A Rechargeable Urea-Assisted Zn-Air Battery with High Energy Efficiency and Fast-Charging Enabled by Engineering High-Energy Interfacial Structures.

ABSTRACT

Electrochemical urea oxidation reaction (UOR) offers a promising alternative to the oxygen evolution reaction (OER) in clean energy conversion and storage systems. Nickel-based catalysts are highly regarded as promising electrocatalysts for the UOR. However, their effectiveness is significantly hindered by the unavoidable self-oxidation reaction of nickel species during UOR. To address this challenge, we proposed an interface chemistry modulation strategy to boost UOR kinetics by creating a high-energy interfacial heterostructure. This heterostructure features the incorporation of Ag at the CoOOH@NiOOH heterojunction interface. Strong interactions significantly promote the electron exchanges in the heterointerface between the -OH and -O. Consequently, the improved electron delocalization led to the formation of stronger bonds between Co sites and urea CO(NH2)2, promoting a preference for urea to occupy Co active sites over OH*. The resulting catalyst, Ag-CoOOH@NiOOH, affords an ultrahigh UOR activity with a low potential of 1.33 V at 100 mA cm-2. The fabricated catalyst exhibits a mass activity exceeding that of initial cobalt oxyhydroxide by over 11.9 times. The rechargeable urea-assisted zinc-air batteries (ZABs) achieves a record-breaking energy efficiency of 74.56% at 1 mA cm-2, remarkable durability (1000 hours at even a current density of 50 mA cm-2), and quick charge performances.