Pt doped cerium oxide thin films with a nano-porous structure was prepared by reactive rf magnetron deposition on a fuel cell gas diffusion layer [1] coated with nitrogenated amorphous carbon films (CN_x) as an interlayer. We show that the structure and morphology of the cerium oxide-CN_x composites depend on the oxygen and nitrogen concentration in working gas used for catalyst deposition. Considerable plasma erosion of the carbonaceous interlayer accompanied by the formation of highly porous carbon/cerium oxide bilayer systems is reported. Oxygen plasma etching of the carbon interlayer occurring simultaneously with cerium oxide film growth is considered to be the driving force for the formation of cerium oxide film nanoporosity with large active surface.

Thin film techniques permits to grow the catalyst film characterized by highly dispersed platinum [2] showing high hydrogen oxidation activity and stability. These new materials may help to substantially reduce the demand for expensive noble-metals in proton exchange membrane fuel cell (PEMFC) catalytic applications.

We prepared 50 cm² MEAs with 6 μg Pt/cm² anode and 300 μg Pt/cm² cathode catalysts. The MEAs activity were measured in 10 cell hydrogen/air water cooled PEMFC stack, developed in our laboratory. Efficiency measurements performed at different pressures, temperatures, and hydrogen flow conditions were compared with performance of standard reference MEAs. We showed that MEAs made by assembling thin film Pt-CeO_x/CN_x anodes, containing 6 μg Pt per 1 cm² only, and reference cathodes can be used for fabrication of state of the art low Pt content PEMFC stacks delivering high specific power. It is shown that the almost Pt free anode technology represents promising solution for future fabrication of PEMFC stacks using Pt free cathodes under development.

Reference

[1] Fiala, R; Figueroba, A; Bruix, A; Vaclavu, M; Rednyk, A; Khalakhan, I; Vorokhta, M; Lavkova, J; Illas, F; Potin, V; Matolinova, I; Neyman, KM; Matolin, V, High efficiency of Pt²⁺- CeO₂ novel thin film catalyst as anode for proton exchange membrane fuel cells, Appl. Catal. B-Environ., 197 : 262–270, 2016.

[2] Dvorak, F; Camellone, MF; Tovt, A; Tran, N-D; Negreiros, FR; Vorokhta, M; Skala, T; Matolinova, I; Myslivecek, J; Matolin, V; Fabris, S, Creating single-atom Pt-ceria catalysts by surface step decoration, Nat. Commun., 7 (Feb): Art. No. 10801, 2016.