Evolution of gas diffusion layer structures for aligned Pt nanowire electrodes in PEMFC applications

Gas diffusion layer (GDL), consisting of a microporous layer (MPL) and a carbon fibre substrate, is one of the major components in proton exchange membrane fuel cells (PEMFCs). In gas diffusion electrodes (GDEs) with in-situ grown aligned Pt nanowire (NW) catalysts, the GDL can also provide an important function in controlling the growth and distribution of the Pt nanowires. In this work, a systematic investigation is conducted to evaluate the evolution of the GDL structure on the PtNW growth process to prepare GDEs. The influence mechanisms including carbon loading, carbon composition and polytetrafluoroethylene (PTFE) loading in the MPL and PTFE in the carbon fibre substrate on the electrode power performance are studied in detail. An optimum structure for MPL, 4 mg cm−2 carbon loading with an equal amount of carbon black (CB) and acetylene black (AB), plus 5% PTFE loading, is deserved. This GDL structure can provide suitable substrate coverage, reasonable surface nucleation sites and required hydrophobicity for the in-situ growth of PtNWs. The results indicate that the GDL features play a significant role in the growth and distribution of the obtained Pt nanowires to achieve high performance GDEs for PEMFC application.