Issue 24, 2023

Organic ligand-facilitated in situ exsolution of CoFe alloys over Ba0.5Sr0.5Co0.8Fe0.2O3−δ perovskite toward enhanced oxygen electrocatalysis for rechargeable Zn-air batteries

Abstract

Cobalt-based perovskites are promising electrocatalysts for the oxygen evolution/reduction reaction (OER/ORR), while their surface modification with nanoparticles may further improve the performance. In the past, in situ exsolution of a metal (alloy) over a perovskite surface promoted by a H2 atmosphere has been widely applied in developing nanoparticle modified anode materials for solid oxide fuel cells. However, it is a big challenge to apply this strategy for synthesizing cobalt-rich perovskite oxides for oxygen electrocatalysis due to their poor phase stability under a highly reducing atmosphere. Here, we report another strategy of organic ligand-facilitated in situ exsolution under a N2 atmosphere for developing CoFe nanoalloys over Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) perovskite as an air electrode for zinc-air batteries (ZABs). The BSCF–CoFe interface, newly generated oxygen vacancies and Co–N–C porous networks provide conduction pathways for oxygen ions and electrons, leading to the enhanced electrochemical bi-functional performance. BSCF/CoFe offers OER activity, while Co–N–C and CoFe contribute to the ORR activity. Interestingly, the exsolved CoFe alloy also considerably promotes the ORR selectivity, leading to a 4e pathway. Consequently, ZABs integrated with the bi-functional electrocatalyst exhibit a favourable potential gap of 0.835 V at a discharge/charge current density of 5 mA cm−2, and the cell operates stably without obvious degradation for over 250 h.

Graphical abstract: Organic ligand-facilitated in situ exsolution of CoFe alloys over Ba0.5Sr0.5Co0.8Fe0.2O3−δ perovskite toward enhanced oxygen electrocatalysis for rechargeable Zn-air batteries

Supplementary files

Article information

Article type
Paper
Submitted
08 Sep 2022
Accepted
07 Nov 2022
First published
11 Nov 2022

J. Mater. Chem. A, 2023,11, 12856-12865

Organic ligand-facilitated in situ exsolution of CoFe alloys over Ba0.5Sr0.5Co0.8Fe0.2O3−δ perovskite toward enhanced oxygen electrocatalysis for rechargeable Zn-air batteries

Y. Arafat, M. R. Azhar, Y. Zhong, R. O'Hayre, M. O. Tadé and Z. Shao, J. Mater. Chem. A, 2023, 11, 12856 DOI: 10.1039/D2TA07104E

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