Nitrogen-doped and nanostructured carbons with high surface area for enhanced oxygen reduction reaction

The development of highly-efficient, inexpensive, and stable electrocatalysts as alternatives to platinum-based materials for the oxygen reduction reaction (ORR) is crucial to various energy storage and conversion systems, such as metal-air batteries and fuel cells. Herein, we have successfully prepared three kinds of hierarchically porous nitrogen-doped carbons with different morphologies (particles, nanowires, and nanoribbons) through a carbon dioxide activation process. The porous properties and catalytic performance of the nitrogen-doped porous carbons are dramatically and clearly improved through changing the morphology of polypyrrole precursors. Among these nitrogen-doped porous carbons, the nitrogen-doped and nanostructured carbon with the morphology of nanoribbons possesses the highest specific surface area (1130 m2 g−1) and displays the best ORR activity with the largest electron transfer number (3.67) and the most positive onset potential (0.86 V vs. RHE) in oxygen-saturated aqueous KOH solution (0.1 M). This enhanced ORR performance can be attributed to nitrogen-doping, a hierarchically porous structure, and large specific surface area.

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