Abstract
CuBi2O4 synthesized by thermolysis of a new Bi(III)-Cu(II) oxalate coordination compound, namely Bi2Cu(C2O4)4·0.25H2O, was tested through its integration within carbon nanofiber paste electrode, namely CuBi/carbon nanofiber (CNF), for the electrochemical detection of amoxicillin (AMX) in the aqueous solution. Thermal analysis and IR spectroscopy were used to characterize a CuBi2O4 precursor to optimize the synthesis conditions. The copper bismuth oxide obtained after a heating treatment of the precursor at 700 °C/1 h was investigated by an X-ray diffraction and scanning electron microscopy. The electrochemical behavior of CuBi/CNF in comparison with CNF paste electrode showed the electrocatalytic activity of CuBi2O4 toward amoxicillin detection. Two potential detections, with one at the potential value of +0.540 V/saturated calomel electrode (SCE) and the other at the potential value of −1.000 V/SCE, were identified by cyclic voltammetry, which were exploited to develop the enhanced voltammetric and/or amperometric detection protocols. Better electroanalytical performance for AMX detection was achieved for CuBi/CNF using differential-pulsed and square-wave voltammetries than others reported in the literature. Very nice results obtained through anodic and cathodic currents recorded at +0.750 V/SCE and −1.000 V/SCE in the same time period using a pseudo multiple-pulsed amperometry technique showed the great potential of the CuBi/CNF paste electrode for practical applications in amoxicillin detection in aqueous solutions.
Highlights
X-ray diffraction (XRD) and SEM analyses indicated that phase-pure CuBi2 O4 particles with an average particle size of 893.3 nm were obtained after calcination at 700 ◦ C for 1 h
Cyclic voltammetric studies showed the superiority of CuBi/carbon nanofiber (CNF) paste through the redox system manifested within intrinsic CuBi2 O4
The voltammetric detection methods based on differential-pulsed voltammetry operated under 0.02 V as a step potential and 0.100 V as a modulation amplitude that allowed reaching the lowest limit of detection of 0.15 μM, while a fast and stable response characterized by the highest sensitivity of 653 μA μM cm−2 was achieved with square-wave voltammetry operated under a 0.02 Vas step potential and a 0.100 V as a modulation amplitude, frequency of 20 Hz, and a scan rate of 0.4 V s−1
Summary
Electrochemical sensors represent the main category of sensors due to their advantages of fast response, simplicity, and versatility Their electroanalytical performance depends on the electrode type correlated with the electrochemical techniques. Several electrochemical detection methods of AMX using carbon-based and modified electrodes have been reported [26,27,28], but more improvement of the electroanalytical performance is required for which new composition of the electrode, which represents the core of the electrochemical detection, should be developed and tested. Bi(III)-Cu(II) oxalate coordination compound at 700 ◦ C/h was used to modify the carbon nanofiber paste by simple mixing in paraffin oil as a CuBi/CNF electrode to enhance the performance of the electrochemical detection of amoxicillin. The new electrode was tested comparatively with CNF paste electrode in AMX detection using conventional and advanced voltammetric and amperometric techniques
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