CoNi Nanoparticle-Decorated ZIF-67-Derived Hollow Carbon Cubes as a Bifunctional Electrocatalyst for Zn–Air Batteries

CoNi nanoparticle-decorated hollow carbon cubes (CoNi-HCCs) were synthesized using ZIF-67 as a sacrificial template. The synthesis utilizes the thermal instability of ZIF-67, creating hollow carbon nanostructures while facilitating carbonization and introducing metal nanoparticles (e.g., CoNi). Prototype Zn–air batteries equipped with CoNi-HCCs exhibited a promising discharge potential of 1.21 V and a charge potential of 2.04 V at 20 mA cm–2. These values are superior to those of Pt–Ru, whose discharge and charge potentials were 1.20 and 2.08 V, respectively. CoNi-HCCs also displayed a high peak power density of 159.6 mW cm–2, which is significantly higher than the value for Pt–Ru (120.2 mW cm–2). After 90 h of bifunctional cycling at 10 mA cm–2, CoNi-HCCs only experienced an efficiency loss of 3.4% and maintained 55.3% battery efficiency, much more durable than Pt–Ru (41.7% after only 60 h).