Lee, Jang Yeol Kim, Na Young Shin, Dong Yun Park, Hee-Young Lee, Sang-Soo Kwon, S. Joon Lim, Dong-Hee Bong, Ki Wan Son, Jeong Gon Kim, Jin Young 2024-01-20T02:02:40Z 2024-01-20T02:02:40Z 2021-09-01 2017-03 1388-0764 https://pubs.kist.re.kr/handle/201004/123011 Transition metals, such as iron (Fe)- or cobalt (Co)-based nanomaterials, are promising electrocatalysts for oxygen reduction reactions (ORR) in fuel cells due to their high theoretical activity and low cost. However, a major challenge to using these metals in place of precious metal catalysts for ORR is their low efficiency and poor stability, thus new concepts and strategies should be needed to address this issue. Here, we report a hybrid aciniform nanostructures of Fe nanofragments embedded in thin nitrogen (N)-doped graphene (Fe@N-G) layers via a heat treatment of graphene oxide-wrapped iron oxide (Fe2O3) microparticles with melamine. The heat treatment leads to transformation of Fe2O3 microparticles to nanosized zero-valent Fe fragments and formation of core-shell structures of Fe nanofragments and N-doped graphene layers. Thin N-doped graphene layers massively promote electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers ORR activity at the graphene surface. With the synergistic effect arising from the N-doped graphene and Fe nanoparticles with porous aciniform nanostructures, the Fe@N-G hybrid catalyst exhibits high catalytic activity, which was evidenced by high E-1/2 of 0.82 V, onset potential of 0.93 V, and limiting current density of 4.8 mA cm(-2) indicating 4-electron ORR, and even exceeds the catalytic stability of the commercial Pt catalyst. English SPRINGER Nitrogen-doped graphene-wrapped iron nanofragments for high-performance oxygen reduction electrocatalysts Article 10.1007/s11051-017-3793-y 1 JOURNAL OF NANOPARTICLE RESEARCH, v.19, no.3 JOURNAL OF NANOPARTICLE RESEARCH 19 3 N scie scopus 000395625400003 2-s2.0-85014884580 Chemistry, Multidisciplinary Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article INITIO MOLECULAR-DYNAMICS TOTAL-ENERGY CALCULATIONS PEM FUEL-CELL CARBON NANOTUBES METAL-CATALYSTS EFFICIENT OXIDE NANOPARTICLES COMPOSITE ALKALINE Oxygen reduction reaction Non-precious metal electrocatalyst Graphene Doping Catalyst nanomaterial