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Zhang J.,Soochow University of China | Zhu Z.,Soochow University of China | Di J.,Soochow University of China | Long Y.,Soochow University of China | And 3 more authors.
Electrochimica Acta | Year: 2015

This work reports a sensitive sensor for the electrochemical determination of trace mercury (Hg2+) by employing ultrathin graphitic carbon nitride (utg-C3N4) nanosheet as enhanced sensing platform. The utg-C3N4 nanosheets were obtained by exfoliating the bulk g-C3N4, which was synthesized via a thermal polycondensation process. The as-prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM), which confirmed graphite-like structure with thickness of about 8 nm. The g-C3N4 nanosheets can be easily attached on the surface of glassy carbon (GC) electrode free of any film-forming agent. It was found that Utg-C3N4 modified GC electrode showed enhanced electrochemical response to Hg2+ in comparison with bulk g-C3N4, which could be ascribed to the strong affinity between utg-C3N4 and Hg2+ through its -NH and -NH2 groups. This allows detection of Hg2+ in aqueous solutions with high sensitivity and selectivity. Under the optimized experimental conditions, the anodic stripping voltammetric (ASV) currents are linearly responsible to Hg2+ concentrations in the range of 0.1-15 μg/L with a detection limit of 0.023 μg/L (S/N = 3). The sensitivity of the as-constructed sensor is about 6.8 μA(μg/L)-1 cm-2. In addition, the proposed sensor was applied in determining Hg2+ in practical samples and the results are comparable to those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) method. © 2015 Elsevier Ltd. Source

Changbin X.,Soochow University of China | Qun Z.,Soochow University of China | Qun Z.,Nantong University | Yifeng T.,Soochow University of China | Yifeng T.,Key Laboratory of Health Chemistry and Molecular Diagnosis of Suzhou
Electrochimica Acta | Year: 2014

In this paper, we will describe an original approach to develop an all-solid-state electrochemiluminescent (ECL) electrode for reagentless detection. It was constructed based on the immobilization of poly(luminol/aniline) nano-rods, which was synthesized in aqueous medium by a simple one-pot strategy. The properties of the copolymer were characterized by microscopic, electrochemical and spectrometric investigations. It was then immobilized onto the surface of indium tin oxide coated glass to act as a working electrode for ECL analysis with the flow-injection mode. The as-prepared ECL electrode exhibited strong and stable ECL background in alkaline aqueous solution and responded toward some oxidants or antioxidants such as H2O2 (to be found to enhance its ECL) or resveratrol (to be found to quench its ECL). On this basis, the built reagentless ECL flow-injection analytical system was successfully applied to evaluate the gross antioxidant activity of some fruits with satisfactory results. © 2014 Elsevier Ltd. Source

Zhao Q.,Soochow University of China | Zhao Q.,Nantong University | Xiao C.,Soochow University of China | Tu Y.,Soochow University of China | Tu Y.,Key Laboratory of Health Chemistry and Molecular Diagnosis of Suzhou
Talanta | Year: 2015

The titania nanotubes (TiNTs) had been immobilised onto the indium tin oxide (ITO) coated glass to intensify the electrochemiluminescence (ECL) of luminol. The morphology, structure and properties such as specific surface area and transmittance of synthesised TiNTs were characterised. The results indicated that the TiNTs was several hundred nanometres in length with the diameter of 20 nm. In flow injection analysis (FIA) mode, the TiNTs dramatically enhanced the ECL emission of luminol for about 25 multiple, meanwhile decreased the requirement of buffer pH and exciting potential. The ECL emission of luminol on functionalised ITO electrode has sensitive response toward hydrogen peroxide, and extraordinarily responsive toward the antioxidant. Under the optimal conditions, the ECL emission exhibited a linear response within the concentration range from 0.1 mg L-1 to 30 mg L-1 and an absolute detection limit of 1.65×10-10 g of resveratrol. The gross antioxidant activity of blueberry and kiwi were determined with satisfactory recoveries. © 2015 Elsevier B.V. All rights reserved. Source

Yao S.,Soochow University of China | Zhang M.,Soochow University of China | Di J.,Soochow University of China | Wang Z.,Soochow University of China | And 3 more authors.
Applied Surface Science | Year: 2015

In this work, a novel α-SnWO4/SnO2 heterostructure was synthesized via a facile two-step hydrothermal method. The as-prepared products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scan electron microscopy (SEM) and transmission electron microscopy (TEM), which confirmed the typical orthorhombic α-SnWO4 phase, plate-like morphology and α-SnWO4/SnO2 heterostructure. The photocatalytic studies revealed that the attachment of SnO2 nanoparticles on the surface of α-SnWO4 plates can remarkably improve their photocatalytic activities and the α-SnWO4/SnO2 heterostructure exhibited the best photocatalytic properties in the degradation of methyl orange (MO) under visible light irradiation. The degradation rate of MO on α-SnWO4/SnO2 plate was 97% within 40 min and the photocatalytic degradation reaction followed the pseudo-first-order kinetics. The enhanced photocatalytic property was ascribed to the large surface area and the heterojuction between α-SnWO4 and SnO2, which can facilitate efficient charge separation of photogenerated electron-hole pairs. Furthermore, α-SnWO4/SnO2 nanocomposite demonstrated good recyclability, which is useful for its practical application. © 2015 Elsevier B.V. All rights reserved. Source

Dai X.,Soochow University of China | Qiu F.,Jilin University | Zhou X.,Soochow University of China | Long Y.,Soochow University of China | And 4 more authors.
Electrochimica Acta | Year: 2014

In this work, a new strategy for the simultaneous determination of Pb2+and Cd2+was described based on amino-functionalized mesoporous silica (NH2-MCM-41) as sensing mediator. NH2-MCM-41 was prepared using a post-grafting process and the successful amino-functionality was confirmed by Fourier transform infrared (FTIR) and X-ray energy dispersive (EDS) spectra. It was found that both MCM-41- and NH2-MCM-41-modified glassy carbon (GC) electrode exhibit simultaneous response to Pb2+and Cd2+. However, the NH2-MCM-41 modified electrode showed higher sensitivity than that of the MCM-41-modified one, which was attributed to the good chelating ability of amino groups to metal ions besides the high surface area and special mesoporous morphology of MCM-41. As a result, simultaneous assay of Pb2+and Cd2+was realized using anodic stripping voltammetric (ASV) method. Under the optimum experimental conditions, the linear response ranges for Pb2+and Cd2+ions are 0.5-250 μgL-1and 50-450 μgL-1, respectively. The corresponding detection limits are 0.2 μgL-1for Pb2+and 1.0 μgL-1for Cd2+, with good electrode renewability, which is defined as the complete removal of the accumulated metals from the electrode surface. In addition, the NH2-MCM-41 modified electrode was demonstrated for the successful determination of Pb2+and Cd2+in real samples, including tap water, lake water and tea. © 2014 Elsevier Ltd. All rights reserved. Source

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