Electrochimica Acta 134 (2014) 49–54 Contents lists available at ScienceDirect Electrochimica Acta j ourna l ho me page: www.elsevier.com/locate/electacta Enhancement of electrochemical properties through high-temperature treatment of CNF grown on ACF support for PEMFC Sang-Sun Park a , Yukwon Jeon a , Taegon Kim b,c , Joo-Il Park c,∗ , Yong-Gun Shul a,∗ a Department of Chemical Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 120-749, Korea b Battery Development Team, Energy Business Division, Samsung SDI Co., Ltd., 508 Sungsung-dong, Cheonan, Chungcheongnam-do 330-300, Korea c Interdisciplinary Graduate School of Engineering Science, Kyushu University, Fukuoka 816-8580, Japan a r t i c l e i n f o Article history: Received 18 February 2014 Received in revised form 2 April 2014 Accepted 20 April 2014 Available online 30 April 2014 Keywords: CNF ACF PEMFC Durability Pt catalyst Accelerated Degradation Test a b s t r a c t In this study, a new type of carbon support materials for proton exchange membrane fuel cells (PEMFCs) was evaluated. Carbon nanofibers (CNFs) grown on activated carbon fibers (ACFs) were prepared through catalytic growth to yield CNF/ACF materials. CNFs were synthesized by using CH 4 with Ni catalysts dis- persed on ACFs. The as-prepared samples were characterized with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM images revealed a three-dimensional CNF network grown on the ACF surface. High-temperature treatment effectively reinforced the CNF/ACF structure and led to increased electrochemical performance and durability of Pt catalysts in PEMFC operations. The accelerated degradation test (ADT) was used for stability evaluations of Pt catalysts. The ECSA loss from heat-treated Pt/CNF/ACF at 900 ◦ C was calculated to be 39.1%, whereas the ECSA loss from the non-heat- treated Pt/CNF/ACF rose to 56.3%. The results suggest that the higher corrosion resistance of the carbon support could come from the higher degree of graphitization through high-temperature heat treatment of CNF/ACF. This unique structure of the CNF grown on ACF can supply effective anchor sites for the stabilization of Pt particles. As a result, the heat-treated CNF/ACF is expected to be a promising carbon support to improve the cell performances of PEMFCs. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Research into alternatives to conventional energy systems such as fuel cells is required to address global environmental concerns. Fuel cells generate electricity by converting chemical energy inher- ent to hydrogen combustion into electrical energy based on H 2 oxidation at the anode and O 2 reduction at the cathode, produc- ing only water as a by-product. Generally, platinum and its alloys are employed as anode and cathode catalytic materials in pro- ton exchange membrane fuel cells (PEMFC) [1,2]. Since increased catalytic activities result with an increase in the reactionary sur- face area of the catalyst, it follows that catalyst size should be reduced to effect an increase in their active surface. Pt or Pt alloys supported on electron-conductive carbon materials (Pt/C) have received particular focus as ideal catalyst species. [3–5] It has been generally recognized that Pt/C based catalysts are active and stable for such fuel-cell reactions that are particularly in the highly acidic ∗ Corresponding authors. Tel.: +82 2 2123 2758; fax: +82 2 312 6507. E-mail addresses: parkjoo9@asem.kyushu-u.ac.jp (J.-I. Park), shulyg@yonsei.ac.kr (Y.-G. Shul). atmosphere of the polymer electrolyte. Nevertheless, the limita- tion of Pt reserves and supplies prohibits the wide usage of PEMFCs. Accordingly, enhancing the catalytic activity of Pt is highly desired in fuel-cell applications to overcome these limitations. In general, such catalysts are supported on carbon substrates possessing high surface areas. The optimized distribution of metal particles on the carbon surface can reduce the loading of Pt cata- lyst for efficient fuel-cell operation. In addition to a high surface area, which may be obtained through high porosity, carbon mate- rials also have sufficient electrical conductivity. Moreover, carbon supports with controllable porosity (micro- to meso-porous struc- tures) should stimulate the faster diffusion of chemical species, as well as provide high accessibility to the catalyst and to monomeric units of the Nafion® ionomers employed in fuel cells [6,7]. The sta- bility of the carbon support as it relates to corrosion resistance of the fuel cell is also of great importance in the design of novel carbon substrates [8–11]. Recently, new carbon materials such as activated carbon fibers (ACFs) and carbon nanofibers (CNFs) have been introduced as cata- lyst supports due to their unique physical and chemical properties [12,13]. Since the report of carbon nanotubes (CNTs) by Iijima [14], nanoscale carbon materials have found use in mechanical, http://dx.doi.org/10.1016/j.electacta.2014.04.105 0013-4686/© 2014 Elsevier Ltd. All rights reserved.