Hybrid Co/CoO/Ce-Doped WO3 Nanoparticles on a ZIF-L Framework as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc–Air Batteries

The rational design of multiphasic interfaces is an efficient way to fabricate favorable catalysts for bifunctional oxygen reduction and oxygen evolution reactions (ORR/OER). Herein, the hybrid metallic nanoparticles composed of Co, CoO, and Ce-doped WO3 are anchored on the external surface of the preprepared catalysts (PZF-2-700) by pyrolyzing a unique polyoxometalate (POM)-containing metal–organic framework (MOF) precursor. The multiple heterointerfaces in the PZF-2-700 material surface provide defects as the catalytic active sites for the OER. Besides, the Co and CoO with Co–N–C, N–C, and Co–O in PZF-2-700 afford efficient catalytic performance for the ORR. Furthermore, the strong built-in field of PZF-2-700 enables the heterointerfaces with opposite charges and facilitates the electron transfer capacity throughout the structure. Based on this, the produced PZF-2-700 exhibits a small potential gap of 679 mV between the ORR and the OER. The homemade zinc–air battery (ZAB) with PZF-2-700 as the cathode catalyst displays a power density of 146.9 mW cm–2 and a charge/discharge cycling stability for 311 h with a charge–discharge period of 10 min, which offers a promising cathode catalyst for environment-friendly ZABs.