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Herein, three-dimensional reduced graphene oxide/helical carbon nanotubes (RGO/HCNTs) nanocomposites were synthesized by a combined solution-based method and chemical vapor deposition. This synergistic structure of graphene and helical carbon nanotube exhibited large flexibility, rapid transport kinetics, and excellent electrochemical characteristic. The hemoglobin (Hb) was immobilized on the surface of the RGO/HCNTs nanocomposites for amperometric sensing of HO. The dependence of the electrochemical performance of Hb on the composition of RGO/HCNTs composites is systematically investigated by varying the weight ratio of reduced RGO/HCNTs. Compared with alone graphene or HCNTs electrodes modified with Hb, the catalytic current for HO reduction at the Hb-modified RGO/HCNTs electrode increased due to the increase in the surface coverage of Hb and the excellent electrocatalytic activity of RGO/HCNTs. The constructed biosensor displayed a fast electron transfer of Hb and an excellent electrochemical activity for the detection of HO with high selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

Recently, Pt-Y alloy has displayed an excellent electrocatalytic activity for oxygen reduction reaction (ORR), and is regarded as a promising cathode catalyst for fuel cells. However, the bulk production of nanoscaled Pt-Y alloy with outstanding catalytic performance remains a great challenge. Here, we address the challenge through a simple dealloying method to synthesize nanoporous Pt-Y alloy (NP-PtY) with a typical ligament size of ~5 nm. By combining the intrinsic superior electrocatalytic activity of Pt-Y alloy with the special nanoporous structure, the NP-PtY bimetallic catalyst presents higher activity for ORR and ethanol oxidation reaction, and better electrocatalytic stability than the commercial Pt/C catalyst and nanoporous Pt alloy. The as-made NP-PtY holds great application potential as a promising electrocatalyst in proton exchange membrane fuel cells due to the advantages of facile preparation and excellent catalytic performance. [ABSTRACT FROM AUTHOR]

The key step in the fabrication of highly active electrochemical sensors is seeking multifunctional nanocomposites as electrode modified materials. In this study, the gold nanoparticle-decorated helical carbon nanotube nanocomposites (AuNPs-HCNTs) were fabricated for rutin detection because of its superior sensitivity, the chemical stability of AuNPs, and the superior conductivity and unique 3D-helical structure of helical carbon nanotubes. Results showed the prepared nanocomposites exhibited superior electrocatalytic activity towards rutin due to the synergetic effects of AuNPs and HCNTs. Under the optimized conditions, the developed sensor exhibited a linear response range from 0.1 to 31 μmol/L for rutin with a low detectable limit of 81 nmol/L. The proposed method might offer a possibility for electrochemical analysis of rutin in Chinese medical analysis or serum monitoring owing to its low cost, simplicity, high sensitivity, good stability, and few interferences against common coexisting ions in real samples. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (N-CNTs)/gold composites were synthesized through a simple self-assembly method. The morphology, composition, and optical properties of the resulted composites were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, ultraviolet-visible absorption spectrum, and X-ray photoelectron spectroscopic. This nanocomposite combines the advantages of N-CNTs and gold nanoparticales showing many excellent properties such as good dispersibility in water and satisfactory biocompatibility. Cyclic voltammogram experiment shows that N-CNTs/gold composite has high conductivity. Based on these aspects, N-CNTs/gold-modified electrode was applied to the voltammetric determination of thioridazine hydrochloride (TH) successfully. The linear calibration range for the TH sensor was 12 ~ 850 μM with a detection limit of 1.3 μM at a signal-to-noise ratio of 3, long-term stability, and good reproducibility. [ABSTRACT FROM AUTHOR]

Three-dimensional nanoporous PtSi (NP-PtSi) alloy was prepared by dealloying ternary PtSiAl alloy ribbons. By combining the nanoporous morphology of PtSi and graphene (GR), a new composite material was developed, which was used to modify the surface of a glassy carbon electrode (GCE). The resulting modified electrodes showed an excellent electrocatalytic activity towards the electro oxidation of bisphenol A. Based on differential pulse voltammetry measurements, NP-PtSi/GR/GCE showed linear response over the concentration range 0.30 to 85 μM bisphenol A, while the detection limit was found to be 0.11 μM (S/N = 3). NP-PtSi/GR/GCE showed also satisfactory stability and selectivity over various compounds present in real samples, and they were successfully applied to the determination of bisphenol A in inoculated milk samples. [ABSTRACT FROM AUTHOR]

Three-dimensional nanoporous copper (NPC) was fabricated by dealloying ribbons of an Al-Cu alloy. NPC possesses a clean metal surface and high electrical conductivity. Subsequently, a non-enzymatic electrochemical sensor was obtained by modifying a glassy carbon electrode with nanocomposites containing nanoporous copper and carbon black (NPC-CB) in a nafion matrix. The sensor, if operated at a working voltage of 0.6 V (vs. SCE) in 50 mM NaOH solution, has a linear analytical range that extends from 6.0 μM to 3.4 mM of glucose, and a 2.6 μM detection limit (at an S/N ratio of 3). It also shows good selectivity over ascorbic acid, uric acid, dopamine and carbohydrates (fructose, saccharose, and maltose). The sensor also has a rapid amperometric response to hydrogen peroxide which can be quantified with a 1.2 μM detection limit. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A nanocomposite consisting of helical carbon nanotubes, polyallylamine hydrochloride and CdSe quantum dots was synthesized and used for the electrochemiluminescent determination of dopamine in presence of peroxodisulfate. The nanocomposite was characterized by transmission electron microscopy, UV-absorption and photoluminescence spectroscopy. The electrochemical process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the ECL intensity decreases linearly with the concentration of dopamine in the 1.0 × 10 mol · L to 2.0 × 10 mol · L range, with a 0.2 × 10 mol · L detection limit. The method represents a rapid, simple and sensitive protocol for the determination of dopamine. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]