Novel synthesis of N-doped porous carbons from collagen for electrocatalytic production of H2O2

Highly porous N-doped carbons for the electrocatalytic production of H2O2 via oxygen reduction were synthesized from paraformaldehyde cross-linked collagen through heating in vacuum at different temperatures (400-800 degrees C). SEM images and N-2 adsorption/desorption isotherms of such collagen-derived carbons reveal the formation of a sheet-like porous structure with increasing the carbonization temperature. A higher carbonization temperature favors the formation of a quaternary-N structure and the removal of oxygen-containing functional groups and therefore enhances the graphitic crystallinity, which were confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The collagen-derived carbon synthesized at 800 degrees C for 6h shows a good electrocatalytic activity for the four-electron oxygen reduction reaction (ORR). On the other hand, the carbons prepared at 400-800 degrees C for 4h possess a high selectivity for the H2O2 production at potentials more negative than 0.6V. The H2O2 production percentage for the carbon synthesized at 400 degrees C even reached 93%. In comparison with undoped carbons, the much more positive onset potentials and the nearly two-electron process of the ORR on these collagen-derived porous carbons reveal their unique electrocatalytic activity for H2O2 production. (C) 2012 Elsevier B.V. All rights reserved.