Bifunctionally active and durable hierarchically porous transition metal-based hybrid electrocatalyst for rechargeable metal-air batteries
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Date
2018-12-30
Authors
Seo, Min Ho
Park, Moon Gyu
Lee, Dong Un
Wang, Xiaolei
Ahn, Wook
Noh, Seung Hyo
Choi, Sung Mook
Cano, Zachary P.
Han, Byungchan
Chen, Zhongwei
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
In this work, we show an effective strategy combining experimental and computational methods to explore and clarify rational design approaches utilizing transition metals for enhanced electrocatalysis of oxygen reactions. We report a bifunctional electrocatalyst synthesized by a chemical deposition of palladium (Pd) nanoparticles on three-dimensionally ordered mesoporous cobalt oxide (Pd@3DOM-Co3O4) demonstrating extreme stability and activity towards electrocatalytic oxygen reduction and evolution reactions (ORR and OER). Pd@3DOM-Co3O4 exhibits a significantly positive-shifted ORR half-wave potential of 0.88 V (vs. RHE) and a higher OER current density of 41.3 mA cm−2 measured at 2.0 V (vs. RHE) relative to non-deposited 3DOM-Co3O4. Moreover, in terms of durability, Pd@3DOM-Co3O4 demonstrates a negligible half-wave potential loss with 99.5% retention during ORR and a high current density retention of 96.4% during OER after 1000 cycles of accelerated degradation testing (ADT). Ab-initio computational simulation of the oxygen reactions reveals that the modification of the electronic structure by combining Pd and Co3O4 lowers the Pd d-band center and enhances the electron abundance at the Fermi level, resulting in improved kinetics and conductivity. Furthermore, it is elucidated that the enhanced electrochemical stability is attributed to an elevated carbon corrosion potential (Ucorr,C) for the Pd@3DOM-Co3O4 surface and an increased dissolution potential (Udiss) of Pd nanoparticles. Meanwhile, synergistic improvements in the bifunctional activity resulting from the combination of Pd and 3DOM-Co3O4 were confirmed by both electrochemical and physical characterization methods, which highlights the practical viability of Pd@3DOM-Co3O4 as an efficient bifunctional catalyst for rechargeable metal-air batteries.
Description
The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.apcatb.2018.06.006 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/
Keywords
3-dimensionally ordered mesoporous structure, Bifunctional electrocatalysts, Density functional theory, Oxygen electrocatalytic reactions, Rechargeable metal-air battery