期刊
ELECTROCHIMICA ACTA
卷 55, 期 14, 页码 4319-4327出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2009.02.102
关键词
Single-walled carbon nanotubes; Cobalt nanoparticles; Electron transfer behaviour; Impedance spectroscopy; Adsorption; Nitrite detection
资金
- University of Pretoria
- NRF [2073666]
- Research Infrastructure Support Programme (RISP) [65305]
- Nanotechnology Flagship Programme (NFP) [68338]
- DST/MINTEK (NIC)
The electrochemical decoration of edge plane pyrolytic graphite electrode (EPPGE) with cobalt and cobalt oxide nanoparticles integrated with and without single-walled carbon nanotubes (SWCNTs) is described. Successful modification of the electrodes was confirmed by field emission scanning electron microscopy (FESEM). AFM and EDX techniques. The electron transfer behaviour of the modified electrodes was investigated in [Fe(CN)6](3-/4-) redox probe using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and discussed. The study showed that cobalt nanoparticles modified electrodes exhibit faster electron transfer behaviour than their oxides. The catalytic rate constant (K) obtained at the EPPGE-SWCNT-Co for nitrite at pH 7.4 and 3.0 are approximately the same (similar to 3 x 10(4) cm(3) mol(-1) s(-1)) while the limits of detection (LoD = 3.3 delta/m) are in the mu M order. From the adsorption stripping voltammetry, the electrochemical adsorption equilibrium constant beta was estimated as (13.0 +/- 0.1) x 10(3) M-1 at pH 7.4 and (56.7 +/- 0.1) x 10(3) M-1 at pH 3.0 while the free energy change (Delta G degrees) due to the adsorption was estimated as -6.36 and -10.00 kJ mol(-1) for nitrite at pH 7.4 and 3.0, respectively. (C) 2009 Elsevier Ltd. All rights reserved.
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