title: Electrochemical activation of commercial polyacrylonitrile-based carbon fiber for the oxygen reduction reaction.
abstract: Nitrogen (N)-doped carbon and its non-noble metal composite replacing platinum-based oxygen reduction reaction (ORR) electrocatalysts still have some fundamental problems that remain. Here the micron-sized commercial polyacrylonitrile-based carbon fiber (PAN-CF) electrode was modified using an electrochemical method, converting its inherent pyridinic-N into 2-pyridone (or 2-hydroxyl pyridine) functional group existing in three-dimensional active layers with remarkable ORR catalytic activity and stability. The carbon atom adjacent to the nitrogen and oxygen atoms is prone to act as an active site to efficiently catalyze a two-electron ORR process. However, after coordinating pyridone to the Cu(2+) ion, together with the electrochemical reaction, the chemical redox between Cu(+) and ORR intermediates synergistically tends towards a four-electron pathway in alkaline solution. In different medium, the complexation and dissociation can induce the charge transfer and reconstruction among proton, metal ion and pyridone functionalities, eventually leading to the changes of ORR performance.
authors.affiliation: Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, P. R. China. lazake@163.com.
authors.forename: Haibo
authors.initials: H
authors.lastname: Xu
authors.forename: Guangsen
authors.initials: G
authors.lastname: Xia
authors.forename: Haining
authors.initials: H
authors.lastname: Liu
authors.forename: Shuwei
authors.initials: S
authors.lastname: Xia
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Lu