[Fe(CN)6] vacancy-boosting oxygen evolution activity of Co-based Prussian blue analogues for hybrid sodium-air battery

Kang, Yao, Wang, Shuo, San Hui, Kwan, Li, Hai-Feng, Liang, Feng, Wu, Xin-Lin, Zhang, Qiuju, Zhou, Wei, Chen, Liang, Chen, Fuming and Hui, Kwun Nam (2021) [Fe(CN)6] vacancy-boosting oxygen evolution activity of Co-based Prussian blue analogues for hybrid sodium-air battery. Materials Today Energy, 20. ISSN 2468-6069

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Abstract

Prussian blue analogues (PBAs) have emerged as efficient catalysts for oxygen evolution reaction (OER) due to their porous structure with well-dispersed active sites. However, Co-based PBA (Co-PBA) electrocatalysts are characterized by moderate OER kinetics. In this study, we developed a facile high-yield strategy to fabricate defective Co-PBA (D-Co-PBA) with [Fe(CN)6] vacancies and exposed Co (III) active sites by post-oxidation treatment of the pristine Co-PBA with aqueous H2O2. Rietveld refinement results show that the lattice parameter (a) and unit-cell volume (V) of D-Co-PBA are smaller than those of the pristine Co-PBA, thereby confirming the generation of [Fe(CN)6] vacancies. Density functional theory calculations reveal that the [Fe(CN)6] vacancy can effectively regulate the electronic structure of D-Co-PBA; this condition reduces the reaction barrier of the rate-determining step toward OER. In OER, the D-Co-PBA catalyst achieves a lower overpotential of 400 mV at a current density of 10 mA cm−2, which is superior to that of Ir/C (430 mV) and Co-PBA (450 mV). A hybrid sodium-air battery assembled with Pt/C and D-Co-PBA catalysts displays a discharge voltage of 2.75 V, an ultralow charging–discharging gap of 0.15 V, and a round-trip efficiency of 94.83% on the 1000th cycle at the current density of 0.01 mA cm-2. This study is highly promising for large-scale production of affordable and effective PBA-based materials with desirable OER activity for metal-air batteries and water-alkali electrolyzers, thus helping achieve the goal of sustainability.

Item Type: Article
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Depositing User: LivePure Connector
Date Deposited: 28 Oct 2020 01:14
Last Modified: 21 Jul 2021 01:40
URI: https://ueaeprints.uea.ac.uk/id/eprint/77455
DOI: 10.1016/j.mtener.2020.100572

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