N‐Doped Carbon Electrocatalyst: Marked ORR Activity in Acidic Media without the Contribution from Metal Sites?
Fantao Kong, Xiangzhi Cui, Yifan Huang, Heliang Yao, Yafeng Chen, Han Tian, Ge Meng, Chang Chen, Ziwei Chang, Jianlin Shi
Abstract
Abstract Fe−N−C electrocatalysts have been demonstrated to be the most promising substitutes for benchmark Pt/C catalysts for the oxygen reduction reaction (ORR). Herein, we report that N‐doped carbon materials with trace amounts of iron (0–0.08 wt. %) show excellent ORR activity and durability comparable and even superior to those of Pt/C in both alkaline and acidic media without significant contribution by the metal sites. Such an N‐doped carbon (denoted as N‐HPCs) features a hollow and hierarchically porous architecture, and more importantly, a noncovalently bonded N‐deficient/N‐rich heterostructure providing the active sites for oxygen adsorption and activation owing to the efficient electron transfer between the layers. The primary Zn‐air battery using N‐HPCs as the cathode delivers a much higher power density of 158 mW cm −2 , and the maximum power density in the H 2 −O 2 fuel cell reaches 486 mW cm −2 , which is comparable to and even better than those using conventional Fe−N−C catalysts at cathodes.