Open AccessStability of Atomically Dispersed Fe–N–C ORR Catalyst in Polymer Electrolyte Fuel Cell Environment
Author(s) -
Rajesh Ahluwalia,
X. Wang,
Luigi Osmieri,
Junhui Peng,
C. Firat Cetinbas,
J. Park,
Deborah J. Myers,
Hyun Kyu Chung,
K.C. Neyerlin
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abe34c
Subject(s) - catalysis , platinum , electrolyte , durability , chemistry , polarization (electrochemistry) , metal , fuel cells , transition metal , materials science , chemical engineering , electrode , composite material , organic chemistry , engineering
We have investigated the durability of a platinum group metal (PGM-)free Fe–N–C catalyst in which the Fe sites are atomically dispersed (AD), and found it to be quite stable in standard accelerated stress test (AST) cycles normally used for low-PGM catalysts: a square wave with 0.6 V lower potential limit (LPL)—0.95 V upper potential limit (UPL) with 3-s holds at UPL and LPL in H 2 /N 2 , at 1.5 atm, 80 °C and 100% RH. Considering the metrics normally employed to characterize the durability of the low-PGM catalysts after 30,000 AST cycles, this PGM-free catalyst lost <50% catalyst activity, <50% H 2 /air performance at 0.8 V, and 40 mV at 1.5 A cm −2 . However, it is less stable in H 2 /air, losing ∼50% catalyst activity after just 7.5 h of polarization measurements (load cycles). In combined cycles, the majority of the loss in catalyst activity occurred during the load cycles in H 2 /air rather than AST cycles in H 2 /N 2 . We have concluded that, unlike low-PGM catalysts that lose electrochemically active surface area (ECSA) through potential cycling-induced processes, (AD)Fe–N–C catalysts degrade by processes associated with the presence of oxygen.