Nitrogen-self-doped carbon with a porous graphene-like structure as a highly efficient catalyst for oxygen reduction† Jian Zhang, a Qidong Li, b Hui Wu, a Chenyu Zhang, a Kun Cheng, a Huang Zhou, a Mu Pan a and Shichun Mu * a A non-noble metal nitrogen (N)-doped carbon catalyst, with a porous graphene-like structure, is prepared by pyrolyzing polyaniline with addition of urea. Herein, urea not only serves as a N source similar to polyaniline by incorporating N atoms into the carbon matrix, but plays a key role in forming the porous graphene-like structured carbon nanosheet. The electrochemical characterization shows that the prepared catalyst with a unique graphene-like structure exhibits an oxygen reduction reaction (ORR) activity that outperforms that of the commercial Pt/C catalyst in alkaline media, its half-wave potential nearly 30 mV more positive than Pt/C, and both superior stability and fuel (methanol and CO) tolerance to Pt/C. Significantly, such a catalyst also exhibits a good ORR activity which is comparable to Pt/C, as well as a higher stability than Pt/C in acidic media. Introduction Low temperature fuel cells (LTFCs) have been considered promising energy conversion devices due to their high power density, high efficiency, and environmental friendliness. 1,2 As electrocatalysts for LTFCs, Pt-based nanoparticles supported on carbon have been regarded as state-of-the-art catalysts for the oxygen reduction reaction (ORR) at the cathode. However, low natural availability of precious Pt metal and its high cost are key concerns in the commercialization of LTFCs. 3–5 Besides, Pt- based catalysts still suffer from serious intermediate tolerance, such as CO poisoning and methanol crossover as well as poor stabilities in an electrochemical environment. 1,6–10 To solve such issues, considerable effort has been made to explore non-noble metal catalysts (NNMCs) to solve the intrinsic drawbacks of Pt- based catalysts. To date, N-doped carbon based catalysts have attracted considerable attention as one of the most promising candidates owing to their low cost and high catalytic activities as well as excellent CO and methanol poisoning resistances. However, the development of simple and cost-effective strategies for synthe- sizing high specic surface area carbon-based materials with porous structural and functional properties is one of the fore- most challenges in materials chemistry at present. So far, much effort has been devoted to increasing the surface area of NNMCs by using sacricial inorganic hard templates, such as ordered mesoporous silica (OMS: e.g., SBA-15, MCM-41, and ZSM- 12), 8,11,12 nano-silicon, 1,11,13 anodic alumina oxide, 14 and nano- metal oxides, 15,16 and by using high specic surface area carbon materials as supports (such as mesoporous carbon and gra- phene), 16,17 high specic surface area metal–organic frame- works (MOFs: e.g., MOF-5, Al-PCP, and ZIF-8) as precursors, 3,4,17–21 and other miscellaneous techniques. 7,22 In spite of their advantages, the majority of synthesis routes for porous carbon materials typically involve multi-step proce- dures: rst, the synthesis of various hard templates followed by the inltration and impregnation of the carbon precursor and then cross-linking and high temperature carbonization of precursors; aer that, the removal of templates via strong alkali, acidic or caustic dissolution from the inorganic matrix. It is not hard to see that such processes have drawbacks such as high cost, environmental unfriendliness, time-consumption and complex routes, seriously limiting the development of nano- structured carbon materials on the industrial scale. In addition, N-doped graphene has attracted a great deal of interest for ORR in recent years due to its good catalytic activity, high electrical conductivity, ultra-high specic surface area and good chemical stability. 22–24 However, the preparation of high quality graphene is still very complicated and expensive, which also limits its large-scale use in LTFCs. Fortunately, a recent study shows that the graphene-like carbon nanosheet can also provide a sophisticated electron pathway and superior structural stability for the electrocatalyst. Thus, the N-doped graphene-like a State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China. E-mail: msc@whut.edu.cn; Fax: +86 27 87879468; Tel: +86 27 87651837 b WUT-Harvard Joint Nano Key Laboratory, Wuhan University of Technology, Wuhan 430070, China † Electronic supplementary information (ESI) available: XPS tted results, Raman spectra, EIS, K–L equation, and some of the electrochemical performances. See DOI: 10.1039/c5ta00547g Cite this: J. Mater. Chem. A, 2015, 3, 10851 Received 22nd January 2015 Accepted 6th April 2015 DOI: 10.1039/c5ta00547g www.rsc.org/MaterialsA This journal is © The Royal Society of Chemistry 2015 J. Mater. Chem. A, 2015, 3, 10851–10857 | 10851 Journal of Materials Chemistry A PAPER Published on 08 April 2015. Downloaded by WUHAN UNIVERSITY OF TECHNOLOGY on 15/05/2015 18:10:56. View Article Online View Journal | View Issue