Photocatalytic activities of AgBr/Y-zeolite in water under visible light irradiation

BiVO4/WO3 nano-composite: characterization and designing the experiments in photodegradation of sulfasalazine

A BiVO₄-WO₃ nano-composite (NC) was hydrothermally prepared and characterized by different techniques including X-ray diffraction (XRD), scanning electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer, X-ray mapping, UV-Vis reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The average crystallite size of 8.5 nm was estimated for the composite by the Williamson-Hall equation. The band gap energies of 2.46, 3.02, and 2.95 eV were obtained for the direct electronic transitions of BiVO₄, WO₃, and the composite, respectively. The point of zero charges (pHpzc) of the composite was also estimated at 5. The composite was then used in the photodegradation of sulfasalazine (SSZ). When the moles of WO₃ was four times greater than BiVO₄, the best photocatalytic activity and the lowest PL intensity were obtained. The simultaneous effects of the experimental variables on the boosted photocatalytic activity of the composite (to the single semiconductors) were studied by the response surface methodology (RSM). A significant quadratic model was confirmed for processing the data based on the F value of a model F value of 63.55 > F_{0.05, 14, 13} = 2.55. This was also confirmed by LOF F value of 2.56 < F_{0.05, 10, 3} = 8.79. Besides, the multiple correlation coefficients R² (R² = 0.9856), adjusted R² (adj-R² = 0.9701), and predicted R² (pred-R² = 0.9098) confirm the goodness of the model. The optimal run included C_SSZ 9 mg/L, pH 4, 40 min irradiation time, and 0.8 g/L of the composite under the visible light irradiation.

A label-free aptamer-based cytosensor for specific cervical cancer HeLa cell recognition through a g-C3N4-AgI/ITO photoelectrode

Facile and efficient detection of cancer cells in the early phases of the disease is one of the main challenges in cancer diagnostics. It has been found that photoactive materials and bio-recognition elements are two key factors in the development of promising photoelectrochemical (PEC) biosensors for cancer cell detection, which can play significant roles for realizing early cancer diagnostics with high sensitivity and selectivity. In this study, we designed a novel label-free PEC aptamer-based cytosensor for the specific detection of cancer cells such as HeLa cells by using water-dispersible g-C₃N₄-AgI nanocomposites as visible light-sensitive materials and anti-CEM/PTK7 aptamer as the bio-recognition element. It was observed that when a suitable amount of AgI nanoparticles was doped in two-dimensional graphite-like carbon nitride nano-sheets (g-C₃N₄ NSs), the visible light photocurrent response could be significantly improved. The PEC response of the as-prepared biosensor based on the g-C₃N₄-AgI/ITO photoelectrode was linearly proportional to the relevant cancer cells such as HeLa cells at concentrations ranging from 10 to 10⁶ cells per mL with a limit of detection of 5 cells per mL. In addition, the g-C₃N₄-AgI/ITO photoelectrode and the fabricated cytosensor exhibited long-term stability, good reproducibility, excellent selectivity, and high sensitivity, demonstrating the successful conjugation of g-C₃N₄-AgI NSs with the aptamer and target cancer cells in the high performance PEC cytosensor.

In situ growth of Ag/Ag2O nanoparticles on g-C3N4 by a natural carbon nanodot-assisted green method for synergistic photocatalytic activity

Novel visible-light-driven Ag/Ag₂O@g-C₃N₄ hybrid materials were synthesized successfully via a green, facile hydrothermal treatment approach by reducing AgNO₃ with carbon nanodots for the first time.

Cubic Ag/AgBr–graphene oxide nanocomposite: sono-synthesis and use as a solar photocatalyst for the degradation of DCF as a pharmaceutical pollutant

In this study, novel Ag/AgBr/graphene oxide (GO) nanosheets were successfully preparedviaa facile and fast sonochemical route for the first time, and ultrasound has a key role in the preparation process.

Highly efficient and recyclable nanocomplexed photocatalysts of AgBr/N-doped and amine-functionalized reduced graphene oxide

Although silver bromide has recently drawn considerable attention because of its high photocatalytic activity, it tends to form agglomerated metallic silver under the irradiation of visible light. Therefore, photocatalytic activity decreases with time and cannot be applied for repeated uses. To overcome this limitation, in the present work, we complexed AgBr with nitrogen doped (N-doped) and amine functionalized reduced graphene oxide (GN). N-doped and/or amine functionalized graphene shows intrinsically good catalytic activity. Besides, amine groups can undergo complexation with silver ions to suppress its reduction to metallic Ag. As a result, these complexed catalysts show excellent photocatalytic activity for the degradation of methylene blue (MB) dye under the irradiation of visible light. Photocatalytic degradation of MB shows that the catalytic activity is optimized at a condition of 0.5 wt % GN, under which ∼99% of MB was degraded only after 50 min of visible light irradiation. Notably, the complexed catalyst is quite stable and retained almost all of its catalytic activity even after greater than 10 repeated cycles. Moreover, the catalyst can also efficiently decompose 2-chlorophenol, a colorless organic contaminant, under visible light exposure. Detailed experimental investigation reveals that hydroxyl (·OH) radicals play an important role for dye degradation reactions. A relevant mechanism for dye degradation has also been proposed.

As-synthesis of nanostructure AgCl/Ag/MCM-41 composite

In this work, we present the simple synthetic route for silver chloride/silver nanoparticles (AgCl/Ag-NPs) using as-synthesis method. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed that when AgNO(3) content is below 0.1 wt.% in synthetic gel, the guest AgCl/Ag-NPs is formed on the silica channel wall, and lower exists in the crystalline state. When AgNO(3) content exceeds this value, AgCl/Ag nanoparticles can be observed in high crystalline state. The absorption at 327 nm ascribed to the characteristic absorption of the AgCl semiconductor. Ag nanoparticles have been shown to exist in the nanocomposite at 375 nm. When AgNO(3) content is above 0.1 wt.% in synthetic gel, spectra exhibited stronger absorption at 450-700 nm that was attributed to the surface plasmonic resonance of silver nanoparticles. The obtained AgCl/Ag/MCM-41 sample exhibit enhanced photocatalytic activity for the degradation of methylene blue under visible-light irradiation.

Nanostructured AgBr loaded TiO2: An efficient sunlight active photocatalyst for degradation of Reactive Red 120

The AgBr loaded TiO₂ catalyst was prepared by a feasible approach with AgBr and tetraisopropyl orthotitanate and characterized by BET surface area measurement, diffuse reflectance spectra (DRS), scanning electron microscope (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscope (AFM) analysis. The results of characterization reveal that AgBr loaded TiO₂ has a nanostructure. Formation of the nanostructure in AgBr loaded TiO₂ results in substantial shifting of the absorption edge of TiO₂ to red and enhancement of visible light absorption. Electrochemical impedance spectroscopy measurements reveal that AgBr loaded TiO₂ has a higher photoconductivity than prepared TiO₂ due to higher separation efficiency of electron-hole pairs. Cyclic voltammetric studies reveal enhanced conductivity in AgBr loaded TiO₂, which causes an increase in its photocatalytic activity. AgBr loaded TiO₂ exhibited a higher photocatalytic activity than TiO₂-P25 and prepared TiO₂ in the photodegradation of Reactive Red 120 (RR 120).

Photocatalytic activity of novel AgBr/WO3 composite photocatalyst under visible light irradiation for methyl orange degradation

A novel AgBr/WO(3) composite photocatalyst was synthesized by loading AgBr on WO(3) substrate via deposition-precipitation method and characterized by XRD, SEM and DRS. The as-prepared AgBr/WO(3) was composed of monoclinic WO(3) substrate and face-centered cubic AgBr nanoparticles with crystalline sizes less than 56.8 nm. AgBr/WO(3) had absorption edge at about 470 nm in the visible light region. The optical AgBr content in AgBr/WO(3) was 0.30:1 (Ag/W) at the corresponding apparent rate, k(app), of 0.0160 min(-1) for MO degradation. The highest k(app) was 0.0216 min(-1) for 4 g/L catalyst. The OH acted as active species. Addition of H(2)O(2) within 0.020 mmol/L can efficiently trap electrons to generate more OH and further improved photocatalytic activity of AgBr/WO(3).

Photocatalytic Mechanism of Action of Apatite-Coated Ag/Agbr/Tio2 on Phenol and Escherichia Coli and Bacillus Subtilis Bacteria Under Various Conditions

Multi-component photocatalysts based on apatite-coated Ag/AgBr/TiO2 were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-stal ic. The median ism for deactivation of bacteria in the dark can be related to the linkage between the phosphate group of the composite and the outer membrane of the cell. The photocatalytic destruction of bacteria under visible I ight indicates that attachment of the catalysts to the outer wall of the cell causes them to destroy effectively the cell wall and inner membrane by various reactive species such as OH, O2 - and 1O2. Thus this effect increases the photoactivity more than two-fold. Oxidation of phenol was also achieved under visible light- and UVA- irradiation using apatite-coated Ag/AgBr/TiO2 powders. Under UVA illumination, the ‘OH produced from the hole of the TiO2 valence band is responsible for the photodegradation of phenol, while under visible light, AgBr acts as the photoactive component of the catalyst, that can not produce’ OH and oxidize the phenol.

AgBr/nanoAlMCM-41 visible light photocatalyst for degradation of methylene blue dye

A novel photocatalytic material was synthesized by dispersion of AgBr in nanoAlMCM-41 material. The AgBr/nanoAlMCM-41 sample shows strong absorption in the visible region because of the plasmon resonance of Ag nanoparticles in AgBr/nanoAlMCM-41. The catalysts were characterized using XRD (X-ray diffraction), UV-visible diffused reflectance spectra (UV-vis DRS) and scanning electron microscopy (SEM). The photocatalytic activity and stability of the synthesized catalysts were evaluated for methylene blue (MB) degradation in aqueous solution in the presence of 200 W tungsten filament Philips lamp. Several parameters were examined, catalyst amount, pH and initial concentration of MB, AgBr loading. The effect of dosage of photocatalyst was studied in the range 0.05-1.00 g/L. It was seen that 0.1 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The support size was obtained about 9-100 nm. In the same way, the average size of AgBr nanoparticles was about 10nm before visible radiation. After visible radiation the average size of AgBr nanoparticles was about 25 nm.