Oxygen Reduction Reaction Catalysts for Zinc-Air Batteries Featuring Single Cobalt Atoms in a Nitrogen-Doped 3D-Interconnected Porous Graphene Framework

Abstract

Single-atom catalysts (SACs) with high activity and efficient atom utilization for oxygen reduction reactions (ORRs) are imperative for rechargeable Zinc-air batteries (ZABs). However, it is still a prominent challenge to construct a noble-metal-free SAC with low cost but high efficiency. Herein, a novel nitrogen-doped graphene (NrGO) based SAC, immobilized with atomically dispersed single cobalt (Co) atoms (Co-NrGO-SAC), is reported for ORRs. In this 3D NrGO, the Co-N₄ sites endow high-efficiency ORR activity, and the 3D-interconnected porous architectures of NrGOs guarantee numberous active sites accessibility. Compared to commercial Pt/C catalyst (≈5.8 mA cm⁻²), as-prepared Co-NrGO-SACs presents considerable limiting current density of ≈5.9 mA cm⁻², prominent half-wave potential of ≈0.84 V, onset potential of ≈1.05 V, and as well as superior methanol resistance. Particularly, ZABs with Co-NrGO-SACs deliver remarkable power density (≈240 mW cm⁻²), super durability of over 233 h at 5 mA cm⁻², outperforming noble-metal-based benchmarks. This work provides an effective noble-metal free carbon-based SAC nano-engineering for superdurable ZABs.