Journal of Power Sources 162 (2006) 186–191 Short communication Using Pt sols to prepare low Pt-loading electrodes for polymer electrolyte fuel cells Maksudur R. Khan a,b,1 , Shawn D. Lin a,b,∗ a The Fuel Cell Center, Yuan Ze University, Chung-Li, Taiwan 320, ROC b Department of Chemical Engineering and Material Science, Yuan Ze University, Chung-Li, Taiwan 320, ROC Received 29 March 2006; accepted 17 July 2006 Available online 20 September 2006 Abstract Novel platinum electrodes with controllable platinum loadings are prepared by direct deposition of platinum sols prepared with citrate and methanol. No extra treatment is needed except the evaporation of solvent. The platinum particles maintain a size similar to that of the original sols, as indicated by XRD data. The platinum-deposited membrane shows high specific activity and comparable single-cell performance with electrodes prepared from Pt/C catalysts. This electrode preparation method has the advantages of easy preparation and a good control for lowering the platinum-loading. © 2006 Elsevier B.V. All rights reserved. Keywords: Pt sols; Pt loading; Electrodes; Fuel cells 1. Introduction Polymer electrolyte fuel cells (PEFCs) have emerged as can- didates for transportation, portable and stationary power systems due to their good energy conversion efficiency and potentially high power density [1,2]. To make PEFCs a commercial real- ity, much development work is focusing on improving polymer electrolytes, electrocatalysts and electrode materials [3,4]. In particular, cost is a very important issue. The material cost of the polymer electrolyte membrane can be reduced either by a growth in the market size and/or by the use of less expensive non-fluoro polymers. The other key to reducing the material cost of PEFCs is to decrease the amount of Pt without sacrificing performance. This can be achieved by maximizing the utilization of Pt cata- lysts via optimizing the three-phase interface at every Pt active site in the electrodes [5]. A major progress in enhancing perfor- mance and reducing Pt loading has been achieved during the past few decades by using Pt/C instead of Pt black as the electrocata- lyst, and by impregnation of a proton conductor (Nafion) into the ∗ Corresponding author. Tel.: +886 3 4638800x2554; fax: +886 3 4559373. E-mail address: sdlin@saturn.yzu.edu.tw (S.D. Lin). 1 Current address: Department of Chemical Engineering and Polymer Sci- ence, Shah Jalal University of Science and Technology, Sylhet 3114, Bangladesh. catalyst layer of the gas-diffusion electrode [6–9]. Nevertheless, the Pt loading and its material cost are still too high for practical use. Catalyst sites not in direct contact with both the ionomer and the electron collector are non-reacting and cause poor Pt utilization [10]. Methods like tuning the Nafion loading in the catalyst layer [11,12] have been proposed to promote the interfa- cial contact between Pt particles and ionomers in order to boost utilization. Another approach tries to deposit Pt on the Nafion surface. Such preparation by a chemical reduction route [13,14] results, however, in poor catalyst utilization due to platiniza- tion of the membrane channels. O’Hayre et al. [15] deposited Pt on to a Nafion117 membrane by sputtering and a loading of 0.04 mg Pt cm -2 was found to given a performance compa- rable with a commercial MEA with a 0.4 mg Pt cm -2 loading. The disadvantages of this sputtering method are that the proce- dure is tedious and that the performance of the fuel cell changes dramatically with Pt loading. Pt nanoparticles of controlled size and shape can be prepared by wet-chemistry methods among which the sol–gel method is widely practiced in the presence of stabilizers [16–21]. The use of such Pt nanoparticles for PEFCs has not been exten- sively investigated. The presence of a polymer stabilizer of high molecular weight is likely to be detrimental to the cat- alytic properties of Pt nanoparticles and is therefore undesirable. The removal of polymer stabilizing agents require oxidation or 0378-7753/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2006.07.065