Electro-oxidation of amino-functionalized multiwalled carbon nanotubes |
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| Authors: | Yuanyuan Lu Xiuting Li Richard G. Compton |
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| Affiliation: | Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ UK.; Institute for Advanced Study, Shenzhen University, Shenzhen Guangdong 518060 China |
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| Abstract: | We report the electrochemistry of amino-functionalized multiwalled carbon nanotubes (MWCNTs-NH2) in the pH range from 0.3 to 6.4 using quantitative cyclic voltammetry (CV) and single entity electrochemistry measurements, making comparison with non-functionalized MWCNTs. CV showed the latter to both catalyze the solvent (water) decomposition and to undergo irreversible electro-oxidation forming oxygen containing surface functionality. The MWCNTs-NH2 additionally undergo an irreversible oxidation to an extent which is dependent on the pH of the solution, reflecting the variable amount of deprotonated amino groups present as a function of pH. Nano-impact experiments conducted at the single particle level confirmed the oxidation of both types of MWCNTs, showing agreement with the CV. The pKa of the amino groups in MWCNTs was determined via both electrochemical methods giving consistent values of ca. 2.5.A new and generic approach to the study of the oxidation of different forms of CNTs is found by using quantitative single entity and ensemble electrochemistry measurements. |
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