A Simple Synthesis of an Excellent Oxygen Reduction Catalyst: Nitrogen-Doped, Sharply-Mesoporous Carbon from Magnesium Salts

Thursday, 30 July 2015: 14:20
Dochart (Scottish Exhibition and Conference Centre)
D. Eisenberg, N. Yan, G. Rothenberg (University of Amsterdam), O. Mabayoje, and C. B. Mullins (University of Texas at Austin)
Any new oxygen reduction catalysts for practical low-temperature fuel cell applications must compete with the commercial platinum catalysts on efficiency and cost. Mesoporous nitrogen-doped carbon (N:C) has emerged as a leading alternative, mostly due to its high surface area, and the promise for low-cost production. While the best mesoporous N:C catalysts in the literature can operate on par with commercial platinum/carbon composites,their synthesis is complex and difficult – increasing their cost and rendering them impractical.

We present a particularly simple synthesis of N-doped carbon, starting from magnesium salts of nitrogen-containing ligands. Pyrolysis of the salts proceeds by the little-researched mechanism of self-templating – formation of similarly sized MgO nanoparticle cores, which are then washed out with dilute acid, leaving behind a narrow pore size distribution.

These carbons have high surface areas (>1400 m2/gr), nitrogen doping levels topping what is required for catalysis (>4%), and most interestingly, a very narrow pore size distribution (ranging from 10 to 20 nm for different carbons). Tested in alkaline ORR catalysis, these carbons compete successfully with commercial platinum-based electrodes, so they are efficient, cheap, and simple to prepare.

(1) W. Wei, H. Liang, K. Parvez, X. Zhuang, X. Feng, K. Müllen, Angew. Chem. 2014, 126, 1596.