Synthesis of Zr 2 ON 2 via a urea-glass route to modulate the bifunctional catalytic activity of NiFe layered double hydroxide in a rechargeable zinc-air battery.

The development of a highly efficient, stable, and low-cost bifunctional catalyst is imperative for facilitating the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, significant challenges are involved in extending its applications to rechargeable zinc-air batteries. This study presents a bifunctional catalyst, Zr ₂ ON ₂ @NiFe layered double hydroxide (LDH), that was developed by utilizing a urea-glass route for synthesizing the Zr ₂ ON ₂ precursor, followed by riveting NiFe LDH nanosheets using a hydrothermal method. Specifically, the vertical distribution of NiFe LDH on the Zr ₂ ON ₂ surface ensures the maximization of the number of accessible active sites and interfacial catalysis of NiFe LDH. Notably, Zr ₂ ON ₂ @NiFe LDH demonstrates ORR and OER bifunctional electrocatalytic behavior and high stability owing to its heterostructure and composition. Furthermore, a rechargeable zinc-air battery using a Zr ₂ ON ₂ @NiFe LDH electrocatalyst as the air cathode demonstrated a high peak power density (172 mW cm ^-2 ) and galvanostatic charge-discharge cycle stability (5 mA cm ^-2 over 443 h). Thus, this study presents an efficient and cost-effective strategy for the design of bifunctional electrocatalysts.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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