Designing a TiO2-MoO3-BMIMBr nanocomposite by a solvohydrothermal method using an ionic liquid aqueous mixture: an ultra high sensitive acetaminophen sensor.

This study shows a simplistic, efficient procedure to synthesize TiO2-MoO3-BMIMBr nanocomposites. Powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy have all been used to completely analyse the materials. The detection of acetaminophen (AC) has been examined at a modified glassy carbon electrode with TiO2-MoO3-BMIMBr nanocomposites. Moreover, the electrochemical behavior of the nanocomposite modified electrode has been studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The linear response of AC was observed in the range 8.26-124.03 nM. The sensitivity and detection limits (S/N = 3) were found to be 1.16 µA L mol-1 cm-2 and 11.54 nM by CV and 24 µA L mol-1 cm-2 and 8.16 nM by DPV respectively.

Structure-engineering of core-shell ZnCo2O4@NiO composites for high-performance asymmetric supercapacitors.

The implementation of a structure-designed strategy to construct hierarchical architectures of multicomponent metal oxide-based electrode materials for energy storage devices is in the limelight. Herein, we report NiO nanoflakes impregnated on ZnCo2O4 nanorod arrays as ZnCo2O4@NiO core-shell structures on a flexible stainless-steel mesh substrate, fabricated by a simple, cost-effective and environmentally friendly reflux condensation method. The core-shell structure of ZnCo2O4@NiO is used as an electrode material in a supercapacitor as it provides a high specific surface area (134.79 m2 g-1) offering high electroactive sites for a redox reaction, reduces the electron and ion diffusion path, and promotes an efficient contact between the electroactive material and electrolyte. The binder-free ZnCo2O4@NiO electrode delivers a high specific capacitance of 882 F g-1 at 4 mA cm-2 current density and exhibits remarkable cycling stability (∼85% initial capacitance retention after 5000 charge-discharge cycles at 10 mA cm-2). The asymmetric supercapacitor device ZnCo2O4@NiO//rGO delivered a maximum energy density of 46.66 W h kg-1 at a power density of 800 W kg-1. The device exhibited 90.20% capacitance retention after 4000 cycles. These results indicate that the ZnCo2O4@NiO architecture electrode is a promising functional material for energy storage devices.

Structural refinement and electrochemical properties of one dimensional (ZnO NRs)1-x(CNs)x functional hybrids for serotonin sensing studies.

Herein, the efficient serotonin (5-HT) sensing studies have been conducted using the (ZnO NRs)1-x(CNs)x nanocomposites (NCs) having appropriate structural and electrochemical properties. Initially, the different compositions of ZnO nanorods (NRs), with varying content of carbon nanostructures (CNs=MWCNTs and RGO), are prepared using simple in-situ wet chemical method and thereafter these NCs have been characterized for physico-chemical properties in correlation to the 5-HT sensing activity. XRD Rietveld refinement studies reveal the hexagonal Wurtzite ZnO NRs oriented in (101) direction with space group 'P63mc' and both orientation as well as phase of ZnO NRs are also retained in the NCs due to the small content of CNs. The interconnectivity between the ZnO NRs with CNs through different functional moieties is also studied using FTIR analysis; while phases of the constituents are confirmed through Raman analysis. FESEM images of the bare/NCs show hexagonal shaped rods with higher aspect ratio (4.87) to that of others. BET analysis and EIS measurements reveal the higher surface area (97.895 m2/g), lower charge transfer resistance (16.2 kΩ) for the ZCNT 0.1 NCs to that of other NCs or bare material. Thereafter, the prepared NCs are deposited on the screen printed carbon electrode (SPCE) using chitosan as cross-linked agent for 5-HT sensing studies; conducted through cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements. Among the various composites, ZCNT0.1 NCs based electrodes exhibit higher sensing activity towards 5-HT in accordance to its higher surface area, lower particle size and lower charge transfer resistance. SWV measurements provide a wide linear response range (7.5-300 µM); lower limit of detection (0.66 µM), excellent limit of quantification (2.19 µM) and good reproducibility to ZCNT 0.1 NCs as compared to others for 5-HT sensing studies.

Synthesis of Ni2+ ion doped ZnO-MWCNTs nanocomposites using an in situ sol-gel method: an ultra sensitive non-enzymatic uric acid sensing electrode material.

Nickel (Ni2+) ion doped zinc oxide-multi-wall carbon nanotubes (NZC) with different composition ratios of MWCNTs (from 0.01 to 0.1 wt%) are synthesized through an in situ sol-gel method. The synthesized NZC nanocomposites (NCs) are used as electrode materials with glassy carbon electrodes (GCEs) for electrochemical detection of uric acid (UA). The cyclic voltammogram of the representative NZC 0.1 modified GCE (NZC 0.1/GCE) revealed the highest electrochemical sensing activity towards the oxidation of UA at 0.37 V in 0.2 M phosphate buffer solution (PBS) having pH 7.4 ± 0.02. The limit of detection (LOD) and limit of quantification (LOQ) for the NZC 0.1/GCE are determined to be 5.72 nM and 19.00 nM (S/N = 3) respectively, which is the lowest compared to the literature values reported for enzymatic and non-enzymatic detection techniques. The synergistic effect of NZC 0.1 NCs is proposed as one of the factors for the enhanced electrochemical oxidation of UA complemented by the phase, lattice parameters, functional groups, morphology, elemental compositions, types of bonding and specific surface area with pore size ascertained using various techniques. The synthesized NZC 0.1 NCs are further proposed as selective electrode materials for the electrochemical detection of UA as authenticated further by performing interference tests with other metabolites such as ascorbic acid (AA), dopamine (DA) and d-glucose. The optimized electrochemical studies are further adopted for sensing of UA from human excretion samples using NZC 0.1 NCs.

Swollen liquid crystalline mesophase assisted synthesis of GO-PANI nanocomposite as a fluorescent probe for purines.

This article focuses on the use of graphene oxide-polyaniline (GO-PANI) nanocomposite as fluorescent probe for sensing of adenine (A) and guanine (G). Swollen liquid crystalline mesophase were used for the synthesis of graphene oxide-polyaniline nanocomposite. GO-PANI nanocomposite showed enhanced fluorescent at 441 nm (ƛ excitation = 361 nm) on interaction of purines viz A and G solutions in dimethyl sulfoxide, GO exhibited quenching at 540 nm (ƛ excitation = 261 nm). The fluorescence emission spectra of GO-PANI nanocomposite and GO were recorded in the the pressence of A and G concentrations upto 1.2 × 10-4 M. The limits of detection (LOD) calculated from the concentration dependence study for GO-PANI nanocomposite and GO are 7.5 × 10-6 M and 13.4 × 10-6 M respectively. The LOD in the case of GO is identical for both A (13.0 × 10-6) and G (13.6 × 10-6 M). The binding constant (Kb) determined for GO-PANI with purines are in the range of 0.05-0.08 × 103 M-1 which is higher in the case of GO (2.42-7.52 × 103 M-1). The lifetime measurement demonstrates, an excited state interaction of GO-PANI nanocomposite and GO with purines. This is evident from the increasing lifetime from 4.3 ns to 29.2 ns for GO-PANI nanocomposite, while 17.5 ns to 37.2 ns for GO respectively. The relatively short lifetime of the GO-PANI nanocomposite in comparison with GO suggest an electronic charge dissipation of the excited state between polyaniline and graphene oxide possibly due to the alignment of polyaniline on the graphene oxide sheet. The photopysical properties of GO-PANI nanocomposite and GO observed in this study is new and has potential for application as fluorescent probe for the detection of purines.