摘要：
A graphene oxide (GO) film coated glassy carbon electrode (GCE) was fabricated for sensitive determination of 4-nitrophenol (4-NP). The GO-based sensor was characterized by scanning electron microscope, atomic force microscopy and electrochemical impedance spectroscopy. The electrochemical behaviors of 4-NP at the GO-film coated GCE were investigated in detail. In 0.1 M acetate buffer with a pH of 4.8, 4-NP yields a very sensitive and well-defined reduction peak at the GO-modified GCE. It is found that the GO film exhibits obvious electrocatalytic activity toward the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. Various kinetic parameters such as transfer electron number, transfer proton number and standard heterogeneous rate constant were calculated, and various experimental parameters were also optimized. Under the optimal conditions, the reduction peak current varies linearly with the concentration of 4-NP ranging from 0.1 to 120 mu M, and the detection limit is 0.02 mu M at the signal noise ratio of 3. Moreover, the fabricated sensor presented high selectivity and long-term stability. This electrochemical sensor was further applied to determine 4-NP in real water samples, and it showed great promise for simple, sensitive, and quantitative detection of 4-NP. (C) 2011 Elsevier B.V. All rights reserved.
摘要：
A promising sensing platform for the ultrasensitive detection of dopamine (DA) has been constructed using MnO2 nanowires-electrochemically reduced graphene oxide modified glassy carbon electrode (MnO2 NWs-ErGO/GCE). The proposed MnO2 NWs-ErGO/GCEs had the large electrochemical active area and relative low charge transfer resistant (R-ct). As a result, the response peak current of the MnO2 NWs-ErGO is about 13 times higher than that of the bare GCE, demonstrating the remarkable electrocatalytic activity toward DA. The electrochemical kinetics revealed that DA oxidation is quasi-reversible reaction coupling with one electron and two protons. Three linear ranges (0.01 mu M - 0.10 mu M, 0.10 mu M - 1.0 mu M, and 1.0 mu M - 80 mu M) were obtained on the MnO2 NWs-ErGO/GCE, with a low detection limit of 1.0 nM (S/N = 3). Moreover, the response current was almost unaltered even in the presence of 100-fold ascorbic acid (AA) and uric acid (UA), suggesting MnO2 NWs-ErGO has good selectivity toward DA. Finally, the MnO2 NWs-ErGO/GCEs were successfully applied to detect DA in the injection solutions and human blood serum samples with high accuracy and good recovery. (C) 2018 Elsevier Ltd. All rights reserved.
摘要：
Amine-modified magnetite (NH(2)-Fe(3)O(4))/reduced graphene oxide nanocomposite modified glassy carbon electrodes (NH(2)-Fe(3)O(4)/RGO/GCEs) were developed for the sensitive detection of dopamine (DA). The NH(2)-Fe(3)O(4)/RGO/GCEs were fabricated using a drop-casting method followed by an electrochemical reduction process. The surface morphologies, microstructure and chemical compositions of the NH(2)-Fe(3)O(4) nanoparticles (NPs), reduced graphene oxide (RGO) sheets and NH(2)-Fe(3)O(4)/RGO nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The electrochemical behaviors of DA on the bare and modified GCEs were investigated in phosphate buffer solution (PBS) by cyclic voltammetry (CV). Compared with bare electrode and RGO/GCE, the oxidation peak current (ipa) on the NH(2)-Fe(3)O(4)/RGO/GCE increase significantly, owing to the synergistic effect between NH(2)-Fe(3)O(4) NPs and RGO sheets. The oxidation peak currents (ipa) increase linearly with the concentrations of DA in the range of 1 x 10(-8) mol/L - 1 x 10(-7) mol/L, 1 x 10(-7) mol/L - 1 x 10(-6) mol/L and 1 x 10(-6) mol/L - 1 x 10(-5) mol/L. The detection limit is (4.0 +/- 0.36) x10(-9) mol/L (S/N = 3). Moreover, the response peak currents of DA were hardly interfered with the coexistence of ascorbic acid (AA) and uric acid (UA). The proposed NH(2)-Fe(3)O(4)/RGO/GCE is successfully applied to the detection of dopamine hydrochloride injections with satisfactory results. Together with low cost, facile operation, good selectivity and high sensitivity, the NH(2)-Fe(3)O(4)/RGO/GCEs have tremendous prospects for the detection of DA in various real samples.
作者机构：
[He, Quanguo; Li, Guangli; Tian, Yaling; Wu, Yiyong; Liu, Jun] Hunan Univ Technol, Sch Life Sci & Chem, Zhuzhou 412007, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Hunan Prov Key Lab Funct Met Organ Cpds, Hengyang 421008, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Key Lab Funct Organometall Mat Hunan Prov Univ, Hengyang 421008, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[He, Quanguo; Deng, Peihong; Deng, PH; Chen, Dongchu] Foshan Univ, Sch Mat Sci & Energy Engn, Foshan 528000, Peoples R China.
通讯机构：
[Deng, Peihong] H;[Deng, PH; Chen, DC] F;Hengyang Normal Univ, Hunan Prov Key Lab Funct Met Organ Cpds, Hengyang 421008, Peoples R China.;Hengyang Normal Univ, Key Lab Funct Organometall Mat Hunan Prov Univ, Hengyang 421008, Peoples R China.;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
摘要：
A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe(3)O(4) nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH(2)-Fe(3)O(4) NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and electrochemical technique were used to characterize the modified electrode. The electrochemical behavior of rutin on the Fe(3)O(4) NPs-ErGO/GCE was studied in detail. The electrochemical response of rutin at this modified electrode was remarkably higher than that of the bare GCE or other modified GCE (GO/GCE, Fe(3)O(4) NPs-GO/GCE, and ErGO/GCE). Under the optimum determination conditions, Fe(3)O(4) NPs-ErGO/GCE provided rutin with a broader detection range of 6.0 nM(-)0.1 microM; 0.1(-)8.0 microM and 8.0(-)80 microM, a minimum detectable concentration of 4.0 nM was obtained after 210 s accumulation. This novel method was applied in determination of rutin in pharmaceutical tablets and urine samples with satisfactory results.
作者机构：
[He, Quanguo; Li, Guangli; Tian, Yaling; Wu, Yiyong; Liu, Jun] Hunan Univ Technol, Sch Life Sci & Chem, Zhuzhou 412007, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Key Lab Funct Met Organ Cpds Hunan Prov, Hengyang 421008, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Key Lab Funct Organometall Mat Hunan Prov Univ, Hengyang 421008, Peoples R China.;[He, Quanguo; Tian, Yaling; Deng, Peihong; Wu, Yiyong] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[He, Quanguo; Chen, Dongchu] Foshan Univ, Sch Mat Sci & Energy Engn, Foshan 528000, Peoples R China.
通讯机构：
[Deng, Peihong] H;[Chen, Dongchu] F;Hengyang Normal Univ, Key Lab Funct Met Organ Cpds Hunan Prov, Hengyang 421008, Peoples R China.;Hengyang Normal Univ, Key Lab Funct Organometall Mat Hunan Prov Univ, Hengyang 421008, Peoples R China.;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
摘要：
A tryptophan (Trp) molecularly imprinted electrochemical sensor was fabricated by drop-coating an imprinted chitosan film on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes (MIP-MWCNTs/GCE). The surface morphology and electrochemical properties of the MIP-MWCNTs/GCE were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. The electrochemical performance of the MIP-MWCNTs/GCE with Trp showed that the signal of the oxidation current of Trp obtained with MIP-MWCNTs/GCE was significantly enhanced relative to that of the uncovered GCE, indicating that the modified electrode can accelerate electron transfer and has strong selectivity for Trp. The experimental conditions were optimized in parallel, and under the optimal conditions, the MIP-MWCNTs/GCE showed a good linear relationship between the Trp oxidation peak current and Trp concentrations in the ranges of 2.0nM-0.2muM, 0.2muM-10muM and 10muM-100muM The limit of detection (LOD) was 1.0nM (S/N=3), and the modified electrode had good reproducibility and stability. Finally, the MIP-MWCNTs/GCE was successfully applied to the determination of Trp in the human serum samples.
摘要：
A nanohybrid composed of Ag@Cu2O heterogeneous nanocrystals supported on N-doped reduced graphene oxide (Ag@Cu2O/N-RGO) has been synthesized by a simple wet-chemical method. The resultant composite consists of N-RGO sheets fully and homogeneously coated with a dense layer of Ag@Cu2O nanocrystals. Both Ag and N-RGO are in direct contact with Cu2O, and Ag nanoparticles with sizes of 2-5 nm are mainly deposited on the surface of Cu2O cubes (edge length of 500 nm). The electrochemical studies reveal that the ternary Ag@Cu2O/N-RGO composite exhibit significantly enhanced electrocatalytic activity for H2O2 sensing compared with either the single component (N-RGO) or two component systems (Cu2O/N-RGO and Ag/N-RGO), which is mainly due to the synergetic catalysis of the ternary system. The nonenzymatic sensor based on Ag@Cu2O/N-RGO composite shows overwhelmingly superior comprehensive performance for the H2O2 detection over the documented Ag-based sensors. More specifically, it displays a rapid response (10 s) to H2O2 over a wide linear range of 54-700 nM with a high sensitivity of 1298.3 mu A mM(-1) cm(-2) and a low detection limit of 10 nM. Moreover, the sensor also exhibits the preferable selectivity in the presence of biologically coactive compounds accompanied with long-term stability and good reproducibility. (C) 2018 Elsevier B.V. All rights reserved.
期刊：
Sensors and Actuators B-Chemical,2012年168:381-389 ISSN：0925-4005
通讯作者：
Deng, Peihong
作者机构：
[Deng, Peihong; Xu, Zhifeng; Li, Junhua; Feng, Yonglan] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
通讯机构：
[Deng, Peihong] H;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
关键词：
p-Nitrophenol;Salicylaldehyde-modified chitosan;Acetylene black paste electrode;Voltammetric determination
摘要：
A novel method has been developed for the determination of p-nitrophenol (p-NP), which was based on the enhanced electrochemical response of p-NP at an acetylene black paste electrode coated with salicylaldehyde-modified chitosan (denoted as S-CHIT/ABPE). In 0.2 mol L−1 HCl solution, p-NP yielded a sensitive reduction peak at −0.348 V. Compared with the poor response at conventional carbon paste electrode, S-CHIT/ABPE remarkably increased the peak current of p-NP. All the experimental conditions, which influence the electrochemical response of p-NP, were studied and the optimum conditions were achieved. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range of 8.0 × 10−8 mol L−1 to 2.0 × 10−6 mol L−1 was developed for the determination of p-NP. The detection limit (S/N = 3) was also examined and a low value of 3.0 × 10−8 mol L−1 for 120 s accumulation was obtained. The method has been successfully applied to the determination of p-NP in water samples with good recovery in the range of 96–104%.
摘要：
Batch experiments were conducted to investigate the biosorption of U(VI) from aqueous solutions onto the nonliving biomass of an aquatic macrophyte Eichhornia crassipes. The results showed that the adsorption of U(VI) onto E. crassipes was highly pH-dependent and the best pH for U(VI) removal was 5.5. U(VI) adsorption proceeded rapidly with an equilibrium time of 30 min and conformed to pseudo-second-order kinetics. The Langmuir isotherm model was determined to best describe U(VI) biosorption with a maximum monolayer adsorption capacity of 142.85 mg/g. Thermodynamic calculation results indicated that the U(VI) biosorption process was spontaneous and endothermic. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis implied that the functional groups (amino, hydroxyl, and carboxyl) may be responsible for the U(VI) adsorption process, in which the coordination and ion exchange mechanisms could be involved. We conclude that E. crassipes biomass is a promising biosorbent for the removal of uranium pollutants.
