Customized Patterning of Deep Nanowell Structures in Polymer Electrolyte Membranes for Highly Enhanced Fuel Cell Performances

Surface microstructuring of polymer electrolyte membranes (PEMs) has been considered as an effective strategy to extend the three-phase boundary in PEM fuel cells (PEMFCs). However, it is still unclear which parameters are the most critical for maximizing cell performance. In this study, in order to elucidate the correlation between the membrane surface topography and PEMFC performances, we employed solvent-assisted nanotransfer printing and plasma deep etching techniques, which allow independent control of structural parameters. This approach enables the formation of various catalyst–membrane interface structures with controlled pattern periods and aspect ratios. Our systematic customization reveals that nanowell patterned membranes partially filled with carbon-supported platinum (Pt/C) can significantly improve fuel cell performance, which is driven by both reducing kinetic resistance and mass transport resistance. In particular, the sample with a pattern period of 1200 nm and a well depth of 1100 nm exhibited the best performance, a current density of 1000 mA/cm 2 at a cell voltage of 0.6 V, and a maximum power density of 583 mW/cm 2 . These values are 53 and 41% higher than those with unpatterned membranes, respectively, at the same Pt loading.