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：
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.
