Boosting active site accessibility and alleviating mass transfer resistance for high-performance fuel cells

TY - JOUR

T1 - Boosting active site accessibility and alleviating mass transfer resistance for high-performance fuel cells

AU - Li, Jiaxin

AU - Sun, Caiting

AU - Fan, Haiyang

AU - Dong, Feilong

AU - Lv, Zunhang

AU - Liu, Rui

AU - Yang, Wenxiu

AU - Wang, Bo

N1 - Publisher Copyright: © The Author(s) 2025.

PY - 2025/8

Y1 - 2025/8

N2 - Precise engineering of single-atom catalysts (SACs) with hierarchical porous structures and optimized mass/charge transfer properties is crucial for advancing oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Herein, we present a novel molten salt-assisted pyrolysis strategy that employs a “dimensional reduction and pore creation” approach to exfoliate three-dimensional (3D)-metal–organic frameworks (MOFs) into three-dimensional porous carbon nanosheets doped with single-atom Fe, resulting in Fe SACs supported on hierarchical porous nitrogen-doped carbon (Fe SA@HPNC). The molten salt treatment simultaneously induces exfoliation and etching, resulting in a hierarchical porous structure with both micropores and mesopores, and a remarkably high specific surface area of 919.5 m2·g−1. The two-dimensional nanosheet structure enhances the anchoring of Fe by exposing more surface micropores, which reduces Fe being deeply buried in internal micropores and improves oxygen accessibility and mass/charge transfer efficiency. The Fe SA@HPNC demonstrates excellent ORR performance with a half-wave potential of 0.90 V and a kinetic current density of 19.9 mA·cm−2. When applied as the cathode in PEMFCs, the Fe SA@HPNC-based cell achieves a remarkable maximum power density of 900 mW·cm−2. Distribution of relaxation times analysis further reveals that the exfoliated catalyst exhibits enhanced ORR kinetics and reduced oxygen transport resistance.

AB - Precise engineering of single-atom catalysts (SACs) with hierarchical porous structures and optimized mass/charge transfer properties is crucial for advancing oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Herein, we present a novel molten salt-assisted pyrolysis strategy that employs a “dimensional reduction and pore creation” approach to exfoliate three-dimensional (3D)-metal–organic frameworks (MOFs) into three-dimensional porous carbon nanosheets doped with single-atom Fe, resulting in Fe SACs supported on hierarchical porous nitrogen-doped carbon (Fe SA@HPNC). The molten salt treatment simultaneously induces exfoliation and etching, resulting in a hierarchical porous structure with both micropores and mesopores, and a remarkably high specific surface area of 919.5 m2·g−1. The two-dimensional nanosheet structure enhances the anchoring of Fe by exposing more surface micropores, which reduces Fe being deeply buried in internal micropores and improves oxygen accessibility and mass/charge transfer efficiency. The Fe SA@HPNC demonstrates excellent ORR performance with a half-wave potential of 0.90 V and a kinetic current density of 19.9 mA·cm−2. When applied as the cathode in PEMFCs, the Fe SA@HPNC-based cell achieves a remarkable maximum power density of 900 mW·cm−2. Distribution of relaxation times analysis further reveals that the exfoliated catalyst exhibits enhanced ORR kinetics and reduced oxygen transport resistance.

KW - metal organic frameworks

KW - oxygen mass transfer

KW - oxygen reduction reaction

KW - proton exchange membrane fuel cell

KW - zinc air battery

UR - https://www.scopus.com/pages/publications/105015076118

U2 - 10.26599/NR.2025.94907654

DO - 10.26599/NR.2025.94907654

M3 - Article

AN - SCOPUS:105015076118

SN - 1998-0124

VL - 18

JO - Nano Research

JF - Nano Research

IS - 8

M1 - 94907654

ER -