Renewable energy storage and conversion related devices, such as lithium-oxygen batteries (LOBs) and fuel cells, are facing a problematic issue that we need better catalysts to improve the electrochemical performances, commercialize and wide-spread those device to realize the energy mix of renewable and traditional energies. The new catalysts should be produced from abundant elements due to being achieved a realistic price of devices. Heteroatom doped carbons can be highly active electrocatalysts for oxygen reduction reaction (ORR). [Antonietti, M.; Fechler, N.; Fellinger, T.-P. Chem. Mater. 2013 , DOI: 10.1021/cm402239e.]  Recently, nitrogen doped carbon was shown to effectively catalyze oxygen evolution reaction (OER). [Yang, W.; Fellinger, T.-P. Antonietti, M. J. Am. Chem. Soc. 2011  , 133, 206]  Here, we introduce heteroatom doped carbonaceous compounds showing both ORR and OER, i.e., metal-free bifunctional catalysis. [Sakaushi, K.; Schipper, F.; Fellinger, T.-P.; Antonietti, M. Manuscript in preparation.] We applied our catalysts to the LOB system, which is one of the most promising next-generation rechargeable batteries having a high theoretical specific energy comparable to internal combustion engines. [Lu, Y.-C.; Gallant, B. M.; Kwabi, D. G.; Harding, J. R.; Mitchell, R. R.; Whittinghamd, M. S.; Shao-Horn, Y. Energy Environ. Sci. 2013  , 6, 750.]  The LOB using our catalysts shows a better discharge property (= ORR) compared to standard carbon and a high performance at recharging (= OER). By using our catalysts, we observed an average discharge voltage of 2.7 V vs. Li/Li+ and an average recharge voltage of 3.8 V vs. Li/Li+ at a low current density of 20 mA g-1 at the first cycle. Especially, the polarization at the recharge reaction is about 0.8 V compared to the electro-motive force of the reaction (= 2.96 V vs. Li/Li+). This value is quite promising, even compared to the nanoporous gold catalyst showing the average recharge polarization of 0.5 V. [Peng, Z.Q.; Freunberger, S. A.; Chen, Y.H.; Bruce, P. G. Science 2012  , 337, 563.] Our results will encourage the further investigations on abundant and high-performance catalysts without noble metals, even without metals. At the conference, the morphology of our catalysts will be shown and the electrochemical catalytic activities depending on synthetic conditions will be discussed.

Application of nanostructured metal-free bifunctional catalysis: In case of lithium-oxygen batteries

247th National Meeting (2014)

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