Porous carbon cubes decorated with cobalt nanoparticles for oxygen evolution catalysis in Zn-air batteries

For commercialization of zinc-air batteries, it is important to replace expensive noble metal catalysts with inexpensive carbonaceous materials. Herein, an efficient oxygen evolution reaction (OER) catalyst composed of a unique porous tunnel carbon cube and cobalt nanoparticles (Co@NPCC) was fabricated to facilitate oxygen diffusion and create electron conduction networks. As an OER catalyst for zinc-air batteries (ZABs), the resulting Co@NPCC demonstrate enhanced OER activity, similar to that of the benchmark RuO₂. In OER performance, Co@NPCC exhibits the excellent mass activity of 49.9 mA mg⁻¹ at overpotential (η) of 0.47 V and the high current density of 91.5 mA cm⁻² at 1.75 V (vs RHE), compared to commercial RuO₂ catalysts. The use of Co@NPCC as the OER catalyst for ZAB maintains stable charge overpotential with as little as 0.05 V variation during 250 cycles, which extends the stable discharge-charge cycle performance compared to RuO₂. This work highlights a facile approach to fabricate OER catalysts without noble metals for enabling stable charge state and long life ZABs.