Highly active catalysts for the oxygen reduction reactions (ORR) have long been regarded as a key to optimize the performance of fuel cells because of the kinetic sluggishness of ORR with a complex four-electron transfer process. [1] Although platinum-based catalysts for ORR were developed for the Apollo lunar mission as early as the 1960s, their largescale commercial applications have been precluded by high costs and scarcity of platinum. [2] Therefore, numerous efforts have been devoted to reduce or substitute Pt-based catalysts by employing Pt-based alloys, [3] nonprecious metal catalysts, [4] enzymatic electrocatalysts, [5] or nitrogen-enriched carbonaceous materials. [1a,b, 2a, 6] Very recently, nitrogen-doped carbon nanotubes [1a] and mesoporous graphitic arrays [6a] have been proposed as potential metal-free catalysts for ORR because they not only exhibit excellent electrocatalytic activity but also possess the advantages of low costs, long durability, and environmental friendliness. Moreover, quantum mechanical calculations [7] and experimental investigations [6a, 8] both reveal that the incorporation of nitrogen, especially the pyridinic or/ and graphitic nitrogen in the carbon frameworks plays an essential role in the highly electrocatalytic activity for ORR. In this regard, carbon nitride (CN), a carbonaceous material that is enriched with a very high nitrogen content including both pyridinic and graphitic nitrogen moieties and that can be readily obtained through the pyrolysis of cyanamide, [9] melamine, [10] or ethylenediamine/carbon tetrachloride, [11] may serve as a potential metal-free catalyst for ORR. However, the low electrical conductivity (< 10 À2 S cm À1 ) of CN materials constitutes a major obstacle for their application in fuel cells given that the electron transport in a CN
[*] Dr.