Improved electrocatalytic activity of carbon materials by nitrogen doping

The metal-based catalysts have been playing a major role in various industrial processes, whereas carbon based nanomaterials have recently been demonstrated to be promising metal-free alternatives for low cost catalytic processes. The doping of nitrogen in carbon and the electrocatalytic properties of the nitrogen doped carbon for oxygen reduction reactions are investigated in this article. We propose a simple method for doping nitrogen in various carbon materials like carbon black and ketjen black, and comparatively studied their physical and electrochemical characteristics. Raman and XPS analyses show significant peak shifts of their characteristic peaks caused by nitrogen doping on the surface of carbon materials. N-doped carbons show higher surface area in Brunauer, Emmett and Teller surface area analysis and more porous structure than undoped carbons in scanning electron microscope images. The N-doped sample was also ball milled to study the surface properties. All samples, i.e. undoped, N-doped and N-doped ball-milled carbons were compared for electrocatalytic activity by cyclic voltammetry and oxygen reduction reaction measurements. Nitrogen doped carbons exhibit better electrocatalytic activity with high mass activity and positive shift of peak potential than undoped samples with electron transfer number of 3.6 close to that of commercial Pt/C. (C) 2013 Elsevier B.V. All rights reserved.