Electrochemical estimation of the active site density on metal-free nitrogen-doped carbon using catechol as an adsorbate. Issue 37 (12th September 2017)

• Record Type: Journal Article
• Authors: Chakraborty, Arup; Devivaraprasad, Ruttala; Bera, Bapi; Neergat, Manoj
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 37(2017)
• Page Start: 25414
• Page End: 25422
• Publication Date: 2017-09-12
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c7cp04285j
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : An electrochemical method to estimate the active site density of metal-free electrocatalysts using catechol adsorption. Abstract : Carbon is heat-treated with a nitrogen-containing precursor (ammonia) to obtain nitrogen-doped carbon and the composition is estimated using CHN and XPS analysis. The active site density of the carbon and nitrogen-doped carbon is quantified using 1, 2-dihydroxybenzene (catechol) molecules as an adsorbate in phosphate buffer (pH 7) solution. The features of the voltammograms of the catechol-adsorbed high surface area carbon and nitrogen-doped carbon are similar to that of the polished nitrogen-grafted glassy carbon electrode (GCE) reported in the literature. At the same time, the polished GCE does not show any well-defined catechol adsorption features. It is found that the adsorption charge (obtained by integrating the peak area, after subtracting the background) is in the order of N/C 900 > N/C 1000 > N/C 800 > N/C 700 > C. A similar trend is observed in their oxygen reduction reaction (ORR) activity in 0.1 M KOH. Moreover, the turnover frequency (ToF) of the catalysts is calculated and it is comparable to that reported in the literature using other methods for non-precious catalysts. Therefore, the adsorption charge can be correlated with the active site density of the carbon and nitrogen-doped carbon samples.