Metal Complexes of 4,4′-Bipyridine: Characterization, Electrochemical Performance and Application in High Sensitivity Detection of H2O2

Abstract

Three metal complexes composed of divalent transition metals such as Cu(II), Ni(II) and Co(II) metal ions from their corresponding aqueous salt and 4,4′-Bipyridine (BPy) were prepared by hydrothermal reaction in a Teflon-lined autoclave, and were also characterized by Fourier transform infrared spectra (FT-IR), UV-vis spectra and scanning electron microscopy (SEM). Furthermore, they were effectively used to prepare modified carbon paste electrodes (M-BPy/CPE) to investigate electrochemical performances of these complexes by electrochemical impedance spectroscopy (EIS) and Cyclic voltammograms (CVs). It was found that hydrogen peroxide (H2O2) could inhibit the electron transfer of M-BPy complexes on the electrode surface due to the generation of M-BPy complexs N-oxide. Based on these results, no need for enzyme immobilization, Cu-BPy/CPE was used to construct electrochemical sensor platform for direct detection of H2O2. A good linear relationship between peak current inhibition rate and concentration logarithm of H2O2 was obtained on Cu-BPy/CPE in the range of 2.0 × 10−9–2.0 × 10−3 M with the limit of quantification (LOQ) of 2.3 × 10−9 M (S/N = 10) and the limit of detection (LOD) of 7.0 × 10−10 M (S/N = 3). Furthermore, the developed sensor was successfully applied in the determination of H2O2 in human serum samples with the recoveries from 93.6% ∼ 99.3%.