Enhancement of oxygen reduction activity of nanoshell carbons by introducing nitrogen atoms from metal phthalocyanines

Nanoshell carbon is a type of catalytically grown nanocarbon with a hollow, round, shell-like structure, with a diameter in the range of approximately 20-50 rim It has been shown to possess the electrocatalytic activity for oxygen reduction reaction (ORR) and is also expected to be a non-Pt catalyst for polymer electrolyte fuel cells This paper reports the synergetic enhancement of the ORR activity of nanoshell carbons caused by the coexistence of nitrogen atoms. The nanoshell carbons were prepared by the carbonization of furan resin in the presence of acetylacetonates (AAs) and of phthalocyanines (Pcs), which contained Fe, Co, and Ni. The Pc-derived nanoshells (MP-T series; M=Co or Fe,T=carbonization temperature) showed higher ORR activities than the AA-derived nanoshells (MA-T series: M=Co or Fe. T=carbonization temperature) when the same metal elements were employed. An XPS study revealed that nitrogen species were introduced to the surface of the nanoshells when Pcs were used as the nanoshell-forming catalysts, and that no metal species remained on the nanoshells. Principally, the ORR activity of the carbons was governed by the presence of the nanoshells and further enhancement could be achieved by the introduction of nitrogen atoms 0 78 V of OCV and 0.21 W cm(-2) of the maximum power density were observed for a fuel cell whose MEA consisted of 3CoP1000 cathode and a commercial Pt/C anode, when it was operated at 80 degrees C under a pressurized condition of 0.35 MPa. (C) 2009 Elsevier Ltd. All rights reserved.