Fuel cells have become promising alternatives as sustainable energy conversion devices over the last few decades. A critical issue in the commercialization of fuel cells and metal-air batteries is the development of high-efficiency, cost-effective catalysts for the oxygen reduction reaction (ORR). Pt and its alloys are the best electrocatalyst for ORR, but their scarcity and high price has limited their use. Renewable and sustainable materials represent cost-effective alternatives as precursors for fuel cell electrodes. Herein, highly porous nitrogen and phosphorus dual-doped carbon materials were obtained by chitin and coconut husk for electrochemical catalysis of ORR. We directly synthesized N/P-doped carbon from chitin via facile activation and pyrolysis using phosphoric acid. Besides coconut husk as carbon precursors, nitrogen precursors such as ammonium chloride, urea and polyaniline were also used after activation of the starting material. The morphology of the carbon materials assessed by scanning electron microscope (SEM) and transmission electron microscope (TEM) showing sheet-like structure of carbonized materials. The obtained porous carbons exhibited very high surface area, up to 1220 m2/g and pore volume of about 1.3 m3/g. The elemental analysis by X-ray photoelectron (XPS) indicated successful incorporation of nitrogen and phosphorous in the carbon structure, as indicated at N 1s and P 2p XPS fingerprints. In addition, deconvolution of N 1s peaks showed significant ratio of N-graphitic/N-pyridinic functionalities, which acts as, as active sites for the oxygen reduction. Electrochemical analysis of ORR was performed in a three-electrode cell compartment using 0.1 M KOH electrolyte and exhibited a high electrocatalytic activity for ORR, comparable to that of commercial 20% Pt-C catalysts. The results suggested a facile and promising route for economical and sustainable use of residual biomass towards value-added products, particularly, as shown in this study, for the development of effective metal-free electrocatalysts for green energy production.

N/P dual-doped porous carbon synthesized from coconut husk and chitin as an efficient electrocatalyst for the oxygen reduction reaction

251st National Meeting (2016)

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