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Scalable Self-Supported Graphene Foam for High-Performance Electrocatalytic Oxygen Evolution

Zhu, Yun-Pei, Ran, Jingrun, Qiao, Shi-Zhang
ACS applied materials & interfaces 2017 v.9 no.48 pp. 41980-41987
X-radiation, absorption, active sites, air, batteries, carbon fibers, cathodes, durability, electrochemistry, electron microscopy, electron transfer, energy, foams, graphene, longevity, nitrogen, oxygen, oxygen production, paper, surface area
Developing efficient electrocatalysts consisting of earth-abundant elements for oxygen evolution reaction (OER) is crucial for energy devices and technologies. Herein, we report self-supported highly porous nitrogen-doped graphene foam synthesized through the electrochemical expansion of carbon-fiber paper and subsequent nitrogen plasma treatment. A thorough characterization, such as electron microscopy and synchrotron-based near-edge X-ray absorption fine structure, indicates the well-developed porous structures featuring homogeneously doped nitrogen heteroatoms. These merits ensure enriched active sites, an enlarged active surface area, and improved mass/electron transport within the continuous graphene framework, thus leading to an outstanding capability toward electrocatalyzing OER in alkaline media, even competitive with the state-of-the-art noble-/transition-metal and nonmetal electrocatalysts reported to date, from the perspectives of the sharp onset potential, a small Tafel slope, and remarkable durability. Furthermore, a rechargeable Zn–air battery with this self-supported electrocatalyst directly used as the air cathode renders a low charge/discharge overpotential and considerable life span. The finding herein suggests that a rational methodology to synthesize graphene-based materials can significantly enhance the oxygen electrocatalysis, thereby promoting the overall performance of the energy-related system.