posted on 2022-01-26, 14:44authored byYoung
Jun Lee, Hee-Eun Kim, Hyunkyu Oh, Hongseok Yun, Joonho Lee, Sangyong Shin, Hyunjoo Lee, Bumjoon J. Kim
Two-dimensional
sheet-like mesoporous carbon particles are promising
for maximizing the number of active sites and the mass transport efficiency
of proton exchange membrane fuel cells (PEMFCs). Herein, we develop
a series of lens-shaped mesoporous carbon (LMC) particles with perpendicularly
oriented channels (diameter = 60 nm) and aspect ratios (ARs) varying
from 2.1 to 6.2 and apply them for the fabrication of highly efficient
PEMFCs. The membrane emulsification affords uniform-sized, lens-shaped
block copolymer particles, which are successfully converted into the
LMC particles with well-ordered vertical channels through hyper-cross-linking
and carbonization steps. Then, an ultralow amount (1 wt %) of platinum
(Pt) is loaded into the particles. The LMC particles with higher ARs
are packed with a higher density in the cathode and are better aligned
on the cathode surface compared to the LMC particles with lower ARs.
Thus, the well-ordered channels in the particles facilitate the mass
transport of the reactants and products, significantly increasing
the PEMFC performance. For example, the LMC particles with the AR
of 6.2 show the highest initial single cell performance of 1135 mW
cm–2, and the cell exhibits high durability with
1039 mW cm–2 even after 30 000 cycles. This
cell performance surpasses that of commercial Pt/C catalysts, even
at 1/20 of the Pt loading.