[Show abstract][Hide abstract] ABSTRACT: A green, sensitive and convenient electrochemical sensor was fabricated for the determination of Sudan I utilizing the excellent properties of poly(ionic liquids)-graphene nanocomposite. Compared with the glassy carbon electrode (GCE), the modified electrode significantly enhanced the oxidation peak current of Sudan I. This increase in electrochemical response was attributed to the positive charge of poly(ionic liquids) which facilitates the accumulation of Sudan I and the network structure of poly(ionic liquids) – graphene nanocomposite prepared by electrochemical reduction. Under optimized experimental conditions, the oxidation peak currents of Sudan I were linear to their concentrations in the range from 6.86×10-8 to 8.79×10-6 mol/L and the limit of detection of 2.3×10-8 mol/L was obtained. Finally, the proposed sensing method was successfully employed to detect Sudan I in food products such as chili powder and ketchup with satisfactory results.
[Show abstract][Hide abstract] ABSTRACT: Highly oriented, crystalline anatase TiO2 nanorod films with a  preferred growth direction were grown on transparent conducting substrates and characterized as photoanodes for water photoelectrolysis. The nanorods were grown by a simple hydrothermal reaction in a mixture of hydrochloric and sulfuric acids at 180 ° for 4 h. The phase and morphology of the crystalline TiO2 rods can be controlled by adjusting the concentration of H+ and the ratio of [Cl-] to [SO42-]. The high photocurrent for a photoanode of anatase TiO2 nanorods was correlated with rapid charge transfer determined from electrochemical impedance spectra. Rapid charge transport in crystalline anatase nanorod films should open new opportunities for applications, especially for heterojunction solar cells.
Chemistry of Materials 05/2015; 27(12):150527152041004. DOI:10.1021/acs.chemmater.5b00782 · 8.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Here, we demonstrate the fabrication of reduced graphene oxide films on different carbon-based substrates including glassy carbon electrode (GCE), graphite electrode, and carbon paste electrode through a green approach via direct electro-deposition technique. The resulting electrochemically reduced graphene oxide (ERGO) films have been investigated by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The as-prepared ERGO films modified electrodes show different and significant electrocatalytic activity toward nitrite oxidation. Among them, ERGO films modified GCE (ERGO/GCE) has been proven to function as electron transfer mediator and possess high electrocatalytic activity, stability and sensitivity, which might be attributed to the unique structural features of ERGO/GCE.
[Show abstract][Hide abstract] ABSTRACT: A novel electrochemical sensor for capsaicin using mesoporous cellular foams (MCFs) as sensitive material is reported. Surface morphology and electrochemical properties of the prepared MCFs modified carbon paste electrode (CPE) were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed modified electrode shows high sensitivity towards the oxidation of capsaicin in 0.1 M perchloric acid solutions (pH 1.0). Under optimized conditions, electrochemical oxidation currents of capsaicin were found to be linearly related to the concentration over the range 0.76 to 11.65 M with a correlation coefficient of 0.9990, and the detection limit was found to be 0.08 M at a signal-to-noise ratio of 3. The proposed electrochemical sensor was successfully applied to the determination of capsaicin by using standard adding method with satisfactory results.
[Show abstract][Hide abstract] ABSTRACT: In this study, an electrochemical sensor of nitro aromatic compound based on three-dimensional porous Pt–Pd nanoparticles (Pt–Pd NPs) supported by reduced graphene oxide (rGO) nanosheets–multiwalled carbon nanotube (CNTs) nanocomposite (marked as Pt–Pd NPs/CNTs–rGO) was investigated for the first time. This hybrid nanocomposite has been prepared via a facile and versatile hydrothermal synthetic strategy while its structure and property are evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). The result shows that 3D porous Pt–Pd NPs/CNTs–rGO nanocomposite has a large specific surface area of 326.6 m2 g−1 and exhibited ultrahigh rate capability and good cycling properties at high rates. Electrochemical studies have been performed for the nitro aromatic compounds detection by using different pulse voltammetry (DPV) techniques. The proposed nanocomposite exhibited much enhanced elctrocatalytic activity and high sensitivity toward the detection of nitro aromatic compounds which compared with Pt–Pd NPs dispersed on functionalized rGO, Pt–Pd NPs dispersed on functionalized CNTs, rGO–CNTs and bare glass carbon electrode (GCE). On the basis of the above synergetic electrochemical sensing and synthesis procedure, the hybrid material can be recommended as a robust material for sensor-related applications. Moreover, the proposed sensor exhibits high reproducibility, long-time storage stability and satisfactory anti-interference ability.
[Show abstract][Hide abstract] ABSTRACT: Firstly, polyethyleneimine (PEI) functionalized multiwalled carbon nanotubes (MWNTs) were used as growth scaffold on a glass carbon electrode (GCE). Then, Au nanoparticles were uniformly electrodeposited as seeds. Finally, Pt nanoparticles (PtNPs) grew on Au PtNPs to form Pt@Au core-shell structure nanocomposite. A new type of electrochemical sensor based on Pt@Au/PEI-MWNTs nanocomposites for detection of hydrogen peroxide was then developed with the wide linear range from 9.2 × 10−8 M to 1.3 × 10−3 M.
Chinese Journal of Analytical Chemistry 06/2014; 42(6):835–841. DOI:10.1016/S1872-2040(14)60744-1 · 0.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The multi-dimension network of sol-gel SiO2 was immobilized on an electrode surface employing sol-gel and electrochemical impedance spectroscopy (EIS) techniques under the optimal experimental conditions. Then, the multi-dimension network structure of sol-gel was used to simulate electron transfer in cell membrane of micro interface. The electron transfer model was constructed successfully on the multi-dimension micro interface. These SiO2 materials exhibited tunable porosity, high thermal stability and chemical inertness.
Chinese Journal of Analytical Chemistry 08/2013; 41(8):1249–1253. DOI:10.1016/S1872-2040(13)60674-X · 0.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, coenzyme Q10 (Ubiquinone, CoQ10) was used for the first time as a transducer to construct electrochemical biosensor for effectively detecting γ-l-glutamyl-l-cysteinyl-glycine (glutathione, GSH). CoQ10 modified electrode was fabricated by attaching its gel mixed with multi-walled carbon nanotubes (MWNTs)/ionic liquid (IL). In the optimum conditions, based on the increasing of reduction peak current of CoQ10 caused by GSH through voltammetric technology, it was found that the peak current of CoQ10 was linear with the concentration of GSH in the range from 4.0×10(-9) to 2.0×10(-7)molL(-1) at the pH 7.00, and the limit of detection was 3.2×10(-10)molL(-1) (S/N=3). The results revealed that this method could be used to determine GSH in actual blood samples with the superiority of excellent selectivity, high stability and sensitivity. The strategy explored here might provide a new pathway to design novel multi-function transducers for detecting GSH, which has unique characteristic and potential application in the fields of sensor and medical diagnosis.
[Show abstract][Hide abstract] ABSTRACT: The title compound, C(28)H(38)Br(2)N(2), is centrosymmetric with the mid-point of the central C-C bond of the butyl group located on an inversion center. The terminal benzene ring is approximately perpendicular to the central 1,4-diaza-butadiene mean plane [dihedral angle = 78.23 (3)°]. No hydrogen bonding or aromatic stacking is observed in the crystal structure.
[Show abstract][Hide abstract] ABSTRACT: A novel mesoporous-coated stainless steel wire microextraction coupled with the HPLC procedure for quantification of four polycyclic aromatic hydrocarbons in water has been developed, based on the sorption of target analytes on a selectively adsorptive fiber and subsequent desorption of analytes directly into HPLC. Phenyl-functionalized mesoporous materials (Ph-SBA-15) were synthesized and coated on the surfaces of a stainless steel wire. Due to the high porosity and large surface area of the Ph-SBA-15, high extraction efficiency is expected. The influence of various parameters on polycyclic aromatic hydrocarbons extraction efficiency were thoroughly studied and optimized (such as the extraction temperature, the extraction time, the desorption time, the stirring rate and the ionic strength of samples). The results showed that each compound for the analysis of real water samples was tested under optimal conditions with the linearity ranging from 1.02×10(-3) to 200 μg/ L and the detection limits were found from 0.32 to 2.44 ng/ L, respectively. The RSD of the new method was smaller than 4.10%.
[Show abstract][Hide abstract] ABSTRACT: Dual fluorescence and UV absorption of 2'-ethylhexyl 4-(N,N-dimethylamino)benzoate (EHDMAB) were investigated in cationic, non-ionic and anionic micelles. When EHDMAB was solubilized in different micelles, the UV absorption of EHDMAB was enhanced. Twisted intramolecular charge transfer (TICT) emission with longer wavelength was observed in ionic micelles, whereas TICT emission with shorter wavelength was obtained in non-ionic micelles. In particular, dual fluorescence of EHDMAB was significantly quenched by the positively charged pyridinium ions arranged in the Stern layer of cationic micelles. UV radiation absorbed mainly decays via TICT emission and radiationless deactivation. The dimethylamino group of EHDMAB experiences different polar environments in ionic and non-ionic micelles according to the polarity dependence of TICT emission of EHDMAB in organic solvents. In terms of the molecular structures and sizes of EHDMAB and surfactants, each individual EHDMAB molecule should be buried in micelles with its dimethylamino group toward the polar head groups of different micelles and with its 2'-ethylhexyl chain toward the hydrophobic micellar core. Dynamic fluorescence quenching measurements of EHDMAB provide further support for the location of EHDMAB in different micelles.
Chinese journal of chemical physics 04/2008; 21(2):163-168. DOI:10.1088/1674-0068/21/02/163-168 · 0.50 Impact Factor