H2O2 Detection at Carbon Nanotubes and Nitrogen-Doped Carbon Nanotubes: Oxidation, Reduction, or Disproportionation?

Jacob M. Goran, Ethan N.H. Phan, Carlos A. Favela, Keith J. Stevenson

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63 Citations (Scopus)

Abstract

The electrochemical behavior of hydrogen peroxide (H2O2) at carbon nanotubes (CNTs) and nitrogen-doped carbon nanotubes (N-CNTs) was investigated over a wide potential window. At CNTs, H2O2 will be oxidized or reduced at large overpotentials, with a large potential region between these two processes where electrochemical activity is negligible. At N-CNTs, the overpotential for both H2O2 oxidation and reduction is significantly reduced; however, the reduction current from H2O2, especially at low overpotentials, is attributed to increased oxygen reduction rather than the direct reduction of H2O2, due to a fast chemical disproportionation of H2O2 at the N-CNT surface. Additionally, N-CNTs do not display separation between observable oxidation and reduction currents from H2O2. Overall, the analytical sensitivity of N-CNTs to H2O2, either by oxidation or reduction, is considerably higher than CNTs, and obtained at significantly lower overpotentials. N-CNTs display an anodic sensitivity and limit of detection of 830 mA M-1 cm-2 and 0.5 μM at 0.05 V, and a cathodic sensitivity and limit of detection of 270 mA M-1 cm-2 and 10 μM at -0.25 V (V vs Hg/Hg2SO4). N-CNTs are also a superior platform for the creation of bioelectrodes from the spontaneous adsorption of enzyme, compared to CNTs. Glucose oxidase (GOx) was allowed to adsorb onto N-CNTs, producing a bioelectrode with a sensitivity and limit of detection to glucose of 80 mA M-1 cm-2 and 7 μM after only 30 s of adsorption time from a 81.3 μM GOx solution.

Original languageEnglish
Pages (from-to)5989-5996
Number of pages8
JournalAnalytical Chemistry
Volume87
Issue number12
DOIs
Publication statusPublished - 16 Jun 2015
Externally publishedYes

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