In situ grown three-dimensional porous Co₃O₄/graphdiyne oxide hybrid nanomaterials with sea urchin-like structures for high-performance zinc–air batteries

Abstract As a promising energy conversion system, zinc air battery (ZAB) usually suffers from short cycle life and poor reversibility due to the slow kinetics of the redox reaction on the air cathode, making it a big-barriers in practical applications. Herein, three-dimensional (3D) porous Co₃O₄/graphdiyne oxide (GDYO) hybrid nanomaterials with sea urchin-like structures have been prepared by in-situ epitaxial growth. The 3D porous Co₃O₄/GDYO hybrid nanomaterials with sea urchin-like structures expand the larger contact area between the electrolyte and the electrode, which provide abundant channels for ion diffusion and electron transport with enhanced charge transfer kinetics and structural stability. The 3D porous Co₃O₄/GDYO hybrid nanomaterials with sea urchin-like structures shows excellent bifunctional electrocatalytic activity for both oxygen evolution reaction (OER) (onset potential of 1.38 V, overpotential of 335 mV at 10 mA cm⁻²) and oxygen reduction reaction (ORR) (onset potential of 0.84 V, half-wave potential of 0.6 V). ZABs fabricated with 3D porous Co₃O₄/GDYO hybrid nanomaterials as cathode display a high power density of 96 m W cm⁻², an open circuit voltage of 1.53 V, as well as a specific capacity of 799.5 mA h g⁻¹ (at 10 mA cm⁻²) and a corresponding energy density of 965 Wh kg⁻¹. Further, its charge and discharge voltages remain stable for over 400 h at a constant current charge–discharge cycling of 3 mA cm⁻². This work offers novel insights on developing excellent bifunctional electrocatalysts for both OER and ORR, which expands a new application of GDYO on ZABs.