Electrocatalytic Oxidation of Hydrogen Peroxide and Cysteine at a Glassy Carbon Electrode Modified with Platinum Nanoparticle-deposited Carbon Nanotubes

Abstract

Dispersed metal particles exhibit excellent catalytic activity that closely relates to their minimized diameters. The micro and nano particles trend to have excellent quality in chemical and electrochemical reactions. For this purpose, metal particles have been successfully dispersed and decorated on some substrates such as carbon and conductive polymers to make catalyst. [1][2][3] It is essential to find ways to further reduce diameters of these metal particles to promote their catalytic activity. The diameters of nano particles vary with the medium and the substrates on which they are made. As one typical nano material, carbon nanotubes (CNT) whose diameters vary from 0.33 to less than 100 nanometers were made up with hexagonal lattices of carbon. Because of their characteristic electron conductivity valves, pore structures and absorption abilities they are fit for metal substrates. Various metals and alloys were deposited on them. [4][5][6][7][8][9] Electrodes modified with CNT and used to analyze biomolecules have received much interest. [10][11][12][13][14][15][16][17][18] However, no preparation of electrodes modified by nano metal particlesdecorated carbon nanotubes has been reported. In our research, a glassy carbon electrode modified with platinum nano particles decorated on carbon nanotubes (Pt-CNT/GCE) was developed. Carbon nanotubes decorated with platinum nano particles (Pt-CNT) were obtained by chemical method, 19 and then were immobilized on the surfaces of GCE electrodes. Electrochemical determinations using metals particle-modified electrodes have been focused on. [20][21][22][23][24][25][26][27] On the other hand, it is also important to prepare an amperometric sensor for the measurement of hydrogen peroxide and cysteine. 28 In the paper, electrocatalytic oxidation for hydrogen peroxide and cysteine at Pt-CNT/GCE was investigated. Due to the nano-sized platinum particles deposited on CNT, the currents at Pt-CNT/GCE were almost 3-times higher and the electrode reaction rates were obviously faster, compared with bare platinum electrode results. So, the Pt-CNT/GCE has high electro-catalytic activity, which is suitable for preparing enzyme electrodes with better sensitivity, repeatability and stability. Experimental Equipment and reagentsElectrochemical experiments were carried out using a CHI660B electrochemical workstation (CHI Instruments Inc., US). A glassy carbon electrode (φ = 2 mm) modified with Pt-CNT was used as the working electrode. A platinum wire and KCl saturated Ag/AgCl electrodes were employed as the counter electrode and a reference electrode, respectively. For comparison of the electro-catalytic activities, a bare Pt electrode (φ = 2 mm) was also used as a working electrode.Carbon nanotubes (inner φ = 4 -8 nm, outer φ = 10 -30 nm) were supplied by the Dept. of Materials, Zhejiang University; they were synthesized by Chemical Vapor Deposit method. 0.1 mol/L phosphate buffer solution (pH 7.0) was prepared by freshly distilled water. 10 mg/mL H2PtCl6 was made in 6 mol/L HCl solutions...

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“…, which is close to the previous reported [35,43,44]. It can also be noted that by increasing the sweep rate the peak potential for the catalytic reduction of H 2 O 2 shifts to more negative values and a plot of peak current vs. square root of scan rate deviates from linearity, suggesting a kinetic limitation in the reaction between the redox sites of thionin and analyte.…”

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“…The Rh-DENs modified glassy carbon electrode is comparable and better than many other modified electrodes [34][35][36][37][38] in terms of low detection limit, high sensitivity and low potential detection of hydrogen peroxide.…”

Electrosorption of Os(III)-complex at single-wall carbon nanotubes immobilized on a glassy carbon electrode: Application to nanomolar detection of bromate, periodate and iodate

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