Carboxylated carbonized polyaniline nanofibers as Pt-catalyst conducting support for proton exchange membrane fuel cell

Abstract Polyaniline based nanofibers (PANF) prepared via emulsion polymerization without auxiliary organic solvent are carbonized to become a 1D and nitrogen-containing electrocatalyst support for proton exchange membrane fuel cell. The carbonization can significantly increase the conductivity of PANF but also create hydrophobic surface, causing much less Pt-loading reduced by ethylene glycol. Carboxylic acid groups are subsequently grafted to the surface by refluxing in sulfuric and nitric acids, which allow carbonized PANF to be dispersed in the aqueous solution and profoundly increase the Pt-loading. Carboxylated carbonized PANF electrocatalyst support demonstrates better electrochemical activity that prepared from carbon black (Vulcan XC-72) in the cyclic voltaic and ORR testing. The single-cell performance illustrates a higher power and max current density for MEA made of carboxylated carbonized PANF than that of carbon black. Besides, the MEA experiences neither a serious power density loss at high current density (in the cathode) nor the accumulation of water product in the cathode of MEA.