Green synthesis and characterization of RGO/Cu nanocomposites as photocatalytic degradation of organic pollutants in waste-water

Recently, nanocomposite photocatalysts based on semiconductors have attracted much attention due to their suitable bandgap. Combination of tow of several semiconductors can slow down the electron-hole recombination. In this regard, we have depicted an eco-friendly and green fabrication technique to synthesize RGO/Cu nanocomposite by the reduction of graphene oxide and Cu²⁺ ion utilizing spearmint extract as a reductant and capping agent. The sample was identified by FTIR, XRD, FESEM, EDS, HRTEM, and CV. The results of photocatalytic performance revealed that RGO/Cu is an efficient catalyst for degrading organic pollutants. This compound can eliminate Rhodamine B (RhB) and Methylene blue (MB) 91.0% and 72.0%, respectively.     

Green synthesis of DyBa2Fe3O7.988/DyFeO3 nanocomposites using almond extract with dual eco-friendly applications: Photocatalytic and antibacterial activities

For the first time, photocatalytical and antibacterial activities of DyBa₂Fe₃O_7.988/DyFeO₃ (Dy-Ba-Fe-O) nanocomposites as eco-friendly applications of this compound was studied in the same time. Since the applications of this compound are eco-friendly, ultrasound technique was chosen as the synthesis method. Achieving the pure product with good crystallinity with the lowest energy consumption can be considered as one of the advantages of this work. Using the almond core extract as a natural reagent was another reason for consideration this method as a green process. Band gap of this nanocomposite was estimated about 2.6 eV that showed this product can be used as a visible-active photocatalyst. Rhodamin-B dye as an organic pollutant model using the as-prepared nanocomposite was degraded about 72% that was a considerable result under visible irradiation. Elimination of microorganisms was studied by disc diffusion to recognize the sensitivity of bacterial (Staphylococcus aureus, Bacillus subtilis, E. coli, K. pneumonia and P. aeruginosa) strains the manufactured. The results confirmed that DyBa₂Fe₃O_7.988/DyFeO₃ (DBFeO) nanocomposites can be used as an antibacterial agent because of the manifested strong antibacterial ability upon Gram-negative pathogens such as K. pneumonia and E. coli. The properties of this product were characterized by different analyses including SEM, XRD, EDS, FT-IR, DRS and TEM.     

TmVO4/Fe2O3 nanocomposites: Sonochemical synthesis,characterization, and investigation of photocatalytic activity

Today, a unique method of treating environmental contaminants is drawing considerable attention. Organic dyes are significant wastes from myriad industries, including paper, food, and textiles, which have become a serious environmental concern and have the potential to be toxic to humans and living organisms. This study demonstrates the fabrication and characterization of thulium vanadate (TmVO₄) nanostructures and TmVO₄/Fe₂O₃ nanocomposites that were effectively applied in the photodecomposition efficiency of cationic and anionic organic contaminants. The TmVO₄/Fe₂O₃ nanocomposites were prepared through a sonochemical method, and triethylenetetramine (TETA) was employed as a precipitating and capping agent. The tests were performed using a probe as a sonication source (60 W, 18 kHz). The impact of TmVO₄ content (5, 10, 15, and 30%) on the modification of binary nanocomposites was studied in terms of morphological, optical, and photocatalytic properties. The recyclable magnetic TmVO₄/Fe₂O₃ nanocomposites with 15% TmVO₄ achieve 68.3% of eriochrome black t (EBT) utilizing visible origin. More notably, the binary TmVO₄/Fe₂O₃ nanocomposites reveal higher photocatalytic activity than the pure TmVO₄ and Fe₂O₃ nanoparticles.     

Green synthesis and characterization of SnO2, CuO,Fe2O3/activated carbon nanocomposites and their application in electrochemical hydrogen storage

The goal of this study is to produce environmentally friendly nanomaterials that have a high hydrogen storage capacity. The researchers in this study used inexpensive natural bitumen to produce activated carbon (substratum) and a green solution synthesis combustion method to produce CuO, Fe₂O₃, and SnO₂ nanoparticles using a Mint extract as the source material. Metal oxides such as CuO, Fe₂O₃ and SnO₂ are used to increase hydrogen storage capacity and Columbic efficiency. AC and AC/SnO₂, AC/CuO, and AC/Fe₂O₃ nanocomposites have been confirmed via XRD (X-ray diffraction), TEM (transmission electron microscopy), EDX (energy-dispersive X-rays), FT-IR (fourier transform infrared), scanning electron microscope (SEM), and adsorption and desorption analysis of N₂ (BET). In terms of discharge capacity, AC/CuO, AC/Fe₂O₃, and AC/SnO₂ display respective capacities of 2250, 2500, and 3600 mAh/g after 20 cycles, respectively. Of all the sample materials, the AC/SnO₂ nanocomposite with the highest hydrogen storage capacity has the lowest Columbic efficiency. This implies that a sample with 54% Columbic efficiency, such as AC/CuO nanocomposite, is a more suitable specimen.     

Facile electrochemical fabrication of magnetic Fe3O4 for electrocatalytic synthesis of ammonia used for hydrogen storage application

Ammonia (NH₃) offers extensive applications in industrial production; moreover, it is a potential carrier for hydrogen energy and an eco-friendly fuel. Electrocatalytic synthesis of NH₃ has drawn increasing research attention, wherein an excellent electrocatalyst plays a vital role. Iron (Fe) oxide nanomaterials with their high activity and cost effectiveness of its raw material Fe, have received significant attention in electrocatalytic N₂ reduction reaction (NRR) to synthesize NH₃. This study reports a rapid and cost-effective electrochemical method for synthesizing magnetic Fe₃O₄ nanoparticles, achieving gram-level production under ambient conditions. The synthesized magnetic Fe₃O₄ nanoparticles as electrocatalyst for NRR, achieved excellent faradaic efficiency of 16.9% and an optimal NH₃ yield of 12.09 μg h^?1 mg^?1_cat. at ?0.15 V (versus the reversible hydrogen electrode (RHE)) in 0.1 M Na₂SO₄. Besides, density functional theory (DFT) calculations indicate that the N≡N bond was fully activated, and the NRR proceeds mainly along the alternating hydrogenation pathway.     

Using pomegranate peel powders as a new capping agent for synthesis of CuO/ZnO/Al2O3 nanostructures; enhancement of visible light photocatalytic activity

CuO/ZnO/Al₂O₃ (CZA) nanoclusters were successfully synthesized via a facial and green method in the presence of pomegranate. The structural analysis of the samples confirmed the formation of CZO nanostructures in the range of 14–17 nm. The morphological studies of the samples indicated that, the shape and the particle size of the CZO nanoclusters depend on the sources, ratio of the cationic sources, time and heating temperature. The photocatalytic properties of the CZO nanostructures were obtained using photooxidation of azo dyes; Methyl orange, Methylene blue and Methyl red. The photocatalytic activity of the sample shows about 85% of azo dyes degradation after 75 min of visible light irradiations. The results were clearly demonstrated that the pure CZA nanoparticles can be used as a potential photocatalyst under visible lights for removal of contaminants.     

Enhanced ammonia synthesis activity of Ru/Ba5Ta4O15 catalyst by reduction of Ba5Ta4O15 with CaH2

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Investigate of electrochemical hydrogen storage and coulombic efficiency of NiAl2O4/NiO synthesized by cationic,anionic and polymeric surfactants: Green synthesis and characterization

In this work, NiAl₂O₄/NiO nanostructures organized with olive leaf extract have been used in hydrogen storage due to the importance of hydrogen storage and green synthesis of nanoparticles. The synthesized NiAl₂O₄/NiO nanostructures have been characterized by using XRD, EDS, FT-IR and their morphology, porosity are investigated with SEM and BET, respectively. To improve the performance of hydrogen storage of NiAl₂O₄/NiO spinel have been used cationic (CTAB), anionic (SDS) and polymeric (PVP) surfactants in the preparation of nickel aluminate. The use of polymeric surfactants (PVP) increased the hydrogen storage capacity from 1100mAh/g (for synthesized without surfactant)to 3000 mAh/g and also improved the Columbic efficiency from 55 to 75%.     

Design of Ni/La2O3 catalysts for dry reforming of methane: Understanding the impact of synthesis methods

Fine-tuning of materials properties, particularly the catalytic properties, through innovative synthesis procedures has gained an increased research interest in the last decades. It is well known that synthesis procedures have considerable impact on the physio-chemical properties of the synthesized materials even if the chemical composition is maintained. Herein, we investigated the impact of selected synthesis methods on the catalytic performance of Ni/La₂O₃ for the dry reforming of methane (DRM), a challenging reaction known for severe coking. Although this catalyst has been frequently studied for DRM, however, tuning the structure-activity relationship by varying the synthesis routes has not been reported. Herein, the chosen synthesis techniques; for example the solution combustion synthesis (Ni/La-SC), sol-gel (Ni/La-SG), homogeneous precipitation (Ni/La-HP), solvothermal (Ni/La-ST), and modified oleylamine-assisted synthesis (Ni/La-ME); considerably affected the morphology, metal support interaction (MSI), and surface area of Ni/La₂O₃ catalysts leading to variation in their performance for DRM. The investigated catalysts were thoroughly characterized by using SEM-EDX, TEM, N₂-physisorption, XRD, XPS, and H₂-TPR to understand the structural properties. Their catalytic performance towards the DRM was evaluated by varying the temperature between 550 and 800 °C. DRM experiments demonstrated that among the studied catalysts, Ni/La-SC showed the best performance for DRM with a high catalytic activity and coking resistance. For instance, Ni/La-SC revealed the highest CO₂ and CH₄ conversions i.e. 97.9 ± 1.5% and 96.6 ± 1.8%, respectively at 800 °C. The same sample revealed the highest hydrogen yield i.e. 71.9% and the highest H₂/CO ratio i.e. 1.03 ± 0.013 at the same temperature. The results revealed that Ni/La-SC demonstrated the lowest increment (20.9%) in the Ni crystallite size after DRM reaction, highest durability, and the lowest rate of coke formation (42 ± 5.2 mg C/g_catalyst) over an operating period of 100 h at 800 °C. The outstanding performance of Ni/La-SC catalyst was credited to the small crystallite size of Ni, high Ni⁰/Ni²⁺ ratio, high BET area, and a good dispersion of nickel sites over the La₂O₃ support. The obtained results may open new frontiers for size and shape-controlled synthesis of nanostructured metals/metal oxides catalysts with controllable morphologies and dispersion that can lead to desirable catalytic properties.     

A facile one-step synthesis of single crystalline hierarchical WO3 with enhanced activity for photoelectrochemical solar water oxidation

Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO₃) has been synthesized via a straightforward, template-free, hydrothermal route from ammonium metatungstate hydrate and implemented in photoanode fabrication for solar water oxidation in photoelectrochemical cells and photocatalytic oxidation of organic pollutant. The flower-like WO₃ micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single-crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. Time-dependent experiments have been conducted to demonstrate their morphology evolution. The hierarchical architecture based photoanodes produce higher photocurrent (2-fold high) than the nanoparticles based photoanodes from solar water oxidation. The photon to current conversion efficiency achieved with the hierarchical architectures is 45% at 400 nm. The enhanced activity can be attributed to improved charge-separation by superior charge transportation through single-crystalline 1D building blocks.