Mohit Saraf

A fascinating multitasking Cu-MOF/rGO hybrid for high performance supercapacitors and highly sensitive and selective electrochemical nitrite sensors

Herein, we report a multitasking Cu-MOF/rGO hybrid, fabricated by simple ultra-sonication of slow diffusion driven Cu-MOF crystals with chemically synthesized reduced graphene oxide (rGO). The molecular structure of the Cu-MOF was authenticated by single crystal X-ray studies. The prepared materials have been probed by various physicochemical characterization techniques. Due to the positive synergistic effects between Cu-MOF crystals and rGO nanosheets, the newly synthesized Cu-MOF/rGO hybrid delivers high charge storage efficiency (685.33 F g−1 at 1.6 A g−1), high energy (137.066 W h kg−1) and power density (4800.04 W kg−1) and excellent rate ability (retains 71.01% of its initial capacitance at 8 A g−1). Furthermore, the long cycle life (91.91% after 1000 cycles) of this hybrid indicates its high stability on the electrode surface. Additionally, the electrode modified with the Cu-MOF/rGO hybrid performs exceptionally towards the electrochemical detection of nitrite in a wide dynamic linear range of 3–40 000 μM (R2 = 0.99911), with a notable detection limit of 33 nm and a high sensitivity of 43.736 μA μM−1 cm−2. The versatility of the Cu-MOF/rGO modified electrode can be observed by distinguished selectivity in the presence of some common interfering species and also ability to detect nitrite in real samples.

Probing Highly Luminescent Europium-Doped Lanthanum Orthophosphate Nanorods for Strategic Applications

Herein we have established a strategy for the synthesis of highly luminescent and biocompatible europium-doped lanthanum orthophosphate (La0.85PO4Eu0.15(3+)) nanorods. The structure and morphogenesis of these nanorods have been probed by XRD, SEM, and TEM/HRTEM techniques. The XRD result confirms that the as-synthesized nanorods form in a monazite phase with a monoclinic crystal structure. Furthermore, the surface morphology shows that the synthesized nanorods have an average diameter of ∼90 nm and length of ∼2 μm. The HRTEM images show clear lattice fringes that support the presence of better crystal quality and enhanced photoluminescence hypersensitive red emission at 610 nm ((5)D0-(7)F2) upon 394 nm wavelength excitation. Furthermore, time-resolved spectroscopy and an MTT assay of these luminescent nanorods demonstrate a photoluminescent decay time of milliseconds with nontoxic behavior. Hence, these obtained results suggest that the as-synthesized luminescent nanorods could be potentially used in invisible security ink and high-contrast bioimaging applications.

Antioxidant activity of fraction of Tephrosia purpurea linn.

The ethanol extract of Tephrosia purpurea Linn. (Family: Leguminosae) was found to significantly inhibit the carbon tetrachloride-induced lipid peroxidation in vivo and superoxide generation in vivo . The ethyl acetate fraction of the same extract was studied for free radical scavenging and antilipid peroxidation activity. The IC50 values in both of these in vitro assays were found to be significantly reduced for ethyl acetate fraction compared with the ethanolic extract of the plant. The observation was further supported by comparing the in vivo antioxidant activity for both the ethanolic extract and its ethyl acetate fraction. The study concluded that the ethanolic extract of T. purpurea exhibits antioxidant activity in vivo and the ethyl acetate soluble fraction has improved antioxidant potential than the extract.

Microwave assisted fabrication of a nanostructured reduced graphene oxide (rGO)/Fe2O3 composite as a promising next generation energy storage material

Herein, we report a facile two-step process involving homogenous precipitation followed by microwave assisted reduction to fabricate a rGO–Fe2O3 composite. The applicability of the composite as an electrode material for supercapacitors has been evaluated by a cyclic voltammetry (CV) and galvanostatic charging–discharging (GCD) study. The composite displays excellent supercapacitor performance compared to bare rGO and generates a high specific capacitance of 577.5 F g−1, at a current density of 2 A g−1. A high rate performance is also observed by retaining a specific capacitance of 437.5 F g−1, at a high current density of 10 A g−1. Finally, the electrodes have been analyzed through electrochemical impedance spectroscopy (EIS) to probe the charge transfer characteristics and the results have been found to be consistent with other electrochemical measurements. The remarkable electrochemical performance of the rGO–Fe2O3 composite can be attributed to the positive synergistic effects between rGO platelets and Fe2O3 nanoparticles.

Design and construction of a ferrocene based inclined polycatenated Co-MOF for supercapacitor and dye adsorption applications

A new cobalt based inclined polycatenated metal–organic framework, {[Co4(FcDCA)4(bpy)4(H2O)6]·11H2O}n [FcDCA = 1,1′-ferrocene dicarboxylic acid and bpy = 4,4′-bipyridyl] (1), has been designed and synthesized in a facile manner. 1 can be simplified as a 2D + 2D → 3D inclined polycatenation class with Doc1/1, as authenticated by single crystal X-ray studies. Further, 1 was employed as a modifier for a glassy carbon electrode (1-GCE) without using any binders to explore its supercapacitor performance. Detailed electrochemical investigations carried out using 1-GCE reveal a specific capacitance of 446.8 F g−1 at a current density of 1.2 A g−1, with an excellent cycle life of ∼88.37% (after 800 cycles). Moreover, a high rate performance was also observed for 1-GCE (it retains 81% of its initial capacitance up to a high current density of 10 A g−1), which endorsed its good stability on the electrode surface. The results were found to be superior than those for {[Co(bpy)1.5(NO3)2]}n (2), highlighting the role of the presence of FcDCA in 1. Additionally, the notable adsorption and desorption properties of 1 towards selected Chicago Sky Blue (CSB) and Congo Red (CR) dyes confirms the candidature of 1 as a potential dye adsorbing agent.

In vitro Tocolytic activity of Sarcostemma brevistigma Wight

The effect of a chloroform soluble fraction (F-A) of the acetone extract of twigs of Sarcostemma brevistigma Wight on contractions induced by oxytocin and KCl, in the isolated rat uterine smooth muscles, has been evaluated. At concentrations of 32.8 µg/ml, the F-A significantly inhibited (P<0.001) the contractions induced by 60 mM KCl in Ca2+, containing physiological salt solution to the extent of 88.7 ± 2.2%. The F-A, at concentrations of 26.3 µg/ml, completely inhibited the rhythmic contractions induced by oxytocin in Ca2+, containing physiological salt solution. However, it failed to inhibit the contractions induced by oxytocin in Ca2+ free PSS. These results suggest that fraction F-A exhibits uterine relaxant activity, by interfering with the extracellular Ca2+.

Multifunctional porous NiCo2O4 nanorods: sensitive enzymeless glucose detection and supercapacitor properties with impedance spectroscopic investigations

We report the multipurpose nature of NiCo2O4 nanorods fabricated by a facile two-step method for high-performance glucose sensors and supercapacitors. The nanorods that were obtained were investigated by various physicochemical characterization techniques, which revealed their polycrystallinity, suitable microstructure, high porosity and thermal stability. The nanorods that were synthesized were assembled on a glassy carbon electrode (GCE) with a Nafion support via layer-by-layer assembly (Nafion/NCO/GCE or NNCOGCE). The NNCOGCE that was fabricated was employed as a working electrode for two separate applications, namely, a glucose sensor and a supercapacitor. The NNCOGCE selectively detected glucose in a short amperometric response time (3 s), with a wide dynamic linear range (0.001–0.88 mM), a notable detection limit (63 nM) and high sensitivity (4.710 μA μM−1 cm−2). Moreover, the NNCOGCE exhibited high specific capacitance (980 F g−1 at a current density of 2 A g−1) and excellent rate performance (retention of 71.42% up to 10 A g−1) with a long cycle life (retention of 92% up to 1000 cycles). Finally, the NNCOGCE was studied by electrochemical impedance spectroscopy (EIS) to investigate its charge transfer characteristics for both glucose sensor and supercapacitor applications, and the results were correlated with its amperometric sensing ability, as well as its supercapacitor performance.

Visible-Light-Induced Water Splitting Based on a Novel α-Fe2O3/CdS Heterostructure

In this work, CdS nanoparticles were grown on top of a hematite (α-Fe2O3) film as photoanodes for the photoelectrochemical water splitting. Such type of composition was chosen to enhance the electrical conductivity and photoactivity of traditionally used bare hematite nanostructures. The fabricated thin film was probed by various physicochemical, electrochemical, and optical techniques, revealing high crystallinity of the prepared nanocomposite and the presence of two distinct phases with different band gaps. Furthermore, photoassisted water splitting tests exhibit a noteworthy photocurrent of 0.6 mA/cm2 and a relatively low onset potential of 0.4 V (vs reversible hydrogen electrode) for the composite electrode. The high photocurrent generation ability was attributed to the synergistic interplay between conduction and valence band (VB) levels of CdS and α-Fe2O3, which was further interpreted by J–V curves. Finally, electrochemical impedance spectroscopy investigation of the obtained films suggests that the photogenerated holes could be transferred from the VB of α-Fe2O3 to the electrolyte more efficiently in the hybrid nanostructure.

A highly selective and sensitive chemosensor for L-tryptophan by employing a Schiff based Cu(II) complex

A new Cu(II) complex C40H38N4CuO2 (1) was synthesized and characterized by elemental analysis, mass spectrometry and also authenticated by single crystal X-ray studies. Structural analysis of 1 reveals the distorted square planar geometry around the Cu(II) centre and the presence of C–H⋯O and N–H⋯π hydrogen bonding interactions. The sensing behaviour of 1 towards L-tryptophan (L-Trp) was identified by UV-vis spectroscopic and cyclic voltammetry experiments. In the UV titration of 1 with L-Trp, four distinct isosbestic points were observed. Furthermore, on modifying the surface of the glassy carbon electrode (GCE) by 1 (1-GCE) the oxidation potential of L-Trp at +0.32 V is revealed, which is considerably lower than the values previously reported for other electrodes. Additionally, the 1-GCE can detect L-Trp with a noteworthy detection limit (185 nM), sensitivity (3.156 μA μM−1 cm−2) and with distinguished selectivity in the presence of various other amino acids. The 1-GCE also displays excellent reproducibility, repeatability and long term stability. Finally, electrochemical impedance spectroscopy (EIS) investigations were carried out to gauge the effects of modification with 1 on the characteristics of the GCE. Moreover, the molecular docking study of 1 with various proteins reveals the π–π stacking interaction with L-Trp.

Emerging Robust Heterostructure of MoS2–rGO for High-Performance Supercapacitors

The intermittent nature of renewable energy resources has led to a continuous mismatch between energy demand and supply. A possible solution to overcome this persistent problem is to design appropriate energy-storage materials. Supercapacitors based on different nanoelectrode materials have emerged as one of the promising storage devices. In this work, we investigate the supercapacitor properties of a molybdenum disulfide-reduced graphene oxide (rGO) heterostructure-based binder-free electrode, which delivered a high specific capacitance (387.6 F g-1 at 1.2 A g-1) and impressive cycling stability (virtually no loss up to 1000 cycles). In addition, the possible role of rGO in the composite toward synergistically enhanced supercapacitance has been highlighted. Moreover, an attempt has been made to correlate the electrochemical impedance spectroscopy studies with the voltammetric analyses. The performance exceeds that of the reported state-of-the-art structures.