The design of novel visible light driven Ag/CdO as smart nanocomposite for photodegradation of different dye contaminants

Hydrothermal Synthesis of Fe-Doped Cadmium Oxide Showed Bactericidal Behavior and Highly Efficient Visible Light Photocatalysis

Cationic dyes present in industrial effluents significantly reduce the effectiveness of remediation operations. Considering the terrible impact of these pollutants on environment and biodiversity, investigating strategies to remove potentially harmful compounds from water is becoming an increasingly intriguing issue. In this work, we employed a simple hydrothermal technique to synthesize Fe-doped CdO (2, 4, and 6 wt %) nanostructures and assessed their efficacy in degrading methylene blue (MB) dye and inhibiting the growth of Staphylococcus aureus and Escherichia coli, respectively. Structural, morphological, and optical characterization of produced nanomaterials was also performed using X-ray diffraction, TEM, and UV absorption spectra. The photocatalytic decomposition of MB was significantly enhanced (58.8%) by using Fe (6 wt %)-doped CdO catalysts for 80 min under irradiation. In addition, 2.05-5.05 mm inhibitory zones were seen against Gram-positive bacteria (S. aureus), whereas the range for Gram-negative bacteria (E. coli) was 1.65-2.75 mm. These nanostructures were shown to be very effective inhibitors of beta-lactamase, d-alanine-d-alanine ligase B, and fatty acid synthase inhibitor by in silico molecular docking investigations.

The MIL100(Fe)/BaTi0.85Zr0.15O3 nanocomposite with the photocatalytic capability for study of tetracycline photodegradation kinetics

The visible light-active nanocomposite with the photocatalytic capability was facile one-pot solvothermal method successfully synthesized. X-ray diffraction (XRD), Thermogravimetry and Derivative Thermogravimetry (TG-DTG), Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (SEM-EDX), Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Fourier Transform Infra-Red (FT-IR) analysis were employed to characterize the synthetized BaTi_0.85Zr_0.15O3, MIL-100(Fe), and the MIL-100(Fe)/BaTi_0.85Zr_0.15O₃ samples. As a result of the Scherrer equations, the size of grains for MIL-100(Fe), BaTi_0.85Zr_0.15O₃, and MIL-100(Fe)/BaTi_0.85Zr_0.15O₃ was estimated to be 40.81, 12.00, and 22.70 nm, respectively. MIL-100(Fe), BaTi_0.85Zr_0.15O₃, and MIL-100(Fe)/BaTi_0.85Zr_0.15O₃ samples showed bandgap values of 1.77, 3.02, and 2.56 determined from their absorption edge wavelengths. In the photodegraded solutions, chemical oxygen demand (COD) data and tetracycline (TC) absorbencies were used to obtain the rate constants of 0.032 min^-1 and 0.030 min^-1, respectively. This corresponds to t_1/2-values of 27.7 min and 21.7 min, respectively, for the degradation and mineralization of TC molecules during photodegradation process.

Noble metal nanoparticles (Mx = Ag, Au, Pd) decorated graphitic carbon nitride nanosheets for ultrafast catalytic reduction of anthropogenic pollutant, 4-nitrophenol

We report an effective facile immobilization of noble nanoparticles (M_x = Ag, Au and Pd) assembled on g-C₃N₄ (g-CN) prepared via a simple ultra-sonication strategy. The M_x assembled g-CN nanocomposites were applied for the effective conversion of 4-nitrophenol (4-NP). As prepared nanocomposites were characterized by techniques of XRD, SEM-EDS, TEM, XPS, and FT-IR analysis to gain crystallographic structural, and morphological insights. The Pd@g-C₃N₄ (Pd@g-CN) nanocomposite exhibited best catalytic performance (k_app = 1.141 min^-1) toward the conversion of 4-NP to 4-aminophenol (4-AP), almost 100% within 4 min using aqueous sodium borohydride (NaBH₄). The higher catalytic efficiency of Pd@g-CN could be attributed to the surface electron density on the Pd and rapid electron transfer capacity. Interestingly, g-CN not only role as a stabilizer but also provided compatibility for noble metal deposition, which improves the chemical and morphological stability of noble metal nanoparticles. Different reaction parameters including concentrations of 4-NP, and catalyst amount were studied. These unique combinations make noble metal nanoparticles anchored g-CN nanosheets an ideal platform for catalysis applications and environmental remediation.

Synthesis of Ti4+ doped Ca-BiFO3 for the enhanced photodegradation of moxifloxacin

In recent years, the continuously increasing demand for wastewater treatment has increased research on perovskite-based materials with narrow band gaps.

Synthesis and Properties of p-Si/n-Cd1−xAgxO Heterostructure for Transparent Photodiode Devices

We developed silver-doped Cd1–xAgxO thin films (where x = 0, 0.01, 0.02, 0.03 and 0.04) on amorphous glass substrate by an automated nebulizer spray pyrolysis set-up. The XRD patterns show rock salt cubic crystal structures, and the crystallite sizes vary with respect to Ag doping concentrations. SEM images exhibited a uniform distribution of grains with the addition of Ag; this feature could support the enhancement of electron mobility. The transmittance spectra reveal that all films show high transmittance in the visible region with the observed bandgap of about 2.40 eV. The room temperature photoluminescence (PL) studies show the increase of near-band-edge (NBE) emission of the films prepared by different Ag doping levels, resulting in respective decreases in the bandgaps. The photodiode performance was analyzed for the fabricated p-Si/n-Cd1–xAgxO devices. The responsivity, external quantum efficiency and detectivity of the prepared p-Si/n-Cd1–xAgxO device were investigated. The repeatability of the optimum (3 at.% Ag) photodiode was also studied. The present investigation suggests that Cd1–xAgxO thin films are the potential candidates for various industrial and photodetector applications.

Adsorption of Anionic Dyes Using a Poly(styrene-block-4-vinylpyridine) Block Copolymer Organogel

An organogel was prepared by chemically cross-linking a poly(styrene-block-4-vinylpyridine) diblock copolymer using dibromododecane in dimethylformamide. Analysis of the prominent structure peak in small-angle X-ray scattering along with the results of light scattering and rheological profile suggests the bridging of the spherical micelles to one another to form an interconnected network after gelation. The use of this organogel as a selective adsorbent for removing anionic dyes from individual aqueous dye solutions and in a mixture of cationic and anionic dye solutions has shown more than 90% removal of the anionic dyes within 2 h. The regeneration and reusability studies showed that even after 20 cycles, the adsorption property of the organogel holds extremely well still beyond 90%. These results are indicative of the potential use of poly(styrene-block-4-vinylpyridine) organogel for the anionic ions removal in wastewater treatment.

Chemically synthesized Sb2S3 hollow-spheres for significantly fast and reliable visible light driven dye photodegradation

Sb₂S₃ hollow-spheres in powder form were synthesized through a facile chemical route. The synthesized material was found to have notably high specific surface area. After annealing it showed broadband absorption of light within the visible region. The valance band and conduction band of the synthesized semiconductor were also positioned appropriately (w.r.t NHE) so that the required redox reactions with water in presence of the photogenerated excitons are facilitated. These factors make it a suitable candidate for photocatalytic applications towards the degradation of dye based water pollutants. The synthesized material was established through systematic structural, compositional and optical characterizations. The photocatalytic efficacy toward the degradation of cationic, anionic and neutral dyes has been studied and the best degradation efficiency of 99.72% within 20 min has been achieved at a rate of 0.2920/min, which is significantly higher than many previous reports. Reusability, one of the major factors for the practical application of a catalyst, has also been studied in detail by investigating the probable changes in structural properties as well as in performance after several cycles of photodegradation. The reliability studies yielded encouraging results even after 50th cycle of photodegradation. The effect of catalyst loading on the photodegradation efficacy has also been studied.

Influence of Carrier Gas Pressure on the Physical Properties of CdO Thin Films

Conducting cadmium oxide (CdO) thin film samples were deposited on amorphous glass substrates at the optimized substrate temperature (200 °C) as a function of carrier gas pressure (10.8, 12.7, 14.7, 16.7 and 18.6 × 104 N m−2 respectively) by spray pyrolysis technique using nebulizer. XRD results showed that all the CdO thin films were polycrystalline in nature along with cubic structure. The scanning electron microscopy (SEM) images revealed that all the thin films had a sphere like grains without any cracks. The elemental composition of the film is analyzed with EDAX spectrum formed in stochiometric range. Direct energy gap values were found to be had decreased from 2.46 to 2.42 eV as the function of carrier gas pressure had increased from 10.8 to 14.7 × 104 (N m−2) and the energy gap increased further. All the as deposited samples of Cd–O vibration bond (690 cm−1) were confirmed by FTIR spectrum. PL emission spectra revealed that all the CdO thin films exhibit a strong emission (green) peak at 520 nm. High carrier concentration (2.88 × 1019 cm−3), low resistivity (4.76 × 10−3 Ω cm) and high figure of merit (25.0 × 10−3) were observed for 14.7 × 104 (N m−2) carrier gas pressure of CdO thin film.

A comprehensive study on the photocatalytic activity of coupled copper oxide-cadmium sulfide nanoparticles

Coupled CdS-CuO nanoparticles (NPs) subjected in the photocatalytic degradation of Methylene blue (MB) aqueous solution. The calcination temperature and the crystallite phase of CuO had a significant role on the photocatalytic activity of the coupled system and CuO_200/2h-CdS catalyst (containing CuO calcined at 200°C for 2h) showed the best photocatalytic activity. The coupled system showed increased activity with respect to the monocomponent semiconductors. The prepared catalysts characterized by x-ray diffraction (XRD), scanning electron microscope equipped with energy dispersive X-ray (EDX) analyzer, x-ray mapping, Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS) techniques. The best degradation extent of MB was obtained at: C_MB: 1mgL^-1, pH5, 80min irradiation time and 0.8gL^-1 of the CuO_200/2h-CdS catalyst. The chemical oxygen demand (COD) confirmed about 83% of MB molecules can be mineralized at the optimum conditions.