Neutral aqueous zinc–air batteries (ZABs) are an emerging type of energy devices with substantially elongated lifetime and improved recyclability compared to conventional alkaline ZABs. However, their development is impeded by the lack of robust bifunctional catalyst at the air-electrode for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). We start with an example of NiFe2O4/FeNi2S4 heterostructured nanosheets (HNSs) to highlight the important of using hetero-interface to promote the OER and ORR catalysis, therefore enabling neutral rechargeable ZABs. Associated with the formation of abundant oxide/sulfide interfaces over NiFe2O4/FeNi2S4 HNSs’ surfaces, the catalyst’s oxygen binding energy can be effectively tuned to enhance the OER and ORR activities, as revealed by the density functional theory calculations. In 0.2 M phosphate buffer solution, the optimized NiFe2O4/FeNi2S4 HNSs present an excellent oxygen electrocatalytic activity and stability, with much lower OER and ORR overpotentials than single-component FeNi2S4 or NiFe2O4 and with negligible performance decay in accelerated durability testing. When used as an air-electrode, the NiFe2O4/FeNi2S4 HNSs can deliver a power density of 44.4 mW cm–2 and a superior cycling stability (only 0.6% decay after 900 cycles at 0.5 mA cm–2), making the resultant ZAB a highly efficient and robust one with a neutral aqueous electrolyte. Then this strategy was extended to other heterostuctured nanomaterials systems. The relevant materials synthesis, theoretical design and stuctural/device characterizations will be discussed.

Heterostructure-promoted oxygen electrocatalysis enables rechargeable zinc–air battery

2019 Fall National Meeting

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