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We have used pulsed lased deposition ͑PLD͒ of platinum onto uncatalyzed E-TEK gas-diffusion electrodes ͑GDE͒ to prepare very low loading electrodes for polymer electrolyte membrane fuel cells ͑PEMFCs͒. When tested at the anode side, the Pt PLD electrodes containing as little as 0.017 mg Pt/cm 2 perform as well as standard E-TEK electrodes that contain about twenty-five times more Pt (0.4 mg/cm 2 ). X-ray diffraction analysis and scanning electron micrographs of Pt PLD electrodes indicate that the deposits are made of 13 nm diam crystallites evenly dispersed at the surface of the GDE backing.It has been known for years that to become commercially viable, the cost of polymer electrolyte membrane fuel cells ͑PEMFCs͒ must be lowered. The amount of platinum catalyst must be reduced to the lowest possible level. The introduction of supported platinum on carbon blacks has already helped lower the platinum loadings of PEMFCs from several mg/cm 2 to about 0.4 mg/cm 2 . 1,2 Researchers at Los Alamos National Laboratories 3 were able to bring cathode platinum loading down to 0.12 mg/cm 2 with no detrimental effect on fuel cell performance. Even lower loading (0.05 mg/cm 2 ) electrodes were prepared at Texas A&M University showing results similar to electrodes with loading of 5 mg/cm 2 . 4 The previous studies, along with others, have focused on decreasing the amount of platinum supported on carbon blacks. Other deposition techniques have also been tried like electrodeposition of platinum thin films on the surface of electrodes. 5 Also, sputtering deposition techniques were used in an effort to improve the performance of PEMFCs or to further reduce platinum loading. 15 years ago, Srinivassan et al. 6-8 studied the effect of the localization of platinum on the reaction kinetics. In these studies, platinum was sputtered on top of standard electrodes made from platinum black with success in improving the overall fuel cell performance. This clearly showed the importance of having platinum located close to the membrane.More recently, sputtering deposition techniques were used to produce thin platinum films to replace platinum black as catalyst in PEMFCs. According to Hirano et al., 9 a cathode made from a sputtered layer of Pt, equivalent to a loading of 0.1 mg/cm 2 , can produce results similar to the E-TEK electrode with a loading of 0.4 mg/cm 2 . Cha and Lee 10 proposed a different approach, which consisted in multiple sputtering of 5 nm layers of platinum directly on the Nafion 115 membrane. Each layer was deposited after the membrane was brushed with a Nafion carbon isopropanol ink. The performance of their electrode was almost equivalent to the performance obtained using a standard electrode (0.4 mg/cm 2 ). The Pt loading of their electrodes was 0.043 mg/cm 2 , nearly ten times less than on standard electrodes. This proved that a deposition method, not based on supported platinum, can be used in PEMFCs and that it could even help to further reduce the platinum loading necessary to obtain good performance. Recently also, Hau...

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