The Electrochemical Behavior of Carbon Fiber Microelectrodes Modified with Carbon Nanotubes Using a Two-Step Electroless Plating/Chemical Vapor Deposition Process.

Longsheng Lu,Kwok Teh,Yingxi Xie,Yong Tang,Zhenping Wan,Linsheng Liang

doi:10.3390/s17040725

Abstract

Carbon fiber microelectrode (CFME) has been extensively applied in the biosensor and chemical sensor domains. In order to improve the electrochemical activity and sensitivity of the CFME, a new CFME modified with carbon nanotubes (CNTs), denoted as CNTs/CFME, was fabricated and investigated. First, carbon fiber (CF) monofilaments grafted with CNTs (simplified as CNTs/CFs) were fabricated in two key steps: (i) nickel electroless plating, followed by (ii) chemical vapor deposition (CVD). Second, a single CNTs/CF monofilament was selected and encapsulated into a CNTs/CFME with a simple packaging method. The morphologies of as-prepared CNTs/CFs were characterized by scanning electron microscopy. The electrochemical properties of CNTs/CFMEs were measured in potassium ferrocyanide solution (K4Fe(CN)6), by using a cyclic voltammetry (CV) and a chronoamperometry method. Compared with a bare CFME, a CNTs/CFME showed better CV curves with a higher distinguishable redox peak and response current; the higher the CNT content was, the better the CV curves were. Because the as-grown CNTs significantly enhanced the effective electrode area of CNTs/CFME, the contact area between the electrode and reactant was enlarged, further increasing the electrocatalytic active site density. Furthermore, the modified microelectrode displayed almost the same electrochemical behavior after 104 days, exhibiting remarkable stability and outstanding reproducibility.

Highlights

Microelectrodes are miniaturized working electrodes with micrometer dimensions that can be made with metallic or non-metallic conductors
Using the aforementioned two-step method, a layer of coaxial carbon nanotubes (CNTs) was successfully grown on the carbon fiber (CF) surface
The results indicate that all of the cyclic voltammetry (CV) curves all of the CV curves are nearly identical with constant response currents, indicating that the areCNTs/Carbon fiber microelectrode (CFME)

Summary

Introduction

Microelectrodes are miniaturized working electrodes with micrometer dimensions that can be made with metallic or non-metallic conductors. Due to its tiny dimension, a microelectrode exhibits several unique electrochemical properties, such as a negligible ohmic drop, high detection sensitivity, high mass transfer rate, and enhanced signal-to-noise ratio [1]. These properties have led to its extensive applications in micro biosensors [2] and chemical analysis sensors [3]. Typical microelectrode materials include platinum, gold, silver, and carbon fiber [1]. Carbon fiber (CF) is an attractive electrode material because of its great physicochemical and electrochemical properties, such as its good electrical and thermal conductivities, adequate corrosion resistance, low density, and elasticity [4].

Methods

Results

Conclusion