•PBG/CQDs/GCE has been successfully fabricated by electropolymerization.•PBG/CQDs/GCE showed excellent electrocatalysis towards guanine and adenine.•PBG/CQDs/GCE exhibited prominent selectivity, stability and reproducibility.A novel poly(bromocresol green) (PBG)/carbon quantum dots (CQDs) composite based sensor was successfully fabricated on glassy carbon electrode by electropolymerization. As-prepared PBG/CQDs modified electrode was successfully applied in the simultaneous determination of guanine and adenine. Electrochemical responses of as-prepared modified electrode were evaluated by cyclic voltammetry and differential pulse voltammetry. Owing to the synergistic effect of PBG and CQDs, the oxidation peaks of both guanine and adenine well separated from each other and the peak potential separation was large up to 310 mV. The current of the oxidation peaks showed a linear dependence on the concentrations of guanine and adenine in the range of 0.50–142 and 0.30–130 μM with detection limits of 0.016 and 0.026 μM (S/N = 3), respectively. Moreover, as-prepared PBG/CQDs modified electrode exhibited favorable selectivity, stability and reproducibility, which had promising application for the simultaneous determination of guanine and adenine.Shown up were preparation procedure and application of as-prepared electrode. Shown down were DPVs of the simultaneous determinations of guanine and adenine in 0.10 M HAc-NaAc buffer (pH 4.7) on PBG/CQDs/GCE.Download high-res image (145KB)Download full-size image

In this work, oxygen-rich activated carbon compounds were prepared from three kinds of biomass by simple carbonization and they were investigated as electrodes for supercapacitors. The selected biomasses were waste dragon fruit skin, Momordica grosvenori skin and Firmiana catkins. Three kinds of as-prepared activated carbons showed abundant oxygen-containing groups and typical amorphous characteristics with high specific surface areas of 911.2 m2 g−1, 597.5 m2 g−1 and 286.7 m2 g−1, respectively. This combination of high specific surface areas and abundant active surface functional groups resulted in capacitances of 286.9 F g−1, 238.7 F g−1 and 226.6 F g−1 at 0.5 A g−1, respectively. Furthermore, three kinds of as-prepared activated carbons also showed excellent cycling performance with nearly 100% retention over 5000 cycles at 4.0 A g−1 in 2.0 mol l−1 KOH solution. As a result, three kinds of as-prepared activated carbons exhibited favorable electrochemical performances in potential application as electrode materials for supercapacitors.

•Novel MoS2 nanosheets–decorated PANI was synthesized.•Aggregation of MoS2 nanosheets were prevented by homogeneously distributing on PANI.•PANI was used as conductive substrate to promote electron transport of composite.•The composite exhibited higher electrocatalytic activity for HER than pure MoS2.•The composite with 19 wt% PANI showed current density of 80 mA cm−2 at 400 mV.Novel molybdenum disulfide nanosheets–decorated polyaniline (MoS2/PANI) was synthesized and investigated as an efficient catalyst for hydrogen evolution reaction (HER). Compared with MoS2, MoS2/PANI nanocomposites exhibited higher catalytic activity and lower Tafel slope for HER in H2SO4 solution. The amount of 19 wt% PANI for coupling with MoS2 resulted in a high current density of 80 mA cm−2 at 400 mV (vs. RHE). In addition, the optimal MoS2/PANI nanocomposite showed impressive long-term stability even after 500 cycles. The enhanced catalytic activity of MoS2/PANI nanocomposites was primarily ascribed to the effective electron transport channels of PANI and the increase of electrochemically accessible surface area in composite materials, which was advantageous to facilitate the charge transfer at catalyst/electrolyte interface.Shown in left was the morphology of MoS2/PANI-5 sample. As we can see, MoS2 nanosheets were homogeneously dispersed on the surface of PANI and tended to exist in the form of smaller nanosheets. Shown in right were the steady-state polarization curves of MoS2/PANI-3, MoS2/PANI-4, MoS2/PANI-5, MoS2/PANI-7 and Pt electrodes in 0.50 M H2SO4 solution at 293 K. It was observed that MoS2/PANI-5 electrode presented the optimized cathodic current density at the same potential.

The authors describe a composite material prepared from carbon nanohorns and poly(2-aminopyridine) that was obtained by electrochemical polymerization of 2-aminopyridine on carbon nanohorns. The material was used to modify a glassy carbon electrode (GCE) to obtain a sensor for non-enzymatic determination of hydrogen peroxide. The modified GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The modified electrode is shown to display excellent electrical conductivity and catalytic activity towards hydrogen peroxide, mainly due to the large specific surface area of carbon nanohorns, the good electron charge transfer properties resulting from the use of poly(2-aminopyridine), and their synergistic effect. The response of the modified GCE (best operated at a working potential of −0.45 V vs. SCE) to H2O2 is linear in the 0.05 to 8 mM concentration range. The limits of detection (LOD) and quantitation (LOQ) are 3.6 μM and 12.4 μM, respectively. The electrode is selective, stable and reproducible, this making it a promising tool for non-enzymatic determination of hydrogen peroxide.

A novel cuprous oxide-attapulgite/graphene based non-enzyme biosensor was constructed successfully for the detection of glucose. Graphite oxide and Cu2+-functionalized attapulgite were simultaneously reduced by hydrazine hydrate under mild hydrothermal conditions in one pot, and subsequently dried at 80 °C in air to obtain cuprous oxide-attapulgite/graphene composites. The composites were characterized by XRD, Raman spectroscopy, EDX and SEM. Due to the synergistic effect of cuprous oxide-attapulgite and graphene, the as-prepared composites presented excellent electrocatalytic performances. The cuprous oxide-attapulgite/graphene modified electrode exhibited sensitive linear amperometric responses to glucose in the concentration range of 4.0 × 10−5 M to 3.0 × 10−3 M (R = 0.996), and the detection limit was calculated to be 2.1 × 10−6 M. The as-prepared modified electrode was highly selective for glucose in the presence of common interfering species in biological fluids, such as dopamine, ascorbic acid and uric acid.

•Triple-phase interface synthesis of nanostructured composites was firstly proposed.•One-step route for the preparation of core–shell PPy/PANI composite was achieved.•As prepared PPy/PANI composite showed superior capacitance behaviors.We first present an alternative one-step route for constructing a novel polyaniline (PANI)-coated polypyrrole (PPy) composite in an ingenious triple-phase interface system, where PPy and PANI are prepared in individual non-interference interfaces and, in the middle aqueous phase, smaller PANI particles are uniformly coated on the surface of PPy particles, forming a core–shell structure. The prepared PPy/PANI composite electrode shows a superior capacitance behavior that is more suitable for supercapacitor application.Shown above were schematic illustration of interfacial synthesis of PPy/PANI composite and SEM images of PPy (a), PANI (b) and PPy/PANI composite (c).

•An aqueous/organic interface reaction with soft template was employed in this paper.•Novel ultralong interconnected PPy nanowire was prepared.•Hybrid structured (nanowires & nanoparticles) PPy presented better capacitance behavior.In this paper, novel ultralong interconnected polypyrrole (PPy) nanowires were synthesized by an interfacial reaction of pyrrole in organic phase and ammonium persulfate in aqueous phase using cetyltrimethylammonium bromide (CTAB) as soft template. The morphology of as prepared PPy was investigated by field emission scanning electron microscopy and transmission electron microscopy. The electrochemical performance of as prepared PPy was evaluated as electrode materials for electrochemical capacitor by the means of cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was shown that the size and morphology of as prepared PPy can be optionally controlled by varying the concentration of CTAB in aqueous phase, and CTAB concentration played a crucial role in improving the electrochemical performances of as prepared PPy nanowire at high charge/discharge rate. In the presence of 6.25 ∼ 12.5 mM CTAB, ultralong interconnected PPy nanowire bonded with spherical PPy nanoparticles can be perfectly prepared. The diameter of PPy nanowire was in the range of 20 to 100 nm with length up to about several micrometers. A higher specific capacitance was obtained up to 328.7 F g−1 at current density of 0.3 A g−1. 75.7% of initial capacitance was retained even after 600 cycles at current density of 1.0 A g−1.

Microspherical shaped cobalt–manganese oxide (CMO) as electrode materials for supercapacitor is synthesized by solvothermal method. The microstructure and surface morphology of CMO are characterized by X-ray diffraction and scanning electron microscopy, respectively. Cyclic voltammetry and chronopotentiometry are employed for the characteristics of electrode process and the calculation of specific capacitance in KOH solution. It is shown that as prepared CMO with cobalt/manganese mole ratio of 1:2 has excellent specific capacitance of 348.0 F g−1 at current density of 0.5 A g−1. In addition, long-term stability of the composites electrode is measured at current density of 1.0 A g−1, and 58.6% of initial capacitance is retained after 500 cycles.

•Attapulgite was used as a template to control size and morphology of polyaniline.•Phosphomolybdic acid was stably anchored on attapulgite/PANI composite.•Attapulgite/PANI/PMo12/GCE showed perfect electrocatalytic activity to iodate.•Detection limit of attapulgite/PANI/PMo12/GCE for iodate was found to be 0.53 μM.A novel attapulgite/polyaniline/phosphomolybdic acid-based amperometric sensing platform was constructed for the determination of iodate. Nanostructured attapulgite was utilized for reducing agglomeration of polyaniline particles, and the as prepared attapulgite/polyaniline composite was used to immobilize phosphomolybdic acid. Excellent electrocatalytic performance was obtained due to the synergistic effect of nanostructured attapulgite, polyaniline and phosphomolybdic acid. The electrochemical responses of as prepared modified electrode were investigated by cyclic voltammetry and chronoamperometry. The modified electrode exhibited linear amperometric response for iodate in the concentration range of 2.0 × 10−6 M–5.2 × 10−4 M (R = 0.999). The detection limit was calculated as 5.3 × 10−7 M. Good reproducibility, high stability, fast amperometric response, and possibility of rapid preparation were also great advantages of this modified electrode. Based on this work, the attapulgite/polyaniline/phosphomolybdic acid modified electrode was successfully applied to determine iodate in a commercial table salt sample.Graphical abstractShown in left were CVs on attapulgite/PANI/PMo12/GCE at different scan rates in the range of 10–500 mV/s in 0.50 M H2SO4 + 0.50 M Na2SO4 solution. Shown in right was current–time plot of iodate with increasing concentrations on attapulgite/PANI/PMo12/GCE in 0.50 M H2SO4 + 0.50 M Na2SO4 solution.

•Organophilic vermiculite was prepared by ionic exchange reaction.•Composite gel polymer electrolytes (CGPEs) were prepared by solution cast method.•The introduction of organophilic vermiculite decreased the crystallinity of CGPE.•Organophilic vermiculite contributed to an increase of ionic conductivity of CGPE.•The electrochemical window of CGPE reached up to 3.8 V.Organophilic vermiculite was prepared by ionic exchange reaction between vermiculite and cetyltrimethylammonium bromide, and it was then used as filler to prepare a series of composite gel polymer electrolytes containing poly(methyl methacrylate) and room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. Surface morphology and structural nature of the composite electrolytes were examined by scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. X-ray diffraction analysis confirmed that organophilic vermiculite decreased the crystallinity of polymer and formed intercalated polymer/layered silicate composite. On the other hand, the dispersion of organophilic vermiculite increased the thermal property of polymer electrolytes. Furthermore, the ionic conductivity and electrochemical window of composite gel polymer electrolyte reached up to the value of 4.01 × 10−3 S cm−1 and 3.8 V at the adding content of 8 wt.% organophilic vermiculite, respectively.

A novel bacterial cellulose nanofiber-based carbon paste electrode (BCPE) was fabricated. It was characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Compared with traditional carbon paste electrode, BCPE exhibited better electrochemical reversibility with the enhancement of the redox currents and decrease of peak potential separation as well as lower charge transfer resistance in Fe(CN)63−/4− redox system. Keggin-type sodium phosphopolyoxomolybdate, PMo12, was successfully assembled on BCPE via cyclic voltametric scan, and the obtained PMo12/BCPE possessed not only a good electrochemical behavior but also an excellent electrocatalytic activity toward the reduction of nitrite. Because of its nano-dimension, lower cost and prominent electrochemical properties, bacterial cellulose-based carbonaceous materials would be a candidate of graphite for the preparation of novel carbon paste electrode.