Elastic carbon nanotube aerogels with unidirectional alignment as electrocatalyst support for high performance ultralow Pt-loaded fuel cell electrodes

Abstract

Carbon support structures based on elastic carbon nanotube (CNT) aerogels are designed as efficient ultralow Pt-loaded catalyst layers for proton exchange membrane fuel cells (PEMFCs). The CNT aerogels consist of elastic self-supporting frameworks with controlled linear packing density and alignment. Among different morphologies, the horizontally aligned structure exhibits 180 % higher tensile strength, 13.7 % greater porosity, and enhanced connectivity and crystallinity. This optimized configuration enables efficient electron and mass transport pathways, resulting in superior PEMFC performance at ultralow Pt loadings. A maximum power density of ∼0.5 W cm−2 is achieved at 0.1 mgPt cm−2 when the horizontally aligned CNT aerogel is employed as a cathode, significantly outperforming both conventional carbon black and randomly aligned CNT electrodes. The performance enhancement is attributed to improved electron transport and oxygen gain facilitated by the thin two-dimensional, densely aligned CNT bundles.