On the water transport mechanism through the microporous layers of polymer electrolyte fuel cells probed directly by X-ray tomographic microscopy.

Product water transport the microporous layer (MPL) and gas diffusion layer (GDL) substrate during polymer electrolyte fuel cell (PEFC) operation was directly and quantitatively observed by X-ray tomographic microscopy (XTM). The liquid water distribution in two types of MPLs with different pore size distributions (PSDs) was characterized as a function of the inlet gas relative humidity (RH) and current density under humid operating conditions at 45 °C. During the first minute of PEFC operation, liquid water mainly accumulated at the catalyst layer (CL)/MPL interface and in the GDL substrate close to the flow fields.

Gas Diffusion Layers with Deterministic Structure for High Performance Polymer Electrolyte Fuel Cells.

Hydrogen-fed polymer electrolyte fuel cells (PEFCs) are promising electrochemical energy converters and a key technology for sustainable mobility and coupling energy sectors. Under operating conditions, water is produced by the oxygen reduction reaction. The gas diffusion layer (GDL) materials, interfacing the reaction sites and gas feed channels, play a key role in the water management.

Revealing Active Sites for Hydrogen Evolution at Pt and Pd Atomic Layers on Au Surfaces.

Identification of the most active surface sites is one of the key tasks in the development of new electrocatalytic materials. This is in many cases both time and resource consuming due to methodological difficulties of in situ detection of centers of this kind. In this work, we use the recently developed approach based on the analysis of the tunneling current noise recorded by electrochemical scanning tunneling microscopy (n-ECSTM) to compare the nature of the most active hydrogen evolution catalytic sites in a system consisting of sub-monolayers of platinum on a Au substrate to the one of palladium on Au.