DOI: 10.1002/celc.201402231 One-Pot Synthesis of Cobalt-Incorporated Nitrogen-Doped Reduced Graphene Oxide as an Oxygen Reduction Reaction Catalyst in Alkaline Medium Tintula Kottakkat and Michael Bron* [a] 1. Introduction Electrochemical reduction of oxygen in alkaline media is a sub- ject of growing interest for electrochemical energy conversion and storage devices, such as alkaline fuel cells, metal–air bat- teries, and chloralkali electrolysis with air-depolarized cathodes. [1] Among these, fuel cells offer the advantage of high-efficiency energy conversion. However, kinetic limitations of the oxygen reduction reaction (ORR) at the cathode lead to large overpotential losses, thereby lowering the energy effi- ciency. The successful large-scale implementation of fuel cells, therefore, depends on the advent of active, stable, and selec- tive ORR catalysts that are preferably free from precious metals. So far, a large variety of catalyst materials have been investi- gated for the ORR in alkaline media. To date, platinum has shown the highest activity in both alkaline and acidic media. In the past few years, some low-cost alternatives to platinum such as doped carbonaceous materials, metal–nitrogen com- plexes on carbonaceous materials, various transition metals, metal oxides, metal carbides, metal macrocycles, perovskites, and spinels have made promising advances. [2] However, new strategic materials have yet to be developed with the aim of developing low-cost catalysts for the ORR with high catalytic activity. Recently, graphene, which is composed of thin sheets of sp 2 - hybridized carbon atoms, has attained tremendous research in- terest as an electrode material for energy conversion devices. The attractive properties of graphene in the context of cataly- sis, such as high surface area, good chemical stability, excellent conductivity, unique graphitic basal plane structure, and flexi- bility in surface modification, make it advantageous as a cata- lyst support material in fuel cell electrodes. However, the chemically stable structure of graphene with the sp 2 -hybridized carbon network limits its application as a catalyst due to the absence of sufficiently active sites. In a defect-free graphene, the limited activity arises from unsaturated carbon atoms at the edges of the graphene layer rather than from carbon atoms in the basal planes. [3] Functionalization and incorpora- tion of heteroatoms (B, N, S, or P) into the graphene structure are found to modify the electronic structure, thereby increas- ing the catalytic activity for the ORR [4] to an acceptable level. Recently, cobalt-based oxides have shown promising activity in alkaline media for the ORR. For instance, Guo et al. deposited presynthesized Co/CoO nanoparticles on the surface of gra- phene (G) to form G Co/CoO, which showed enhanced ORR activity compared with Co/CoO nanoparticles and Co/CoO nanoparticles deposited on Ketjen black. [5] This reveals that specific interactions between metal or metal oxide particles with the carbonaceous support can lead to high ORR activity, as also demonstrated by Liang et al. for Co 3 O 4 nanocrystals on graphene (nitrogen-doped mildly reduced graphene oxide). [6] Herein, we report a facile method for the synthesis of cobalt oxides on nitrogen-doped graphene (Co/NrGO; NrGO = nitro- gen-doped reduced graphene oxide) through a single-step py- rolysis of the precursors of cobalt, nitrogen, and graphene. Herein, we chose graphite oxide (GO) as a precursor for gra- phene considering the most economical way to produce scalable amounts of graphene-based materials from GO, which Cobalt-incorporated nitrogen-doped reduced graphene oxide (Co/NrGO) as a catalyst for the oxygen reduction reaction is prepared in a single step by thermal reduction of graphene oxide to reduced graphene oxide (rGO) in the presence of a cobalt salt and 1,10-phenanthroline as a nitrogen precursor. Cobalt is identified as cobalt oxide (CoO) in the hybrid. Both the cobalt and nitrogen contents in Co/NrGO are higher than those in cobalt- or nitrogen-free samples; this indicates that cobalt and 1,10-phenathroline mutually enhance incorporation into the material. An almost four-electron transfer is observed as the average per oxygen molecule, and Co/NrGO demon- strates highly improved activity in comparison with NrGO and rGO. CoO and nitrogen-doped moieties may be acting as active centers for oxygen reduction individually or synergisti- cally. With a loading of less than 2 wt% cobalt in Co/NrGO, ap- preciable activity is already observed. Moreover, the high selec- tivity for oxygen reduction over methanol oxidation for Co/ NrGO is demonstrated, making this hybrid a promising catalyst for direct methanol alkaline fuel cells. [a] Dr. T. Kottakkat, Prof. Dr. M. Bron Institut für Chemie—Technische Chemie I Martin-Luther-Universität Halle-Wittenberg von-Danckelmann-Platz 4, 06120 Halle/Saale (Germany) E-mail : michael.bron@chemie.uni-halle.de Supporting Information for this article is available on the WWW under http://dx.doi.org/10.1002/celc.201402231.  2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim ChemElectroChem 0000, 00, 1 – 10 &1& These are not the final page numbers! ÞÞ CHEMELECTROCHEM ARTICLES