Conductive Mechanism of Low-Pt-Coated Porous Transport Layers at Key Interfaces in Proton Exchange Membrane Water Electrolyzers.

Liu, Yun; Meng, Lingda; Ma, Yilin; Yang, Kaikai; Shi, Wenjuan; Li, Jing; Rao, Peng; Wang, Tianjiao et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Proton exchange membrane water electrolyzers (PEMWEs) are key for renewable hydrogen production, featuring two critical charge transport interfaces: porous transport layer/catalyst layer (PTL/CL) and PTL/flow field (PTL/FF). To study interface charge transport, three Pt-loaded PTL anodes were combined with a normal or low-loading membrane electrode. Normal loading: optimized Pt boosts catalyst use; low loading: thinnest coating removes PTL/CL passivation. Notably, at low loading and low current density (<0.3 A cm<sup>-2</sup>), when charge barriers exist at the PTL/CL interface, an uneven Pt coating fails to improve PTL/FF conductivity and instead introduces additional barriers─an effect that diminishes with optimized coating or increased current density. The charge barrier at the PTL/CL interface amplifies the negative effects at the PTL/FF interface; this effect can be mitigated by applying a uniform coating or increasing the current. These findings provide guidance for optimizing platinum-coated PTLs and for studying charge transport at the PTL/FF interface.