Fig. 3: Platinum-related morphology analysis in the microtomed 3M ionomer–HSC–platinum catalyst layer.
From: Three-dimensional nanoimaging of fuel cell catalyst layers
a, Sub-volume and magnified 2D maps from the segmented reconstruction in Fig. 2 demonstrating the localization of platinum nanoparticles interior (pink) or exterior (green) to the porous carbon supports. Scale cube, 103 nm3; scale bar, 20 nm. b, Distribution of the platinum diameters as a function of their location. The cutoff at 1.5 nm accounts for the resolution limit. c, Comparison of platinum surface measurements from tomography and electrochemistry. As illustrated in the magnified slices (scale bar, 5 nm), the measurements from the tomographic reconstruction represent the fraction of the platinum surface in direct contact with the ionomer (connected surface), and the fraction of the platinum surface of all particles in contact with the ionomer (surface of connected particles). Electrochemical measurements are the ECSA and platinum utilization from CO stripping surface area measurements as a function of relative humidity in the membrane electrode assembly (MEA), scanned from 0.1–1.0 V at 10 mV s–1 and 80 °C. The grey dots represent the average of N = 2 measurements. Error bars represent the measurements error due to segmentation for tomography (see Methods) and the min–max values of N = 2 measurements for electrochemical data.
