J.W. Lee, J. Zhang, Y. Kim, A. Byeon
Korea Advanced Institute of Science and Technology, Korea
pp. 45 - 48
Keywords: carbon-metal nanocomposites, electrocatalysis, fuel cell
The polymer electrolyte fuel cells(PEFCs) have demonstrated one of promising devices to convert chemical energy of fuels with high energy efficiency, high power density, and low environment impact. Despite wide applications in many areas, the large-scale commercialization of PEFCs is difficult because of expensive platinum-based electrocatalysts for oxygen reduction reaction (ORR) at cathode. There have been numerous efforts to developing substitution of platinum-based electrocatalysts and this work introduces boron-doped carbon/iron nanocomposites (Fe/B/C) as oxygen reduction electrocatalysts. It was synthesized through the reduction of CO2 by NaBH4 with the Fe precursor at 500℃ and atmospheric pressure. Furthermore we did heat treatment to the resulted Fe/B/C at 850℃, 1050℃ (sample named as FeBC050, FeBC850 and FeBC105). Fe/B/C composites has a core@shell structure, in which the iron-containing nanoparticles are confined within onion-like graphitic carbon shells. Electrochemical analyses in cyclic voltammetry (CV) and rotating disk electrode (RDE) showed Fe/B/C composites enhanced ORR activity and especially FeBC105 present better performance. Through XRD analyses, XPS, SEM and HRTEM observations, the thermal annealing is proved to be the reason for this better performance that changes the surface state and more active sites are generated by both the reduction of γ-Fe2O3 and the decomposition of B4C species.