Construction of MoS2/CND-WO3 Ternary Composite for Photocatalytic Hydrogen Evolution

Evaluation of cytotoxic potential of silver nanoparticles biosynthesized using essential oils of Jasminum sambac against breast cancer and bacterial cells

Essential oils (EOs) which cover about 91% whole biomolecules formulated from Jasminum sambac leaves based on Gas chromatography-mass spectrometry were employed to identify structures. EOs were observed as good agents in the preparation of Silver nanoparticles (AgNPs) through the proposed mechanism that was attempted to interpret the pathway of the bio-preparation process. The characterization of EOs-AgNPs carried via ultraviolet-visible to reveal surface plasmon resonance at 420 nm, Fourier transform infrared to observe functional groups EOs compared to EOs-AgNPs. X-ray diffraction (XRD) revealed a broad chart owing to the small size of AgNPs in average size less than 10 nm calculated relying on image J software, spherical AgNPs with a small dispersive size observed by transmission electron microscopy. Quasi near spherical surface morphology of EOs-AgNPs had detected by field emission scanning electron microscope. EOs-AgNPs were assessed for their antibacterial potential against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria as suppressing bacterial agents. EOs-AgNPs had their anti-breast cancer MCF-7 cell line ability investigated by DNA fragmentation; cycle flow cytometry (apoptosis) at half maximal inhibitory concentration (IC50) was determined at 260 µg/mL which has been stated by cytotoxicity (MTT) assay. EOs-AgNPs have antibacterial and anticancer therapeutic potential, and it is safe, inexpensive, and scalable in the nanoscale range.

MoS2-Based Nanocomposites for Photocatalytic Hydrogen Evolution and Carbon Dioxide Reduction

Photocatalysis is a facile and sustainable approach for energy conversion and environmental remediation by generating solar fuels from water splitting. Due to their two-dimensional (2D) layered structure and excellent physicochemical properties, molybdenum disulfide (MoS₂) has been effectively utilized in photocatalytic H₂ evolution reaction (HER) and CO₂ reduction. The photocatalytic efficiency of MoS₂ greatly depends on the active edge sites present in their layered structure. Modifications like reducing the layer numbers, creating defective structures, and adopting different morphologies produce more unsaturated S atoms as active edge sites. Hence, MoS₂ acts as a cocatalyst in nanocomposites/heterojunctions to facilitate the photogenerated electron transfer. This review highlights the role of MoS₂ as a cocatalyst for nanocomposites in H₂ evolution reaction and CO₂ reduction. The H₂ evolution activity has been described comprehensively as binary (with metal oxide, carbonaceous materials, metal sulfides, and metal-organic frameworks) and ternary composites of MoS₂. Photocatalytic CO₂ reduction is a more complex and challenging process that demands an efficient light-responsive semiconductor catalyst to tackle the thermodynamic and kinetic factors. Photocatalytic reduction of CO₂ using MoS₂ is an emerging topic and would be a cost-effective substitute for noble catalysts. Herein, we also exclusively envisioned the possibility of layered MoS₂ and its composites in this area. This review is expected to furnish an understanding of the diverse roles of MoS₂ in solar fuel generation, thus endorsing an interest in utilizing this unique layered structure to create nanostructures for future energy applications.

Lu modified ZnO/CNTs composite: A promising photocatalyst for hydrogen evolution under visible light illumination

We report high photocatalytic hydrogen evolution from water-glycerol mixture under visible light illumination using sol-gel method synthesized zinc oxide (ZnO), Lutetium (Lu) modified ZnO and Lu modified ZnO/CNTs composite. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), photocurrent transient response and electrochemical impedance spectroscopy (EIS) Nyquist studies were used to determine the reason for improved photocatalytic hydrogen evolution. The highest hydrogen evolution rate of 380 µmolh^-1 was obtained for Lu modified ZnO/CNTs composite, 3.11 times the amount generated over Lu modified ZnO and 10.5 times than using pure ZnO sample. This efficient enhancement in the photocatalytic hydrogen evolution was apparently attributed to the red shift in the optical absorption, increased charge separation, high surface area, cleavage of glycerol by Lu and synergistic effect between Lu and CNTs. Moreover, the effect of Lu and CNTs loading on the photocatalytic hydrogen evolution activity of Lu modified ZnO/CNTs was also studied under analogous experimental conditions. A mechanism of photocatalytic hydrogen evolution by Lu modified ZnO/CNTs composite was also proposed. Additionally, synthesized samples showed prolonged photostability with steady hydrogen evolution in successive cycle runs. This report might attract much attention to design highly efficient and inexpensive photocatalyst for hydrogen evolution under visible light illumination.

Green-synthesized metal nanoparticles for mosquito control: A systematic review about their toxicity on non-target organisms

Studies capturing the high efficiency of green-synthesized metal nanoparticles (NPs) in targeting mosquito vectors of the world's main infectious diseases suggest the NPs' possible utilization as bio-insecticides. However, it is necessary to confirm that these potential bio-insecticides are not harmful to non-target organisms that are often sympatric and natural enemies of the vectors of these diseases. In this systematic review, we comprehensively analyse the content of 56 publications focused on the potentially deleterious effects of NPs on these non-target organisms. Current research on biosynthesised NPs, characterization, and impact on mosquito vectors and non-target larvivorous organisms is reviewed and critically discussed. Finally, we pinpoint some major challenges that merit future investigation. Plants (87.5%) were mainly used for synthesizing NPs in the studies. NPs were found to be spherical or mainly spherical in shape with a large distribution size. In most of the included studies, NPs showed interesting mosquitocidal activity (LC₅₀ < 50 ppm). Some plant families (e.g., Meliaceae, Poaceae, Lamiaceae) have produced NPs with a particularly high larvicidal and pupicidal activity (LC₅₀ < 10 ppm). Regarding non-target organisms, most of the studies concluded that NPs were safe to them, with boosted predatory activity in NP-treated milieu. In contrast, some studies reported NP-elicited adverse effects (i.e., genotoxic, nuclear, and enzymatic effects) on these non-target organisms. This review outlines the promising mosquitocidal effects of biosynthesized NPs, recognizing that NPs' potential usage is currently limited by the harm NPs are thought pose to non-target organism. It is of utmost importance to investigate green NPs to determine whether laboratory findings have applications in the real world.

Synthesis, Characterization and Photocatalytic Activity of MoS2/ZnSe Heterostructures for the Degradation of Levofloxacin

Antibiotics have been extensively used over the last few decades. Due to their extensive usage and persistence in the environment, they are considered as emergent pollutants. It is, therefore, important to synthesize new materials for efficient antibiotic degradation. Herein, we report the MoS2/ZnSe heterostructures prepared by a simple ultrasonication method. Heterostructures were prepared with different ratios of MoS2 and ZnSe, i.e., 1:3, 1:1 and 3:1. Characterization of the heterostructures was done by UV-vis diffused reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoluminescence (PL) techniques to understand the morphology and surface chemistry. The results show that an efficient interface was formed to harness the visible light and degrade levofloxacin, which was monitored by gradual decreases in the UV-vis absorbance signal of levofloxacin. Among the prepared heterostructures and their pure counter parts, MoS2/ZnSe 3:1 (3:1 MZ) showed a better degradation activity of 73.2% as compared to pure MoS2 (29%) and ZnSe (17.1%) in the presence of visible light in a time span of two hours. The reusability studies showed that the catalytic performance of 3:1 MZ did not decrease significantly after three cycles. Moreover, the morphology and the crystal structure also remained unchanged.

Measuring the Electrical and Photonic Properties of Cobalt Oxide-Containing Composite Carbon Fibers

In this work, cobalt acetate was incorporated into polyacrylonitrile (PAN) polymer through electrospinning as the cobalt oxide source. After oxidization and pyrolysis, a PAN-derived composite carbon fiber containing cobalt oxide was obtained. Measuring the electrical and photonic properties of the composite fiber under visible light irradiation was performed to evaluate the photoelectric behavior of the composite fiber. The p-type semiconducting behavior of the composite fiber was confirmed by measuring the open circuit voltage of a photochemical fuel cell consisting of the photosensitive electrode made from the composite fiber. The application of the composite fiber for glucose sensing was demonstrated.

Photocatalytic reduction of Cr(VI) by WO3@PVP with elevated conduction band level and improved charge carrier separation property

Photocatalytic reduction of heavy metal ions is a green and promising technology which requires electrons with enough negative energy levels as well as efficient separation property from photo-generated holes of photocatalysts. For WO₃, the low conduction band edge and the severe photo-generated charge carrier recombination limited its application in photocatalytic reduction of pollutants. In this work, we prepared WO₃@PVP with PVP capped WO₃ by a simple one-step hydrothermal method, which showed an elevated energy band structure and improved charge carrier separation property. XRD, SEM, TEM, XPS, DRS, and the photocurrent density test were carried out to study the properties of the composite. Results demonstrated monoclinic WO₃ with a size of ∼100-250 nm capped by PVP was obtained, which possessed fewer lattice defects inside but more defects (W⁵⁺) on the surface. Moreover, the results of the photocatalytic experiment showed the kinetic constant of Cr(VI) reduction process on WO₃@PVP was 0.532 h^-1, which was 3.1 times higher than that on WO₃ (0.174 h^-1), demonstrating WO₃@PVP with good photocatalytic capability for Cr(VI) reduction. This can be attributed to the improved charge carrier separation performance, the improved adsorption capacity and the elevated conduction band edge of WO₃@PVP. More importantly, the energy band structure of WO₃@PVP was proved elevated with a value as high as 1.14 eV than that of WO₃ nanoparticles, which enables WO₃@PVP a promising material in the photocatalytic reduction reaction of heavy metal ions from wastewater.

Nitrogen doped carbon quantum dots and GO modified WO3 nanosheets combination as an effective visible photo catalyst

Nitrogen doped carbon quantum dots (NCQDs) based highly efficient ternary photocatalyst are fabricated by modifying surface of GO incorporated WO₃ nano-sheets. XRD confirmed the formation of monoclinicWO₃ nano-sheets. All the characteristic peaks of WO₃, GO and NCQDs are obvious in XRD patterns of WO₃/GO/NCQDs ternary photocatalysts confirming successful fabrication of the photocatalysts. SEM images showed that WO₃ host matrix is distorted after incorporation of GO and NCQDs owing to lower interfacial tension. The surface of WO₃ nano-sheets is modified with morphological defects making more active sites available. UV-vis spectra exhibited extended visible light absorption and remarkable reduction of WO₃ band gap energy. The photoluminescence spectra confirmed the efficient charge separation in NCQDs modified ternary photocatalyst. The synthesized composites were applied for the photocatalytic degradation of harmful organic dye i.e. methyl orange (MO). The ternary composites represented the excellent photocatalytic activity as compared to binary and pure WO₃ photocatalysts. This enhanced photocatalytic activity is attributed to the availability of active sites, extended light absorption in visible region and enhanced charge separation efficiency.

A tetraphenylporphyrin/WO3/exfoliated graphite nanocomposite for the photocatalytic degradation of an acid dye under visible light irradiation

Charge carrier separation in visible light photocatalytic degradation of a dye was achieved by the fabrication of a tetraphenylporphyrin/WO₃/exfoliated graphite nanocomposite.