Ultralow Pt-loading electrodes with 0.02 mg_Pt cm⁻²and 0.04 mg_Pt cm⁻² were prepared by electro hydrodynamic atomization (electrospray) of catalytic inks on carbon paper coated with a carbon micro-porous layer. MEAs of 25 cm² active area were manufactured with this type of electrodes [1-3] and tested in a single-cell equipped with segmented bipolar plates to show in operando the local current density distribution throughout the electrode surface. From hydrogen & air as feeding gases, tests under different pressures, relative humidity and gas flow rates were performed using the segmented cell [4,5]. Moreover, electrochemical impedance spectroscopy (EIS) analyses were accomplished to determine the ohmic and charge transfer resistances in each of the test conditions. The best performance was achieved for a MEA with an overall loading of 0.06 mg_Pt cm⁻² providing a platinum utilization of 3.8 kW g_Pt⁻¹ at 0.6 V and a maximum platinum utilization of 5.9 kW g_Pt⁻¹ when working at 70 ºC, 1.5 bar and stoichiometries of λ_H2=1.5 and λ_air= 2, At different test conditions, i.e. increasing the backpressure or the feeding flow rate, the cell behaviour improves significantly and maximum platinum utilizations of 9 kW g_Pt⁻¹ and 7 kW g_Pt⁻¹ were respectively reached. Additionally, short-term runs of about 100 hours of continuous operation were carried out to assess electrode durability.

References

[1] S. Martin, P. L. Garcia-Ybarra, J. L. Castillo, Method for the Uniform  Nanostructured Deposition of Catalytic Particles by Means of Electrospray,  WIPO Patent PCT Application No. WO 2013/144390 A1.

[2] S. Martin, P. L. Garcia-Ybarra, J. L. Castillo, Electrospray deposition of catalyst layers with ultra-low Pt loadings for PEM fuel cells cathodes, J. Power Sources, 195  (2010) 2443–2449.

[3] S. Martin, B. Martinez-Vazquez, P. L. Garcia-Ybarra, J. L. Castillo, Peak utilization of catalyst with ultra-low Pt loaded PEM fuel cell electrodes prepared by the electrospray method, J. Power Sources, 229 (2013) 179–184.

[4] B. Martinez-Vazquez, D. G. Sanchez, J. L. Castillo, K. A. Friedrich, P. L. Garcia-Ybarra, Scaling-up and characterization of ultralow-loading MEAs made up by electrospray, Int. J. Hydrogen Energy, 40 (2015) 5384-5389

[5] M. Schulze, E. Gülzow, S. Schönbauer, T. Knöri, R. Reissner, Segmented cells as tool for development of fuel cells and error prevention/prediagnostic in fuel cell stacks, J. Power Sources, 173  (2007) 19–27.