Fuel cell performances at optimized Nafion and Ru85Se15 loadings in cathode catalyst layer

The citric acid treated carbon supported Ru85Se15 catalysts are synthesized by microwave assisted polyol method at the optimal solution pH = 7. The catalyst coated membrane method with ultrasonic-spray technique is employed to prepare electrodes without hot press step. The cell performances with different Nafion contents and Ru loads in the cathode catalyst layer are systematically examined in both H2/air and H2/O2 fuel cells at 65 °C under ambient pressure. The surface morphologies of membrane electrode assemblies and the interfacial characteristics of single cells are studied using scanning electron microscopy and electrochemical impedance spectroscopy, respectively. The Nafion content is optimized to be 33% when the catalyst loadings are lower than 0.8 and 0.6 mg Ru cm−2 in the H2/air and H2/O2 fuel cells, respectively, but reduced to 20% at the higher Ru loads. The maximum peak power densities of 190 mW cm−2 at 620 mA cm−2 and 400 mW cm−2 at 1430 mA cm−2 are achieved in the H2/air and H2/O2 fuel cells, respectively, with 0.27 mg Ru cm−2 and 33% Nafion. The best catalyst utilizations are obtained at 0.14 mg Ru cm−2 with 33% Nafion, resulting in the maximum peak power densities per unit mass Ru of 917 and 2460 mW mg−1 in the H2/air and H2/O2 fuel cells, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The electrodes were prepared by ultrasonic-sprayed membrane without hot press. ► The effects of Nafion contents and catalyst loads on cell performance were studied. ► The Nafion and Ru loads were optimized for both H2/air and H2/O2 single cells. ► The mass peak power was as high as 2.46 W (mg Ru)−1 with 0.14 mg Ru cm−2. ► The maximum power density was 400 mW cm−2 with 0.27 mg Ru cm−2 and 33% Nafion.