Construction of abundant Co3O4/Co(OH)2 heterointerfaces as air electrocatalyst for flexible all-solid-state zinc-air batteries

The heterostructure has its distinctive superiority for electrocatalysis ascribed to strain effect at heterointerfaces triggered by the lattice mismatch. Therefore, tailored electronic configurations of active centers, faster electronic conductivity associated with abundant active sites are induced as advantages to boost the relative electrocatalytic activity. Herein, we report the fabrication of Co3O4/Co(OH)2 hetero quantum dots as bifunctional electrocatalyst in rechargeable zinc air batteries (ZABs). To obtain catalytic current density of 10 mA cm−2 in oxygen evolution reaction (OER), Co3O4/Co(OH)2-HQDs only demands 300 mV overpotential, lower than Co(OH)2-QDs and Co3O4-QDs. The boosted OER performance is ascribed to the abundance of oxygen defects in Co3O4/Co(OH)2-HQDs resulting in more Co atoms in low coordination environment favorable for electro-adsorption of OH− species. In addition, a robust oxygen reduction reaction (ORR) catalytic activity is recorded for Co3O4/Co(OH)2-HQDs with half-wave potential of 844 mV vs. RHE. Because of the strong electronic interplay, appreciable stability is attained for Co3O4/Co(OH)2-HQDs. The manufactured aqueous rechargeable ZAB shows 1.4 times higher battery performance than Pt/C-IrO2 noble metal system. Furthermore, the all-solid-state ZAB also performs a considerable power density (57.4 mW cm−2) and its performance is well preserved during the flexibility test demonstrating the potential application in wearable devices.