Grape Seed Extract Assisted Synthesis of Dual-Functional Anatase TiO2 Decorated Reduced Graphene Oxide Composite for Supercapacitor Electrode Material and Visible Light Photocatalytic Degradation of Bromophenol Blue Dye.

The grape extract is a potential natural reducing agent because of its high phenolic content. The extracts of seeds, skin, and pulp of grape were prepared by digestion, grinding, and soxhlet methods and used for reducing graphene oxide (GO). The reduced GO made using the soxhlet extract of grape seed (GRGO) was hydrothermally treated with titanium dioxide (TiO2) for the synthesis of GRGO-TiO2 nanocomposite. The X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-vis, photoluminescence, and Raman spectra studies further confirmed the formation of GRGO and the GRGO-TiO2 hybrid. Scanning electron microscope and transmission electron microscope studies showed the decoration of spherical TiO2 particles (<100 nm) on the few-layered GRGO sheets. The GRGO-TiO2 hybrid was explored as a working electrode for supercapacitors and visible light photocatalyst for water decontamination. GRGO-TiO2 showed higher specific capacitance (175 F g-1) than GRGO (150 F g-1) and TiO2 (125 F g-1) in an aqueous electrolyte. GRGO-TiO2 exhibited 83.6% capacitance retention even after 2000 cycles, indicating the good stability of the material. Further, under visible light irradiation (λ > 400 nm), GRGO-TiO2 showed ∼30% higher photo-oxidation of the bromophenol blue (BPB) dye than TiO2. Also, GRGO-TiO2 decreased the total organic carbon content of BPB from 92 to 18 ppm. Overall, the soxhlet extract of grape seed was found to be a cost-effective reducing agent for the preparation of GRGO, which is a suitable material to be used in supercapacitors and photocatalysis.

Eco-friendly Synthesis of CRGO and CRGO/SnO2 Nanocomposite for Photocatalytic Degradation of Methylene Green Dye.

Reduced graphene oxide (rGO) was synthesized from a simple, cost-effective, and eco-friendly method by using Capsicum annuum (CA) as reducing agent. The rGO was mixed with SnO2 to synthesize a nanocomposite. The synthesized materials were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and UV-visible spectroscopy techniques. The SnO2-C. annuum reduced graphene oxide (CRGO) nanocomposite exhibited a photodegradation efficiency of 97.4% when employed to remove methylene green (MG) dye. The synthesized nanocomposite showed improved photodegradation ability due to its high charge transfer and separation and owing to the presence of the large surface area of the CRGO network system. Degraded water was used in the plant and animal survival study, in which the dye solution treated with CRGO nanocomposite exhibited better growth compared to that of untreated MG solution. Likewise, in the ecotoxicity study, Artemia salina and zebra fish (Danio rerio) survival was found to be enhanced with CRGO nanocomposite-treated dye solution. This finding supports the effectiveness of CRGO/SnO2 nanocomposite for the treatment of MG dye-contaminated effluent samples.

Quenching-Induced Structural Distortion of Graphitic Carbon Nitride Nanostructures: Enhanced Photocatalytic Activity and Electrochemical Hydrogen Production.

Engineered nanomaterials are emerging in the field of environmental chemistry. This study involves the analysis of the structural, electronic, crystallinity, and morphological changes in graphitic carbon nitride (g-C3N4), an engineered nanomaterial, under rapid cooling conditions. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared, Raman, band gap, and Mott-Schottky analyses strongly proved that the liquid N2-quenched sample of g-C3N4 has structural distortion. The photocatalytic efficiency of engineered g-C3N4 nanostructures was analyzed through the degradation of reactive red 120 (RR120), methylene blue (MB), rhodamine B, and bromophenol as a representative dye. The photocatalytic dye degradation efficiency was analyzed by UV-vis spectroscopy and total organic carbon (TOC) analysis. The photocatalytic efficiency of g-C3N4 under different quenching conditions included quenching at room temperature in ice and liquid N2. The degradation efficiencies are found to be 4.2, 14.7, and 82.33% for room-temperature, ice, and liquid N2 conditions, respectively. The pseudo-first-order reaction rate of N2-quenched g-C3N4 is 9 times greater than the ice-quenched g-C3N4. Further, the TOC analysis showed that 55% (MB) and 59% (RR120) of photocatalytic mineralization were achieved within a time duration of 120 min by the liquid N2-quenched g-C3N4 nanostructure. In addition, the quenched g-C3N4 electrocatalytic behavior was examined via the hydrogen (H2) evolution reaction in acidic medium. The liquid N2-quenched g-C3N4 catalyst showed a lower overpotential with high H2 evolution when compared with the other two g-C3N4-quenched samples. The results obtained provide an insight and extend the scope for the application of engineered g-C3N4 nanostructures in the degradation of organic pollutants as well as for H2 evolution.

Synthesis of reduced graphene oxide/ZnO nanocomposites using grape fruit extract and Eichhornia crassipes leaf extract and a comparative study of their photocatalytic property in degrading Rhodamine B dye.

In the present work, we report the comparative study of photocatalytic degradation of Rhodamine B (RhB) dye in aqueous solution by using ZnO-graphene nanaocomposites obtained using two different natural reducing agents namely Grape and Eichhornia crassipes. Graphene oxide (GO) was synthesized by Hummer's method followed by reduction of the graphene oxide using natural reducing agents Grape and Eichhornia crassipes. The two samples of graphene oxide (Gr-rGO and Ei-rGO) were treated with ZnO to form a rGO-ZnO nanocomposites. The dye degradation was observed by the decrease in the absorption and decolorization in the presence of visible light. The degradation efficiency was found to be dependent on the concentration of rGO-ZnO nanocomposites added to the dye solution. The Ei-rGO has a higher adsorbing capacity due to its large surface area. A degradation efficiency of 67% was achieved by ZnO alone, whereas with the rGO-ZnO nanocomposite, the photocatalytic degradation efficiency for removal of RhB dye was found to be enhanced. The degradation efficiency was 70.0% and 97.5% with Gr-rGO-ZnO and Ei-rGO-ZnO nanocomposites respectively. The enhanced photocatalytic activity of Ei-rGO-ZnO composites could be attributed to the strong interaction with the ZnO and the defect sites available in Ei-rGO. Graphical abstractGraphical abstract of the carried work.

Synthesis, Characterization and Solvatochromic Studies Using the Solvent Polarity Parameter, ENT on 2-Chloro-3-Ethylamino-1,4-Naphthoquinone.

Quinones are molecules with varied biological activities and electronic properties which are used for important applications [1, 2]. Quinone with a heteroatom substituted, namely 2-chloro-3-ethylamino-1,4-naphthoquinone (N-CAN) was synthesized and characterized by various techniques such as H1-NMR, C13-NMR, Mass spectroscopy and FT-IR spectroscopy. In this study, the solvatochromic effects on the spectral properties of 2-chloro-3-ethylamino-1,4-naphthoquinone have been investigated in different solvents taking into consideration, the solvent parameters like dielectric constant (ε) and refractive index (η) of different solvent polarities. Using Lippert-Mataga, Bakshiev's, Kawski-Chamma-Viallet and Reichardt equations, the ground state (µg) and excited state (µe) dipole moments were calculated. The angle between the excited state and ground state dipole moments were also calculated. Graphical Abstract ᅟ.

Synthesis, molecular docking and biological evaluation of novel 6-(4-(4-aminophenylsulfonyl)phenylamino)-5H-benzo[a]phenothiazin-5-one derivatives.

A novel series of 6-(4-(4-aminophenylsulfonyl)phenylamino)-5H-benzo[a]phenothiazin-5-one derivatives have been synthesized and examined for their in vitro antibacterial activity against a panel of Gram-positive and Gram-negative bacteria. Among these, N-(4-(4-(5-oxo-5H-benzo[a]phenothiazin-6-ylamino)phenylsulfonyl)phenyl)-3,5-bis(trifluoromethyl)benzamide (3n) (0.4 µg/mL) and 4-ethyl-N-(4-(4-(5-oxo-5H-benzo[a]phenothiazin-6-ylamino)phenylsulfonyl)phenyl)benzamide (3l) (0.6 µg/mL) systems exhibited a potent inhibitory activity against Gram-positive organism Bacillus subtilis, when compare to the other synthesized compounds. Sparfloxacin (9.76 µg/mL), Norfloxacin (no activity) were employed as the standard drugs. An evaluation of the cytotoxicity of the title compounds (1, 2, 3a-n) revealed that they displayed low toxicity (26-115 mg/L) against cervical cancer cell line (SiHa). The results of these studies suggest that, phenothiazin-5-one derivatives are interesting binding agents for the development of new Gram-positive and Gram-negative antibacterial agents. To understand the interactions with protein receptors, docking simulation was done with crystal structures of B.subtilis (YmaH) and histone deacetylase (HDAC8) to determine the probable binding conformation.