Fabrication of Polyaniline Ni-Complex Catalytic Electrode by Plasma Deposition for Electrochemical Detection of Phosphate through Glucose Redox Reaction as Mediator

Hyun-Woong Lee,Seong-Ho Choi,Jae-Ni Yoo,In-Keun Yu

doi:10.3390/catal12020128

Hyun-Woong Lee, Seong-Ho Choi + Show 2 more

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https://doi.org/10.3390/catal12020128

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Abstract

We report here the preparation and characterization of polyaniline Ni-complex catalytic electrode by one-pot plasma deposition for the electrochemical detection of phosphate via the redox reaction of glucose. We first prepared a precursory solution by combining NiCl2 and 3-aminobenzoic acid in a mixed solution of methanol (MeOH) and water, and adding aniline as a conductive polymeric precursor for increasing the electron transfer potential. We then synthesized the catalytic electrode in a one-step cold plasma process by preparing the precursors on ITO glass. We characterized the obtained Ni-coordinate catalytic electrode via X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM), and electrochemical methods. Electrochemical characterization produced stable redox properties of Ni3+/Ni2+ couples in a 0.1 M NaOH solution. Cyclic voltametric experiments have drastically increased electrocatalytic oxidation and reduction of glucose by increasing the concentration of phosphate (PO43−) ions using the prepared Ni-modified catalytic electrodes. From these results, the prepared catalytic electrode could be used as the electrochemical sensor for phosphate in actual water.

Highlights

Quantitative evaluation of phosphates, both of inorganic compounds and organic compounds, is important in biomedical research, biological diagnosis, and environmental monitoring [1,2,3]
We found that a polyaniline Ni-complex catalytic electrode can be applied as an electrochemical oxidation for glucose in the presence of high concentrations of phosphate
By examining the water contact angles, we determined that the contact angle of the bare indium tin oxide (ITO) electrode, No 1 was 77◦ and the contact angles of the polyaniline Ni-coordinated catalytic electrodes, No 2, No 3, and No 4 were 60◦, 53◦, and 51◦, respectively, at room temperature

Summary

Introduction

Quantitative evaluation of phosphates, both of inorganic compounds and organic compounds, is important in biomedical research, biological diagnosis, and environmental monitoring [1,2,3]. The sensing range of phosphorus is between 0.2 in 10 mg/L in natural and waste waters and between 0.2 and 50 mg/kg in soil. A maximum permissible concentration of phosphate in river water is 0.32 μM and ranges between 0.0143 and 0.143 mM in wastewater [4]. The concentration of phosphate ions in human saliva is variable, ranging from between 5 and 14 mM [5]. Adult human serum with a range of 0.81 to 1.45 mM PO43− was used [6]. Many researchers have developed various detection methods for phosphate such as phosphate ion selective electrodes [7], chromatography [8], spectroscopy [9], and the development of sensors exploiting enzymatic reactions [10,11]. Little has been reported about electrochemical detection, which is known as a simpler method those described above

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