A Co-N/C hollow-sphere electrocatalyst derived from a metanilic CoAl layered double hydroxide for the oxygen reduction reaction, and its active sites in various pH media  

作　　者：Jun Wang Liqun Li Xu Chen Yanluo Lu Wensheng Yang Xue Duan 

机构地区：[1]State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China

出　　处：《Nano Research》2017年第7期2508-2518,共11页纳米研究（英文版）

基　　金：This research was supported by the National Basic Research Program of China （No. 2014CB932103）, National Natural Science Foundation of China （Nos. 51272020, 21236003, and U1407118）, Beijing Engineering Center for Hierarchical catalysts and Fundamental Research Funds for the Central Universities （No. YS1406）.

摘　　要：Transition-metal-coordinating nitrogen-doped carbon catalysts （M-N/C, M = Co, Fe, Mn, Ni, etc.） are considered one of the most promising nonprecious-metal electrocatalysts for the oxygen reduction reaction （ORR）. However, they suffer from low ORR catalytic activity, and their active sites have not been fully identified. Herein, we report the synthesis of a porous Co-N/C hollow-sphere electrocatalyst by carbonization of metanilic anions between the layers of a Co-A1 layered double hydroxide. The as-prepared Co-N/C catalyst exhibited excellent ORR catalytic activity with a high half-wave potential and a large diffusion-limited current in alkaline and neutral solutions. The performance of the catalyst was comparable to those of commercial Pt/C electrocatalysts. Through investigating the effects of mask ions （SCN- and F-） on the ORR activity of the Co-N/C catalyst, and comparing the ORR activity before and after the destruction of Co-Nx sites in different pH media, we concluded that the Co-Nx sites act directly as the ORR active sites in acidic and neutral solutions, but have a negligible effect on the ORR activity in alkaline conditions.Transition-metal-coordinating nitrogen-doped carbon catalysts （M-N/C, M = Co, Fe, Mn, Ni, etc.） are considered one of the most promising nonprecious-metal electrocatalysts for the oxygen reduction reaction （ORR）. However, they suffer from low ORR catalytic activity, and their active sites have not been fully identified. Herein, we report the synthesis of a porous Co-N/C hollow-sphere electrocatalyst by carbonization of metanilic anions between the layers of a Co-A1 layered double hydroxide. The as-prepared Co-N/C catalyst exhibited excellent ORR catalytic activity with a high half-wave potential and a large diffusion-limited current in alkaline and neutral solutions. The performance of the catalyst was comparable to those of commercial Pt/C electrocatalysts. Through investigating the effects of mask ions （SCN- and F-） on the ORR activity of the Co-N/C catalyst, and comparing the ORR activity before and after the destruction of Co-Nx sites in different pH media, we concluded that the Co-Nx sites act directly as the ORR active sites in acidic and neutral solutions, but have a negligible effect on the ORR activity in alkaline conditions.

关 键 词：confined space hollow carbon sphere hierarchical pore structure ELECTROCATALYSTS oxygen reduction reaction 

分 类 号：TQ351.471[化学工程] TQ314