Physica B 323 (2002) 124–126 Preparation of fine platinum catalyst supported on single-wall carbon nanohorns for fuel cell application T. Yoshitake a, *, Y. Shimakawa a , S. Kuroshima a , H. Kimura a , T. Ichihashi a , Y. Kubo a , D. Kasuya d , K. Takahashi c , F. Kokai c , M. Yudasaka b , S. Iijima a,b,d a Fundamental Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501, Japan b Japan Science and Technology Corporation, 34 Miyukigaoka, Tsukuba 305-8501, Japan c Laser Research Center, Institute of Research and Innovation, 1201 Takada, Kashiwa, Chiba 277-0861, Japan d Department of Physics, Meijo University, 1501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan Abstract Platinum catalyst was supported on single-wall carbon nanohorns (SWNHs) to demonstrate the suitability of SWNH’s application to the electrodes of polymer–electrolyte fuel cells. The Pt particles were homogeneously dispersed on the SWNHs, and their particle size was about 2nm. This size was less than half of that supported on conventional carbon black. A fuel cell using the SWNHs had a larger current density than one using the carbon black. r 2002 Elsevier Science B.V. All rights reserved. PACS: 61.46.+w; 61.82.Rx; 73.90.+f Keywords: Single-wall carbon nanohorn; Pt; Catalyst; Fuel cell 1. Introduction The performance of a membrane electrode assembly for polymer–electrolyte fuel cells (PEFCs) greatly depends on the surface area of the platinum (Pt) catalyst particles supported on the carbon black electrodes. A finer Pt catalyst gives better performance because of its higher specific surface area. It has been reported that Pt particle size depends on the type of carbon black [1]. Single-wall carbon nanohorns (SWNHs) are a new type of carbon material having a horn-shaped sheath of single-wall graphitic sheets, and they associate with each other to form a ‘Dahlia- flower’-like aggregate [2]. This characteristic shape of the SWNHs should be able to support fine particles of Pt catalyst. In this work, we report on the support of Pt catalyst on SWNHs and the performance of fuel cells using SWNH electrodes. 2. Experimental The SWNHs were prepared by CO 2 laser ablation [1]. The Pt catalyst was supported on theSWNHsbyusingacolloidalmethod.NaHSO 3 and H 2 O 2 were added to an H 2 PtCl 6 solution to form Pt oxide colloids. The SWNHs powder was *Corresponding author. Tel.: +0298-50-1184; fax: +0298- 56-6137. E-mail address: t-yoshitake@cd.jp.nec.com (T. Yoshitake). 0921-4526/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0921-4526(02)00871-2