Elucidating the roles of the Fe-Nx active sites and pore characteristics on Fe-Pani-biomass-derived RGO as oxygen reduction catalysts in PEMFCs

• Published in: Materials research bulletin Vol. 145; p. 111526
• Main Authors: Sudarsono, Wulandhari, Wong, Wai Yin, Loh, Kee Shyuan, Kok, Kuan-Ying, Syarif, Nirwan, Abidin, Azim Fitri Zainul, Hamada, Ikutaro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2022
• Subjects: biomass RGO; Fe-Pani-RGO; noble-free; ORR activity; pore characteristics; biomass RGO; Fe-Pani-RGO; ORR activity; pore characteristics; noble-free
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2021.111526

•Variations in the Fe-Pani precursor to RGO biomass ratio led to different ORR performance•Highly accessible FeN2 and FeN4 hosted on micropores improved the ORR activity•Meso/macropores could increase mass transport and improve catalyst stability•A balance between micropores and meso/macropores is crucial to achieve high PEMFC performance Pyrolysed Fe-N-C catalysts are foreseen to be promising noble-free cathode catalysts for proton exchange membrane fuel cells. Nevertheless, efforts are required to overcome active site degradation, which is influenced by the meso/macroporous composition of the catalyst and support. Reduced graphene oxide from Sengon wood is seen as a potential support for Fe-polyaniline (Pani) catalysts due to its hierarchical porous structure that depends on N/C ratio. This work reveals that the Fe-N4 moiety serves as the active site, which is confirmed by XPS and first-principles calculations. Fe-Pani-RGO 2:0.2, with the highest content of Fe-N4 and specific surface area, results in the highest ORR activity with Eonset =0.84 V, E1/2 = 0.79 V, and JD = 5.5 mA/cm2. Although micropores are important for hosting the active sites that contribute to high ORR activity, in regard to single-cell performance, the role of meso‑/macropores is crucial for achieving higher overall performance. [Display omitted]