One of the central challenges for the commercial application of fuel cells are the high costs of the platinum@carbon (Pt/C) catalyst for the oxygen reduction reaction (ORR).1 We and others were showing that porous nitrogen doped carbons (NDCs) can serve as alternative ORR-catalysts.2,3 NDCs can perform as good as Pt/C under alkaline conditions and even outperform Pt/C referring to stability and lifetime.3 However, mechanistic discussions are still ongoing and rather expensive methods for porogenesis are widely employed. Among the various methods to obtain highly porous NDCs the ionothermal approach (the so called “salt templating”) is - due to its facility, scalability and the ability to achieve high surface area - an explicitly interesting alternative.4 Herein we adopt the original procedure to the employment of an inexpensive, biomass-derived precursor and the use of less corrosive inorganic salt i.e. ordinary NaCl. This way micro- and mesoporous NDCs with high specific surface area of 2900 m2g-1 and large porosity (&lt; 5 cm3g-1) are obtained. In the presentation we will present a new pore tuning tool allowing a continuous and highly precise variation of the mesopore size and additional macropore formation. Surprisingly, ORR measurements under alkaline conditions reveal a strong influence of the pore structure on the half wave potential (E1/2) and indicate a predominance of porosity effects if compared to nitrogen content or specific surface area (Figure 1). The optimization of the pore structure leads to a catalyst with a high selectivity towards the 4 e- process and an outstanding E1/2 for non-metal catalysts of ~ 880 mV (vs. RHE). (1) Debe, M. K. Nature 2012, 486, 43. (2) Yang, W.; Fellinger, T.-P.; Antonietti, M. Journal of the American Chemical Society 2011, 133, 206. (3) Liu, R.; Wu, D.; Feng, X.; Müllen, K. Angewandte Chemie 2010, 122, 2619. (4) Fechler, N.; Fellinger, T.-P.; Antonietti, M. Advanced Materials 2013, 25, 75.

Pore tuning towards highly active nitrogen doped carbon electrocatalysts

251st National Meeting (2016)

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