Facile synthesis of N-doped mesoporous carbon materials with highly graphitic properties for oxygen-reduction electrochemical catalysts

摘要

Nitrogen-doped graphitic carbon materials exhibit high electrocatalytic activities,1, 2 superior electrical conductivities,3 and high thermal and chemical stabilities,4 making them promising non-precious metal or metal-free catalysts. N-doped graphitic mesoporous carbon materials are typically synthesized either by pyrolyzing N-containing graphitizable precursors5 or by chemical vapor deposition of N-containing precursors6 in the presence of transition metal oxide catalysts. We have developed a facile synthesis method based on inexpensive precursors to prepare N-doped mesoporous carbon materials with highly graphitic properties, high surface areas, and tunable pore dimensions. Simple pyrolysis of high-N-content organic materials and transition metal salts (iron, nickel, cobalt, or manganese nitrates) with mesoporous silica templates can yield N-doped mesoporous carbon materials with favorable electrocatalyst properties. Synthesis conditions of N-doped graphitic mesoporous carbon materials have been optimized to yield oxygen reduction activities under alkaline or acidic conditions, as evaluated by linear sweep voltammetry with a rotating disk electrode. Optimized N-containing graphitic mesoporous carbon catalysts synthesized with transition metal salts provide excellent oxygen reduction electrocatalytic properties (activity, stability, and selectivity) under alkaline conditions that are comparable or superior to commercially available carbon-supported platinum catalysts.