Combustion synthesis of calcium doped ZnO nanoparticles for the photocatalytic degradation of methylene blue dye

ZnO nanoparticles are one of the prominent photocatalysts for environmental applications due to its high redox ability, nontoxic and higher stability. This report explains the synthesis of ZnO nanoparticles by a simple solution combustion method using zinc nitrate hexahydrate as an oxidizing agent and incense stick powder as fuel at 400 °C. Several techniques were adopted for the characterization of the obtained product. X-ray diffraction (XRD) pattern shows that a lower concentration of fuel gives pure ZnO and a higher concentration of fuel results in calcium doped ZnO with a cubic phase having a crystallite size of 32–28 nm. UV–vis spectrum shows that as the fuel concentration increases, band gap decreases and reaches to 3.33 eV for 3 g of fuel. Spongy networks with many pores wereobserved in the scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed the average particle size of Ca doped ZnO NPs is about 20 nm. Pure and Ca doped ZnO nanoparticles were examined for photocatalytic degradation of methylene blue (MB) dye under UV light irradiation. The results prove that Ca doped ZnO nanoparticles show good photocatalytic activity.     

Facile fabrication of ZnO/N‐doped helical carbon nanotubes composites with enhanced photocatalytic activity toward organic pollutant degradation

Novel ZnO/N‐doped helical carbon nanotubes (ZnO/N‐HCNTs) composites were successfully synthesized via a facile chemical precipitation approach at room temperature. The sample was well characterized by X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity was evaluated in the degradation of methylene blue (MB) aqueous solution under UV light irradiation. It is found that ZnO nanoparticles were highly and uniformly anchored on the surface and inner tubes of the N‐HCNTs with size of about 5 nm, and significantly enhanced the photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity of ZnO/N‐HCNTs composites can be ascribed to the integrative synergistic effect of effective interfacial hybridization between N‐HCNTs and ZnO nanoparticles and the prolonged lifetime of photogenerated electron–hole pairs. Moreover, the ZnO/N‐HCNTs could be easily recycled without any obvious decrease in photocatalytic activity and could be promote their application in the area of environmental remediation.     

Green synthesis,characterization, and biological activities of saffron leaf extract-mediated zinc oxide nanoparticles: A sustainable approach to reuse an agricultural waste

To increase the profitability and sustainability of agricultural waste, a facile green approach was established to synthesize zinc oxide nanoparticles (ZnO NPs) using saffron leaf extract as a reducing and stabilizing agent. Structural characteristics of NPs were investigated by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and UV–Visible (UV–Vis) spectroscopy. Characterization results revealed that ZnO NPs is highly crystalline with a hexagonal wurtzite structure and spherical particles with diameter less than 50 nm, as confirmed by XRD and FESEM techniques. UV–Vis absorption spectra depicted an absorption peak at 370 nm, which confirms the formation of ZnO NPs. FTIR spectral analysis confirmed the presence of functional groups and metal oxygen groups. The biological activities of ZnO NPs were also investigated. The antibacterial effect of ZnO NPs was investigated against selected food pathogens (Salmonella Typhimurium, Listeria monocytogenes, and Enterococcus faecalis). The study results prove that the green synthesized ZnO NPs show enhanced antibacterial activity against S. Typhimurium when compared with other strains. A dose-dependent free radical scavenging activity was observed for ZnO NPs in both 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and fluorescence recovery after photobleaching (FRAP) assays. The ZnO NPs were evaluated for their photocatalytic activity during the degradation of methylene blue (MB) dye in aqueous solutions. The maximum removal of MB achieved was 64% with an initial ZnO NP concentration of 12 mg/mL under UV light. The present study revealed that the agricultural waste (saffron leaf) provides a simple and eco-friendly option to sustainably synthesize ZnO NPs for use as a photocatalyst. In addition, this is the first report on saffron leaf-mediated synthesis of ZnO NPs.     

Surfactant assisted hydrothermal synthesis of SnO nanoparticles with enhanced photocatalytic activity

SnO nanoparticles have been successfully synthesized in the presence of Triton-X 100 (TX-100) surfactant via hydrothermal method for the first time, and the photocatalytic activity under UV and visible light irradiation for the degradation of Methylene Blue (MB) and Rhodamine B (RdB) organic textile dyes was investigated. The structural, morphological and chemical characterizations were investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), UV–vis. diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) analysis. The results reveal that the addition of surfactant, TX-100, in the precursor solutions leads to reduction in crystallite size with significant changes in morphological structure of SnO nanoparticles. The synthesized SnO nanoparticles show excellent photocatalytic activity under UV or visible light irradiation. MB and RdB dyes degraded completely under UV irradiation after 90 and 150 min, respectively. Also, MB and RdB dyes degraded only 150 min later under visible light illumination with a little amount of photocatalyst (0.8 g/L). Hence, this work explores the facile route to synthesizing efficient SnO nanoparticles for degrading organic compound under both UV and visible light irradiations.     

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

In this study, novel ternary Fe₂O₃/ZnO/ZnFe₂O₄ (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.     

Band structure tuning of ZnO/CuO composites for enhanced photocatalytic activity

The toxic dye pigments, even in small quantities, can damage ecosystems. Removing organic, inorganic, and microbiological contaminants from wastewater via heterogeneous photocatalysis is a promising method. Herein, we report the band structure tuning of ZnO/CuO nanocomposites to enhance photocatalytic activity. The nanocomposites were synthesized by a chemical approach using step-wise implantation of p-type semiconductor CuO to n-type semiconductor ZnO. Various characterization techniques such as X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and UV spectroscopy were used to investigate the crystal structure, surface morphology, elemental composition and optical properties of the synthesized samples. As the CuO content increased from 10% to 50% in ZnO/CuO nanocomposites, the optical bandgap decreased from 3.36 to 2.14 eV. The photocatalytic activity of the samples was evaluated against the degradation of methylene blue (MB) under visible irradiation. Our study demonstrates a novel p–n junction oxide photocatalyst based on wt. 10% CuO/ZnO with superior photocatalytic activity. Effectively 66.6% increase in degradation rate was achieved for wt. 10% CuO/ZnO nanocomposite compared to pure ZnO nanoparticles.     

Synthesis of the Dy: SrMoO4 with High Photocatalytic Activity under Visible Light Irradiation

Dysprosium (Dy)‐doping SrMoO₄ (with different molar ratio of Dy/Sr = 0/100, 10/100, 15/100 and 20/100) have been synthesized by high temperature thermal decomposition of metal–organic salt in organic solvent with a high boiling point. Their structures, morphology, and optical properties were characterized by X‐ray diffraction (XRD), high‐resolution tuning electron microscopy ((HR)TEM), X‐ray photo‐electron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Using this method, the pure phase, nano‐size, and low band gap of SrMoO₄ sample are obtained. The results shows that the size of as‐synthesized SrMoO₄ nanoparticles was about 200 nm. The band gap of Dy‐doped SrMoO₄ ranges from 3.76–3.90 eV, and decreases with increasing Dy concentration. The photocatalytic performance of as‐syntheszied products were determined from the degradation of methylene blue (MB) by UV–vis light irradiation. The 15 mol%Dy‐doped SrMoO₄ sample shows the best performance for photocatalytic degradation of methyl blue of nearly 100% in 120 min under visible irradiation, which is higher than most of those reported before. The present work is meaningful for revealing the underlying mechanism in photocatalyst and improving the photocatalytic performance.     

Biosynthesis of cerium oxide nanoparticles and its cytotoxicity survey against colon cancer cell line

Nanoparticles of cerium oxide (CeO₂-NPs), as a metal oxide of rare earth, have found an important role in improving technologies such as polishing, the degradation of harmful industrial dyes and even the treatment of some diseases. Therefore, the development of quick and inexpensive production methods for CeO₂-NPs is sought by researchers. In the present study, we report the biosynthesis of CeO₂-NPs using aqueous extract of Salvadora persica. Synthesized nanoparticles were investigated through powder X-ray diffraction (PXRD), ultraviolet–visible (UV–vis), Fourier transform infrared, transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray and Raman techniques. The UV–vis result shows an absorption peak at 325 nm, which confirms the formation of CeO₂-NPs. The band-gap of synthesized nanoparticles (4.1 eV) is higher than in its bulk state. PXRD and Raman show a crystalline fluorite cubic structure for synthesized nanoparticles. The morphology of synthesized nanoparticles shows a uniform and almost spherical shape via TEM and FESEM images. The particles size was estimated in the range of 10–15 nm. Cytotoxic activity of synthesized nanoparticles was determined through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against a colon (HT-29) cancer cell line. The results did not show any significant cytotoxic effect for synthesized samples even for concentration higher than 800 μg/mL. Hence, CeO₂-NPs were synthesized using a natural source; the procedure was rapid with good productivity and biosynthesized nanoparticles were non-toxic.     

Photocatalytic performance of yttrium-doped CNT-ZnO nanoflowers synthesized from hydrothermal method

We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs) from the hydrothermal method at 130 °C. The effect of Y³⁺-concentrations in nanostructured CNT-YZO was determined in terms of the photocatalytic degradation of methylene blue (MB). Microstructural analysis showed the hexagonal cubic structure of ZnO regardless of Y-concentration or the addition of CNTs during the nucleation and growth. The specific surface area, total pore volume, and mean pore diameter of typical CNT-YZO NFs were observed to be 36.109 m²/g, 0.162 cm³/g, and 17.932 nm, respectively. The photocatalytic degradation performance of CNT-YZO NFs improved due to increase reactive sites of the catalyst and reduced recombination of photo-induced carriers. The surface-area normalized first-order decomposition rates (r/m²) of CNT-YZO NFs showed the highest photocatalytic degradation (99%). The CNT-YZO has produced a new kind of material for the photocatalytic degradation under the irradiation of visible light using a solar simulator.     

An effective nanocomposite of polyaniline and ZnO: preparation,characterizations, and its photocatalytic activity

The polyaniline/zinc oxide (PANI/ZnO) nanocomposites were prepared by in situ polymerization of aniline monomer with ZnO nanomaterials and applied as a photocatalyst for the degradation of methylene blue (MB) dye. The morphological observations elicited the agglomerations of PANI sheets which occurred due to the interaction between PANI and ZnO nanomaterials in PANI/ZnO nanocomposites. As compared to pristine PANI, the UV–vis spectra exhibited that the absorption peak of π–π* transitions considerably shifted to higher wavelength at 360 nm from 325 nm in the nanocomposites. The photocatalytic activity results indicated the substantial degradation of MB dye by ~76% over the surface of PANI/ZnO nanocomposite catalyst under light illumination. The PANI/ZnO nanocomposites showed three times higher photocatalytic activity to MB dye degradation compared to pristine PANI might due to high photogenerated electron (ē)–hole (h⁺) pairs charge separation.     

The surface modification of spherical ZnO with Ag nanoparticles: A novel agent,biogenic synthesis,catalytic and antibacterial activities

Nowadays, the industrial wastewater pollutants including toxic dyes and pathogenic microbes have caused serious environmental contaminations and human health problems. In the present study, eco-friendly and facile green synthesis of Ag modified ZnO nanoparticles (ZnO-Ag NPs) using Crataegus monogyna (C. monogyna) extract (ZnO-Ag@CME NPs) is reported. The morphology and structure of the as-biosynthesized product were characterized by field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), differential reflectance spectroscopy (DRS), dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS) techniques. TEM and FESEM images confirmed the oval and spherical-like structure of the products with a size of 55–70 nm. The EDS analysis confirmed the presence of Zn, Ag, and O elements in the biosynthesized product. The photocatalytic results showed ZnO-Ag@CME NPs were degraded (89.8% and 75.3%) and (94.2% and 84.7%) of methyl orange (MO) and basic violet 10 (BV10), under UV and sunlight irradiations, respectively. The Ag modified ZnO nanoparticles exhibited enhanced catalytic activity towards organic pollutants, and showed better performance than the pure ZnO nanoparticles under UV and sunlight irradiations. This performance was probably due to the presence of silver nanoparticles as a plasmonic material. Antibacterial activity was performed against different bacteria. ZnO-Ag@CME NPs showed high antibacterial activity against K. pneumoniae, S. typhimurium, P. vulgaris, S. mitis, and S. faecalis with MIC values of 50, 12.5, 12.5, 12.5, and 12.45 µg/mL, respectively. All in all, the present investigation suggests a promising method to achieve high-efficiency antibacterial and catalytic performance.     

Synthesis and characterization of magnetite nanoparticles for photocatalysis of nitrobenzene

The present work shows the photocatalytic degradation of nitrobenzene (NB) using Fe₃O₄ magnetic nanoparticles (MNP) as a photocatalyst in the presence of UV light. The MNP were synthesized by an ultrasonic-assisted reverse co-precipitation (US-RP) method using FeSO₄, FeCl₃ and NH₄OH as precursors. The prepared nanoparticles were characterized by UV–vis spectroscopy, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Dynamic light scattering (DLS), Zeta potential, Vibrating sample magnetometer (VSM) and Magnetic thermogravimetric analysis (MTGA). The successive decrement in the absorbance at 265 nm shows the effective decrease in NB concentration measured by UV–vis spectroscopy. The reaction intermediates detected by gas chromatography/mass spectrum (GC/MS) were 2-nitrophenol (2-NPh), 3-nitrophenol (3-NPh) and 4-nitrophenol (4-NPh). The prepared MNP showed an optimal NB degradation at an initial pH of 2 and 100 ppm of the photocatalyst.     

Enzymes and phytochemicals from neem extract robustly tuned the photocatalytic activity of ZnO for the degradation of malachite green (MG) in aqueous media

The malachite green (MG) is very difficult to degrade in water; thus, it needs an efficient photocatalyst. In this study, neem extract was used to tune the surface and crystal properties of ZnO nanostructures for the photodegradation of MG. The biosynthesized ZnO samples were prepared by hydrothermal method in the presence of 5, 10 and 15 mL of neem extract. The structural characterization has shown nanoparticle like morphology of ZnO as revealed by scanning electron microscopy (SEM) and hexagonal phase was confirmed by powder X-ray diffraction (XRD) technique. The XRD analysis has shown a shift in the 2 theta towards lower angle for ZnO with increasing amount of neem extract. Also, the crystallite particle size of ZnO was decreased with increasing neem extract. The UV–visible spectroscopy has shown the decrease in the optical band gap of ZnO, and the lowest band gap is possessed by ZnO sample produced with 15 mL of neem extract. The ZnO sample obtained with 15 mL of neem extract has shown approximately 99% degradation efficiency for MG for 70 min in aqueous solution. The superior photocatalytic activity of ZnO sample with 15 mL of neem extract could be attributed from the decrease in charge recombination rate due to the decreased optical band gap and particle size.

     

In-situ oxidative polymerization of aniline on hydrothermally synthesized MoSe2 for enhanced photocatalytic degradation of organic dyes

In this paper, we report synthesis of MoSe₂-polyaniline by in-situ polymerization method. Simple and eco-friendly hydrothermal technique is used for the synthesis of MoSe₂. Sample characterizations were done using Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), UV–vis Spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR) and Raman Spectroscopy. Photocatalytic dye degradation was performed using nanocomposite on Methylene blue (MB) and Methyl orange (MO). Photocatalytic degradation efficiency (?) was found to be ～65% and ～94% for MB and MO, respectively. Reaction kinetics were studied and fitted well with pseudo first order model because of the mesoporous structure of polyaniline (PANI). Material reusability and regenerability was also checked for number of cycles.     

Synthesis and characterization of ternary nanocomposites of TiO2/rGO/CdS as an efficient catalyst for photo-degradation of methyl orange

Novel ternary composite photocatalysts have been successfully prepared by TiO₂ nanofibers, reduced graphene oxide, and CdS nanoparticles (TiO₂/rGO/CdS) by using electrospinning technique with easy chemical methods. The structures and their properties are examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The structural characterization of the composite reveals that pure TiO₂ NFs and CdS NPs crystalline very well and the reduced graphene oxide is tightly composed with TiO₂ NFs and CdS Nps. The photodegradation of methyl orange (MO) under UV light illumination is significantly enhanced compared with that of bare materials. This ternary composite degrades methyl orange within 75 min. The enhanced photocatalytic degradation performance resulted from effective separation of e–h pairs with rGO sheets and also contributed for high rate degradation efficiency. This novel ternary composite has a potential application of wastewater purification and utilization for energy conversions.     

Green synthesis of ZnO nanoparticles using aqueous Brassica oleracea L. var. italica and the photocatalytic activity

ABSTRACT

This study reports the synthesis of ZnO nanoparticles using the aqueous solution of broccoli extract. The nanoparticles, represented as broc-ZnO (with broccoli extract) and nb-ZnO (without broccoli extract), were obtained after calcination. The nanoparticles were characterized using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier Transform infra-red (FTIR), Energy dispersive spectroscopy (EDX), UV-visible spectroscopy (UV) and Photoluminescence (PL). Hexagonal phases were identified for both nanoparticles, while average crystallite sizes of 14 and 17?nm for broc-ZnO and nb-ZnO, respectively, were obtained. UV studies indicated the bandgap of the broc-ZnO and nb-ZnO as 4.09 and 3.87?eV, respectively. A plausible mechanism for the synthesis of the nanoparticles was suggested. The photocatalytic efficiency of broc-ZnO, obtained via the broccoli extract, was evaluated by studying its photo-enhanced catalytic activity against methylene blue (MB) and phenol red (PR), under UV light irradiation and 74% and 71% degradation efficiency of the successive dyes were achieved.     

Development of versatile CdMoO4/g-C3N4 nanocomposite for enhanced photoelectrochemical oxygen evolution reaction and photocatalytic dye degradation applications

Fabrication of an efficient, stable, and versatile photocatalysts for the energy and environment remediation applications is an urgent task for the current researchers. In this work, we have successfully synthesized a versatile hybrid photocatalysts, i.e.; CdMoO₄/g-C₃N₄ (CMO/CN) by a facile and simple one-pot in-situ hydrothermal method. Here CdMoO₄ (CMO) microspheres were deposited on the g-C₃N₄ (CN) sheets. Fabricated CN, CMO, and CMO/CN composite photocatalysts were analyzed with various characterization techniques like UV–visible diffuse reflectance spectra (UV–Vis DRS), photoluminescence spectroscopy (PL), time-resolved fluorescence lifetime (TRFL), electrochemical impedance spectroscopy (EIS), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX), transmission electron microscope (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The results reveal that the formation of a strong heterojunction between two semiconductors leads to the formation of active photocatalyst. Furthermore, as-synthesized materials were tested for the photoelectrocatalytic (PEC) oxygen evolution reactions (OERs) in acidic medium, and photocatalytic (PC) degradation of methylene blue (MB) under light irradiation. Among all tested samples, CMO/CN-10 has shown the highest current density 52.74 mA cm^?2 at 1.95 V with lowest over potential of 0.70 mV on glassy carbon electrode for OER in acidic medium under the light irradiation. The PC degradation rate constant of CMO/CN-10 composite in MB solution is k = 2.0 × 10^?2 min^?1, whereas for the pure CMO and CN degradation rate constant is k = 5.7 × 10^?3 min^?1 and k = 1.2 × 10^?2 min^?1, respectively. This enhancement in PEC and PC properties is due to the fast migration of photo-induced electrons in the case of CMO/CN-10 nanocomposite. Trapping experiment results reveal the major reactive species for PC degradation of MB is ?OH (hydroxyl radicals) and h⁺ (holes), respectively, and suitable PC reaction mechanism also proposed for CMO/CN-10 composites. Based on the above remarkable results, it would be a potential nanocomposite for the PEC oxygen evolution and PC degradation of MB under light illumination.     

Fabrication of Co + F Doped ZnO Films for Improved Visible Light Responsive Photocatalysis

The aim of this work is to investigate the efficacy of nebulizer sprayed ZnO–Co–F thin films for degrading the methylene blue (MB) aqueous solution under visible light irradiation. The physical properties of the prepared samples like structural, surface morphological and optical properties are studied using X-ray diffractometer (XRD), Scanning Electron Microscope (FESEM), UV-vis NIR spectrometer, spctroflurometer (PL) and Fourier Transform Infrared spectrometer (FTIR). The photocatalytic studies revealed that ZnO–Co–F film exhibited superior degradation efficiency over ZnO–Co and ZnO against MB as evinced by the degradation rate constants, 0.0782, 0.0475 and 0.0289 min^–1, respectively. This study showed that Co + F doping helps to remove the major limitations of ZnO and thereby leads towards better visible light activity. The structural and optical studies revealed the proper incorporation of Co²⁺ and F^– ions into the ZnO lattice and the reduction in band gap. PL emission confirmed that Co + F doping reduces the electronhole recombination rate and increases the availability of free carriers.     

Catechin mediated green synthesis of Au nanoparticles: Experimental and theoretical approaches to the determination HOMO-LUMO energy gap and reactivity indexes for the (+)-epicatechin (2S, 3S)

This work suggests a green method for synthesizing Au nanoparticles (AuNPs) using the aqueous extract of Salix aegyptiaca extract. The mechanism of green synthesized AuNPs was examined by molecular electrostatic potential (MEP) calculations. AuNPs were characterized with different techniques such as Ultraviolet–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, X-ray diffraction (XRD), and Transmission electron microscopy (TEM). Electrochemical investigation of modified glassy carbon electrode using AuNPs (AuNPs/GCE) shows that the electronic transmission rate between the modified electrode and [Fe (CN)₆]^3?/4? increased. Process of oxidation, energy gap, and chemical reactivity indexes of the (+)-epicatechin (2S,3S) were investigated using electrochemical techniques (cyclic voltammetry (CV) and differential pulse voltammetry (DPV) as well as UV–Visible spectroscopy and compared with quantum mechanical calculations. DPV and CV were used to obtain HOMO energies of the (+)-epicatechin (2S,3S), an optical energy gap was obtained from the UV–Vis spectroscopy. Frontier molecular orbitals analysis (FMO) and reactivity indexes such as chemical hardness (?), electrophilicity (?), electronic chemical potential (μ), electron acceptor power (?⁺), electron donor power (?^?) were determined with functional theory (DFT) calculations. In summary, the HOMO energy obtained from the experimental analyses (E_HOMO (from DPV) = -5.24 eV, and E_HOMO (from CV) = -5.28 eV) has a relative agreement with the HOMO energy calculated by B3LYP/6–31 g (d, p) including the solvent effect (water) (E_HOMO (from B3LYP) = -5.75 eV). Also, UV–Vis spectroscopy gives the bandgap energy equal to 4.31 eV, while the 4.13 eV is calculated by TD-DFT-b3lyp/6–31 + g(d).     

Green synthesis of ZnO and Co-ZnO using Brassica rapa leave’s extract and their activities as antioxidant agents,efficient adsorbents,and dye removal agents

The wastewater released from industries contains many harmful materials like organic dyes and toxic metal ions which badly affect our environment. Nanotechnology is one of the unique approaches to reducing these chemicals. In current research work monometallic ZnO and Co-ZnO bimetallic NPs were synthesized from Brassica rapa leave’s extract and then these were employed for the elimination of methylene blue (MB) and metal ions of Cu (II). Characterization was done by several analytical techniques such as EDX, FTIR, UV–Visible spectroscopy, SEM and XRD. The average diameter of ZnO and Co-ZnO BMNPs was found to be 32.94 nm and 13.82 nm assessed by XRD analysis. The SEM investigation revealed that the produced NPs had a spherical shape. Three distinct methods have opted to determine the antioxidant potential of synthesized NPs. Different factors like pH, contact time, NPs conc., dye conc. and temperature were studied for the elimination of dye while for the eradication of Cu (II) ions; pH, contact time, NPs conc. and adsorbate doses were studied. Adsorption isotherm and kinetic studies were employed for MB and Cu (II) ions elimination while thermodynamic studies were also done for the elimination of MB.