosheets with a diameter of 33.4–52.7 nm, and the thickness of the NiO film is about 3.629 $\mu$m. The average particle size and crystalline structures were estimated using XRD Analysis. However, both films were then exposed to direct sunshine for 80 min. The respective photocatalytic efficiencies of films were calculated to be 85% and 88%. The effectiveness of the photocatalytic degradation for eliminating Methylene Blue (MB) depends on the concentration, proving that the efficiency can be improved by increasing the concentration.

In this study, the photocatalytic degradation of RhB dye in an aqueous solution using ZnO nanoparticles (NPs), $\gamma$-Fe₂O₃, $\gamma$-Fe₂O₃–ZnO, Ag–ZnO, and $\gamma$-Fe₂O₃–Ag–ZnO nanomaterials generated using poinciana leaf extract is presented. The nanomaterials were prepared utilizing environmentally friendly methods and poinciana leaf extract. The properties of the originally generated nanomaterials, analyzed through techniques such as atomic force microscopy (AFM), UV–visible spectroscopy, X-ray, electron microscopy, and FE-SEM, have been described. The hexagonal structure of ZnO wurtzite was also discovered to align with the XRD findings. Additionally, EDX mapping was employed to analyze the composition of the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite. A topological investigation confirmed the roughness of the created nanostructures. Regarding the photocatalytic Rhodamine B (RhB) dye degradation studies, the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite demonstrated superior performance compared to pure ZnO in breaking down dye molecules under visible light exposure. Employing an ideal configuration of 1.0 g/L of photocatalyst, pH 10, and 10 ppm of RhB, an impressive photodegradation effectiveness of nearly 99% was achieved in just 45 min of light exposure. An analysis of reactive species was conducted to determine the photodegradation efficiency of $\gamma$-Fe₂O₃–Ag–ZnO. To investigate the impact of the microorganisms Escherichia coli and Staphylococcus aureus on the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite, the results indicated that the $\gamma$-Fe₂O₃–Ag–ZnO nanocomposite achieved a high rate of success in neutralizing and eradicating these bacteria.

Photochemical and photophysical measurements were conducted on pentoxy and naphthaloxy appended zinc and magnesium phthalocyanines. We describe in this paper the synthesis as well as unexpected photodegradation behavior of naphthaloxy appended magnesium phthalocyanines. General trends are described for quantum yields of photodegradation, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds.

An anion-resin carrying the catalyst iron(II) tetra(1,4-dithin)porphyrazine, (Fe(II)Pz(dtn)₄/resin), may effectively interact with the lone-pair electron of the sulfur in the Fe(II)Pz(dtn)₄ to keep the absorption for the catalyst molecule, which can efficiently activate molecular oxygen coordinated with iron(II) on the axial orientation of Fe(II)Pz(dtn)₄ through electron transfer in a heterogeneous process. On the other hand, the hydrophilic property of the resin also facilitates adsorption of the anion-substrates in the aqueous solution onto the unoccupied resin surface to increase the substrate concentration around the Fe(II)Pz(dtn)₄ and the contact probability between the substrate with activated molecular oxygen to promote the oxidative degradation of these adsorbed substrates. The stability and repeatability of the Fe(II)Pz(dtn)₄/resin were determined by some control experiments. The results indicate that Fe(II)Pz(dtn)₄ was stable enough in the presence of active oxygen species under irradiation of visible light and could degrade recalcitrant organic pollutants such as rhodamine B and p-nitrobenzoic acid. It can be reused at least 5 cycling runs without losing activity.

The first observation of direct room temperature delayed fluorescence from non-peripherally substituted phthalocyanines is reported. The quantum yields of delayed fluorescence and delayed fluorescence lifetimes were determined and are discussed. The normal fluorescence quantum yields and photodegradative quantum yields of these compounds were also determined.

Two new zinc phthalocyanine derivatives bearing four 3,5-di-tert-butyl-4-hydroxyphenyl (ZnPc1) and 3,5-dimethylphenoxy (ZnPc2) have been synthesized and proved by elemental analyses and UV-vis, ¹H NMR, FTIR and MALDI-TOF mass spectra as spectroscopic determination. Thermal stabilities of these neutral Zn-phthalocyanines were performed by thermal gravimetric analysis and, significantly, were found stable up to 373 °C for ZnPc1 and 550 °C for ZnPc2. In addition, the photostability of the sensitizers was quite successful within 240 min. Furthermore, photodynamic therapy has been investigated using these neutral phthalocyanines. Singlet oxygen generation capacities of ZnPc1 and ZnPc2 were studied using 1,3-diphenyl-iso-benzofuran (50.0 μM) as a selective singlet oxygen trap in DMSO and both of them demonstrated very high singlet oxygen generation capacity. Photodynamic therapy is of considerable interest for its potential as an antimicrobial therapy on the grounds that the photodynamic activity of these compounds was tested against a Gram-negative bacteria, Escherichia coli and a Gram-positive bacteria, Staphylococcus aureus. Suspensions of the microorganisms were irradiated for 240 min in the presence of ZnPc1 (with hydrophilic group) and ZnPc2 phthalocyanines. In order to simulate solar radiation, we used a 750 W xenon lamp. Minimum photosensitizer concentration was used as 0.1 mg.10 mL^-1 in 1% dimethylsulfoxide/phosphate buffer saline solution (DMSO/PBS). Moreover, the photostability of these compounds has been investigated and the effect of the amount of DMSO tested against selected bacteria. In the dark, with and without Pcs, bacterial inactivation did not occur. Bacterial inactivation by light with ZnPc1 was observed in response to Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus, whereas the photoinactivation studies with ZnPc2 have revealed that the lack of its activity is due to its poor affinity for either of the organisms. These results suggest that a neutral amphiphilic photosensitizer may be easily used in an application concerning photoinactivation of bacterial cells as well as ionic photosensitizers.

TiO₂/PS, Fe(III) tetraphenylporphyrin (FeTPP)/PS and TiO₂/FeTPP/PS nanofibers were prepared by electrospinning a mixture solution of corresponding compounds in N, N-dimethylformamide (DMF). The absorbance of FeTPP was characterized by UV-vis spectroscopy. The surface morphologies of these electrospun mats were evaluated with scanning electron microscope (SEM). Their photocatalytic activities were examined with the photodegradation reaction of methyl orange in aqueous solution under the irradiation of visible light. The result shows that the photocatalytic activity of TiO₂/FeTPP/PS mat is higher than that of FeTPP/PS mats, which in turn is better than that of TiO₂/PS mats in the photodegradation of methyl orange. The degradation percent of methyl orange could be up to 97.8% in 3 h by the FeTPP/TiO₂/PS mat photocatalyst.

Although tungsten porphyrins are known as mimicking models in biology, only a few papers about its chemical properties have been reported, the rarity of studies being attributed to the difficulties encountered in their synthesis due to their low stability. In this paper 5,10,15,20-tetra-p-phenyl-porphyrin tungsten(VI) chlorine (TPPWCl₄) was studied, this metallo-porphyrin characterized by different analytical techniques: UV-vis, FTIR, ESR, mass spectrometry, including photophysical determination of its singlet oxygen quantum yield, too. Its photodegradation reaction with the mechanism and species involved into this destruction reaction processes is discussed, too. Also, in order to maintain its photostability, TPPWCl₄ has been incorporated into solid substrates, such as ZnO and TiO₂, and these composites were subsequently tested in the photooxidation reaction of isoamylenes (2-methyl-2-butene and 2-methyl-1-butene mixture).

The novel 2,3,9,10,16,17,23,24-tetra-(15-crown-5)phthalocyaninato indium(III) hydroxide [(15C5)₄Pc]In(OH)(I) was obtained by direct interaction of tetra-(15-crown-5)-phthalocyanine with indium acetylacetonate with 90% yield. The set of UV-vis, ¹H NMR and MALDI-TOF spectroscopy data allowed the unambiguous interpretation of complex structure. It was shown that the developed synthetic approach can be also used for synthesis of indium(III) 2,3,9,10,16,17,23,24-octabutoxyphthalocyanine [(BuO)₈Pc]In(OH)(II). Photophysical characteristics (fluorescence and singlet oxygen quantum yields) of I were established. The photochemical stability of I was compared with tetra-(15-crown-5)-phthalocyanine H₂[(15C5)₄Pc] and aluminum(III) complex [(15C5)₄Pc]Al(OH). It was found that cation-induced formation of cofacial dimers [2I × 4MX] (M = K⁺, Rb⁺, X = CO₃^2-, OPic^-, OPiv^-, SO₄^2-, ClO₄^-, Br^-) resulted in significant enhancement of complex photostability.