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Li M.,Xian University of Architecture and Technology | Dong S.,Xian University of Architecture and Technology | Li N.,Xian Chuanglian Huate Surface Treatment Technology Co. | Tang H.,Northwest University, China | Zheng J.,Northwest University, China
RSC Advances | Year: 2015

Synthesized magnetic ferroferric oxide carbon aerogel (Fe3O4-CA) was characterized by scanning electron microscope (SEM), atomic force microscopy (AFM) and N2 adsorption-desorption isotherm measurements. Subsequently, the Fe3O4-CA was mixed with ionic liquid (IL) to form a stable composite film, which was characterized by atomic force microscopy (AFM) and used as an electrochemical interface for accelerating electrochemistry of glucose oxidase (GOx) and myoglobin (Mb). The results demonstrated that direct electron transfer of GOx and Mb, respectively, was realized on the surface of Fe3O4-CA/IL with a pair of well-defined quasi-reversible redox peaks. The heterogeneous electron transfer rate constant (ks) and the surface coverage (Γ∗) were calculated as 1.30 s-1 and 4.10 × 10-10 M cm-2 for Fe3O4-CA/IL/GOx-CPE, 0.92 s-1 and 2.02 × 10-9 M cm-2 for Fe3O4-CA/IL/Mb-CPE, respectively. Moreover, the immobilized Mb exhibited excellent bioelectrocatalytic activity toward the reduction of hydrogen peroxide (H2O2). The biosensor displayed broad linear response to H2O2 in the range from 10 μM to 1450 μM with a detection limit of 3.2 μM. The results demonstrated that Fe3O4-CA/IL composite films could be a potential biocompatible interface owing to their excellent electron transfer activities, abundant mesoporous structures and large specific surface area, and wide potential applications may be developed in biosensors and biocatalysis. © The Royal Society of Chemistry 2015.


Zhang Y.,Northwest University, China | Zhou J.,Xian Chuanglian Huate Surface Treatment Technology Co. | Han X.,Northwest University, China | Zhang X.,Northwest University, China | Hu J.,Northwest University, China
Applied Surface Science | Year: 2015

The adsorption of n-Alkanethiols (CH3(CH2)n-1SH) self-Assembled monolayers on copper surface was investigated by electrochemical impedance spectroscopy. The variation of surface coverage versus time was obtained by charge transfer resistances and interfacial capacitance in the impedance. It was found that the adsorption process was consistent with Langmuir kinetics model, no matter changes in chain length and concentration of thiols. Based on the established model, the different adsorption and desorption rate constants were calculated to describe the adsorption process on copper surface. Furthermore, the variation of ka was revised when the concentration of thiols in solution was changed. According to our model and revised ka, the effects are explained on the basis of the diffusion and interaction between thiols and solvent in the formation of thiols SAMS on copper surface. © 2015 Elsevier B.V. All rights reserved.


Zhang Y.,Northwest University, China | Zhou J.,Xian Chuanglian Huate Surface Treatment Technology Co. | Zhang X.,Northwest University, China | Hu J.,Northwest University, China | Gao H.,Northwest University, China
Applied Surface Science | Year: 2014

This article reports the effect of solvent polarity on the formation of n-octadecanethiol self-assembled monolayers (C18SH-SAMs) on pure copper surface and oxidized copper surface. The quality of SAMs prepared in different solvents (n-hexane, toluene, trichloroethylene, chloroform, acetone, acetonitrile, ethanol) was monitored by EIS, RAIRS and XPS. The results indicated that C18SH-SAMs formed in these solvents were in good barrier properties on pure copper surface and the structures of monolayers formed in high polarity solvents were more compact and orderly than that formed in low polarity solvents. For comparison, C18SH adsorbed on the surface of oxidized copper in these solvents were studied and the results indicated that C18SH could be adsorbed on oxidized copper surface after the reduction of copper oxide layer by thiols. Compared with high polarity solvents, a limited reduction process of oxidized copper by thiols led to the incompletely formation of monolayers in low polarity solvents. This can be interpreted that the generated water on solid-liquid interface and a smaller reaction force restrict the continuous reduction reaction in low polarity solvents © 2014 Elsevier B.V. All rights reserved.

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