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SnO2 is a wide bandgap photocatalyst, and Fe2O3 is susceptible to the recombination of photocharges produced is heterogenized in the form of NaFeSnO4. NaFeSnO4 with post‐spinel structure having one‐dimenisonal (1D) channel is explored first time as photocatalyst. Phase purity and structure of NaFeSnO4 was examined using X‐ray diffraction (XRD). Particle morphology, light absorption behavior, band‐gap energy estimation and surface area of NaFeSnO4 were evaluated using various instrumental techniques. Extent of charge separation and charge transfer was investigated using photoluminescence (PL) analysis and electrochemical impedance spectroscopy (EIS). Photocatalytic performance of NaFeSnO4 was examined for degradation of crystal violet dye by irradiating visible light. The photocatalytic properties of NaFeSnO4 are compared with the precursor oxides Fe2O3 and SnO2. It has been demonstrated first time that NaFeSnO4 is an efficient visible light active photocatalyst than Fe2O3 and SnO2 for degradation of crystal violet dye. [ABSTRACT FROM AUTHOR]

The exploration of inexpensive and copious materials for water splitting has not come to an end even though a lot of materials has been synthesised to cope with the high overpotential and Tafel slope. The present manuscript demonstrates fabrication and performance studies of Co3O4 and TiO2 composite (CTC) catalyst coated electrode for electrochemical water splitting. The use of CTC (Co3O4@TiO2) showed the band gap of 2.41 eV which is found to be suitable for efficient water splitting reaction. The electrode fabrication was done using CTL coated FTO glass that provided a stable cathodic electrode for overall water splitting. The detail electrochemical studies of CTC electrode were performed in 1 M KOH electrolyte solution in a three‐electrode system. The CTC exhibited lowest Tafel slope value for both hydrogen evolution reaction (HER) of 51 mV/dec and oxygen evolution reaction (OER) of 166 mV/dec, calculated at 10 mA/cm2. Moreover, the highest current density 66.59 mA/cm2 at 0.20 V and 85.84 mA/cm2 at 1.85 V was observed for HER and OER, respectively. The significantly low overpotential 104 mV for HER and 240 mV for OER at 10 mA/cm2 depicted the efficiency of catalyst. The chronoamperometry study showed no significant loss in the activity CTC coating upto 32 h. Thus, the CTC coated electrode is found to be an excellent, stable and robust electrocatalyst for economical green H2 production. [ABSTRACT FROM AUTHOR]

Supercapacitors and many other high-performance energy storage technologies have been the subject of intense research due to the rapidly growing interest in wearable electronics and electric cars. Self-assembled porous networks like nano-micro clusters of zinc cobaltite (ZnCo2O4, ZCO) have been synthesized using a simple, one-step and inexpensive reflux method for supercapacitor application. The effect of ionic surfactant (trisodium citrate, TSC) on the growth of the ZCO nanoparticles was studied. The structural, morphological, and electrochemical performance of the TSC-assisted ZCO electrodes were thoroughly tested. XRD studies reveal the spinel simple cubic (Fd3m) structure of ZCO clusters. RAMAN shows five active phonon (F2g, F2g, F2g, Eg, A1g) modes present in synthesized samples. BET provides a maximum 49.49 m2/g specific surface area for an optimistic sample. The porous structured TSC-assisted ZCO electrode enables electrochemical specific capacitance of 629 F/g (61.2 mAh/g) at a current density of 1 mA/cm2 with a specific energy of 38.55 Wh/kg and power delivery of 450 W/kg. Furthermore, to check the practical suitability of the electrode, cyclic stability was studied, showing retention of 84.20% specific capacitance after 5000 consecutive CV cycles at 50 mV/s. Hence, the results indicated that the cost-effective and eco-friendly method of preparing nano-micro clusters like binary transition metal oxides provides a new direction for future research. [ABSTRACT FROM AUTHOR]

An immensely selective sensor TiO2-ZnO-BMIMBr nanocomposite was developed as sensing materials for dopamine. ILs ([BMIM]+[Br]−) contribute as green dispersing media for the nanostructures, improving conductivity and biocompatibility. The surface morphologies, microstructure, and chemical compositions of the nanocomposite were probed by scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), RAMAN, X-ray diffraction (XRD) and Thermo gravimetric analysis (TGA-DTA). The electrochemical behaviours of DA at the bare and modified GCEs (TiO2, ZnO, TiO2-ZnO-BMIMBr) were investigated in acetate buffer solution (0.1 M, pH 7.4) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Compared with the bare electrode, TiO2-ZnO-BMIMBr/GCE shows the oxidation peak current (ipa) of increased magnitude, owing to the synergistic effect between TiO2 and ZnO in TiO2-ZnO-BMIMBr. The detection limit of the nanocomposite was found 4.09 μM by CV and 8.14 μM by DPV (S/N = 3). Moreover, the response peak current of DA is not interfered with the coexistence of ascorbic acid (AA), uric acid (UA), and glucose. TiO2-ZnO-BMIMBr has tremendous prospects for the detection of DA in urine samples. [ABSTRACT FROM AUTHOR]

Here we report a solvothermal–hydrothermal based method for the synthesis of spherical chromium oxide (Cr2O3) nanoparticles in 1-butyl-3-methyl imidazolium bromide ([BMIM]+[Br]−) and water (1:1 V/V) as a solvent. Electrochemical glucose sensing was performed by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The working electrode, glassy carbon electrode (GCE) was modified by using the synthesized Cr2O3 nanoparticles. The performance of the Cr2O3 nanoparticles modified GCE for glucose sensing is found to be highly sensitive with the limits of detection 1.47 × 10−4 M (LOD) and limits of quantification (LOQ) 4.91 × 10−4 M. The linear range of glucose detection is determined to be 2.78 × 10−4 M to 1.94 × 10−3 M. The sensitivity of the modified GCE for glucose is determined to be 2.25 × 10−2 A L mol−1 cm−2. From DPV, LOD corresponds to 1.08 × 10−4 M while the LOQ is determined at 3.60 × 10−4 M. The linear range of glucose detection by DPV is lower, 8.33 × 10−4 M to 1.94 × 10−3 M than that of CV. The glucose sensitivity also improves to 3.07 × 10−3 A L mol−1 cm−2 by DPV technique. Finally, the Cr2O3 nanoparticles modified GCE is used successfully to determine the glucose contents in human urine samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study shows a simplistic, efficient procedure to synthesize TiO 2 -MoO 3 -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 TiO 2 -MoO 3 -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., Competing Interests: All authors declares that there is no financial or any other authorship related conflict of interest amongst the authors., (This journal is © The Royal Society of Chemistry.)

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 ZnCo 2 O 4 nanorod arrays as ZnCo 2 O 4 @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 ZnCo 2 O 4 @NiO is used as an electrode material in a supercapacitor as it provides a high specific surface area (134.79 m 2 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 ZnCo 2 O 4 @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 ZnCo 2 O 4 @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 ZnCo 2 O 4 @NiO architecture electrode is a promising functional material for energy storage devices., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Nickel (Ni 2+ ) 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., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)