Unexpected Performance of Inkjet‐Printed Membrane Electrode Assemblies for Proton Exchange Membrane Fuel Cells

The effect of the deposition substrate on the performance of inkjet‐printed membrane electrode assemblies (MEAs) is investigated. MEAs are fabricated from inkjet‐printed catalyst‐coated membranes (CCMs), gas diffusion electrodes (GDEs), and a bilateral sandwich of a CCM and a GDE. All MEAs are tested in proton exchange membrane fuel cells (PEMFCs). When a hot‐pressing step is included in the MEA construction, the power density achieved with the GDE‐based MEA is 1.067 W cm −2 , exceeding that achieved with the CCM‐based MEA (0.579 W cm −2 ), and the bilateral sandwich MEA (0.792 W cm −2 ). The origin of the superior performance of the inkjet‐printed GDE‐based MEAs is investigated through electrochemical impedance spectroscopy and analysis of the microstructure of the printed membranes and electrodes. Atomic force microscopy and energy dispersive X‐ray spectroscopy suggest that the greater surface and interfacial areas of the GDE‐printed catalyst layer may drive the unexpectedly high performance of the GDE‐based MEA as compared with its CCM and bilateral sandwich counterparts. These results provide new insights into the connections between the substrate, inkjet‐printed catalyst layer microstructure, and catalyst utilization.