Polymerizable Ionic Liquid as Nitrogen-Doping Precursor for Co–N–C Catalyst with Enhanced Oxygen Reduction Activity

Abstract

The Co–N–C catalyst with higher nitrogen content was fabricated with a polymerizable ionic liquid (PIL) of hydrolyzed vinyl imidazolium dihydrogen phosphate ([HVim]H 2 PO 4 ) as N-doping precursor. The PIL was first prepared and then reacted with Co(NO 3 ) 2 ·6H 2 O. The N-doped Co-based catalyst was then obtained after carbonization process at 600 °C. The electrochemical characterization indicated that the electroactivity of catalyst prepared with PIL shows higher activity toward oxygen reduction reaction (ORR) than that of the sample prepared with non-IL precursor or nonpolymerizable IL under similar conditions. The ORR onset potential of the C 1 (PIL as precursor) was approximately 100 mV higher than the counterpart prepared with C 2 (non-IL precursor) or C 3 (nonpolymerizable IL precursor) in basic electrolyte. The XPS results demonstrated that C 1 contains higher nitrogen with more pyridinic and pyrrolic nitrogen groups, which was favorable for ORR.