Ultrathin Nanotube Structure for Mass-Efficient and Durable Oxygen Reduction Reaction Catalysts in PEM Fuel Cells

It remains a challenge for platinum-based oxygen reduction
reaction
catalysts to simultaneously possess high mass activity and high durability
in proton-exchange-membrane fuel cells. Herein, we report ultrathin
holey nanotube (UHT)-structured Pt–M (M = Ni, Co) alloy catalysts
that achieve unprecedented comprehensive performance. The nanotubes
have ultrathin walls of 2–3 nm and construct self-supporting
network-like catalyst layers with thicknesses of less than 1 μm,
which have efficient mass transfer and 100% surface exposure, thus
enabling high utilization of Pt atoms. Combined with the high intrinsic
activity produced by the alloying effect, the catalysts achieve high
mass activity. Moreover, the nanotube structure not only avoids the
agglomeration problem of nanoparticles, but the low curvature of the
tube wall also gives UHT a low surface energy (less than 1/3 of that
of the same size nanoparticle), so UHT is more resistant to the Ostwald
ripening and is stable. For the first time, the U.S. DOE mass activity
target and dual durability targets for load and start–stop
cycles are achieved on one catalyst. This study provides an effective
structural strategy for the preparation of electrocatalysts with high
atomic efficiency and excellent durability.