Effects of Surface Properties and Microstructures of Carbon Nanofibers on Their Electrocatalytic Activity for Oxygen Reduction Reaction

Abstract

Two types of carbon nanofibers(CNFs),tubular CNFs(t-CNFs) and fish-bone CNFs(f-CNFs) were synthesized and the effects of surface properties of CNFs on their electrocatalytic activity for oxygen reduction reaction(ORR) in alkaline media were investigated.Oxygen- and nitrogen-containing functional groups were introduced onto the CNF surface by sonochemical oxidation in mixed acids(concentrated sulfuric acid and nitric acid) and ammonia,respectively.The ORR activities of the CNF catalyst were measured in an oxygen-saturated 0.1 mol/L KOH electrolyte solution by rotating disk electrode(RDE) technique.The RDE results show that the electrocatalytic activities of the two types of CNFs increase in the same sequence untreated CNFs oxygen-containing CNFs nitrogen-containing CNFs,while the f-CNFs-based catalysts have higher electrocatalytic activities for ORR than t-CNFs-based counterparts.The results indicate that both the surface properties and the microstructures of CNFs have effects on the electrocatalytic activity of CNFs for ORR,although the former may have a dominant effect.