Fe‐N‐C Oxygen Reduction Fuel Cell Catalyst Derived from Carbendazim: Synthesis, Structure, and Reactivity

Abstract

New non‐PGM catalysts from the family of Fe‐N‐C pyrolyzed materials are reported. They are synthesized using a templating silica powder with iron nitrate and carbendazim (CBDZ) precursors (sacrificial support method). The synthesis involves high temperature pyrolysis, followed by etching of the sacrificial support (silica) and obtaining a “self‐supported” open frame morphology catalyst. Both the temperature of heat treatment and Fe to CBDZ ratio play a crucial role in the final catalytic activity in oxygen reduction reaction (ORR). Prepared materials have extremely high durability in RDE tests, ending up with more than 94% of initial activity (by E1/2 value) after 10 000 cycles in an oxygen atmosphere, which is the result we report for the first time. Evaluation of these new M‐N‐C catalysts in a single membrane electrode assembly (MEA) has shown an exceptionally high open circuit voltage (OCV) of 1 V and the world's second best performance with no IR correction. MEA tests have shown high current density of 700 mA cm‐2 at 0.6 V and 120 mA cm‐2 at 0.8 V. In‐depth structure‐to‐property correlation presents an evidence that Fe‐Nx centers are the active sites playing a key role in oxygen reduction reaction.

Degradation by Hydrogen Peroxide of Metal-Nitrogen-Carbon Catalysts for Oxygen Reduction

“…3,5 While the concept of ORR catalysis by materials or molecules comprising Fe or Co, nitrogen and carbon elements is known since 1964, 7 breakthroughs in the ORR activity and fuel cell performance that were necessary to seriously consider Fe(Co)-N-C catalysts as potential substitutes to platinum in the acidic environment of PEMFCs were reported only after 2008. 2,[8][9][10][11][12][13][14] While major advances in the ORR activity and power density of PEMFC comprising Fe(Co)-N-C based cathodes have been reported, the next grand scientific challenges are i) improved understanding of the structure of the active sites and ii) improved understanding of the degradation mechanisms. Depending on the latter, mitigation approaches might be very different: i) system-based solutions to avoid the transient high-potential polarization during start-up and shutdown, ii) catalyst-based approaches in order to avoid the formation of H 2 O 2 during ORR or to endow the catalysts with a higher graphitic character, iii) novel cathode designs in order to stabilize its electrical, hydrophilic and diffusion properties.…”

CuCo2O4ORR/OER Bi-Functional Catalyst: Influence of Synthetic Approach on Performance

“…As it has been shown from our group, the sacrificial support method (SSM) is a powerful tool for the preparation of cathode materials, anode materials and CNTs. [17][18][19][20][21][22][23][24][25][26][27] High surface areas of the final catalyst are a result of removing the sacrificial support, which can be controlled by the selection of silica with different particle sizes and surface areas.XRD analyses of the four samples show that the CuCo 2 O 4 made by SSM was a phase-pure spinel (∼96 wt%), despite the usage of a significantly lower temperature and calcination duration during synthesis (Figure 1, bottom). This can be explained by homogeneous coverage of the precursors on the surface of mono-dispersed silica particles.…”

Resolving Challenges of Mass Transport in Non Pt-Group Metal Catalysts for Oxygen Reduction in Proton Exchange Membrane Fuel Cells

“…22 GDEs were constructed onsite at Pajarito Powder and subsequently provided to Northeastern University for Membrane Electrode Assembly (MEA) preparation and testing.…”

“…The first requires the pyrolysis of a ferrous iron salt and a nitrogen-containing charge-transfer salt followed by the etching of a silica template to form a metal-nitrogen-carbon structure. [21][22][23] The second strategy utilizes the formation of a metal-organic-framework (MOF), which, upon pyrolysis, forms a highly active catalyst towards ORR that remains devoid of any direct coordination of iron to nitrogen. 24 Both of these materials were shown to have very high ORR activity in acid media and subsequently in PEMFCs.…”