Single-atom Ce catalysts for rechargeable Zn–air batteries†

Rechargeable zinc–air batteries (ZABs) have attracted increasing attention in the field of energy storage and conversion owing to their high theoretical energy density, high efficiency and environmental compatibility. The development of bifunctional oxygen reduction/evolution (OER/OER) electrocatalysts is highly pivotal for ZABs. Accordingly, single-atom M–N–C catalysts are prospective candidates for oxygen electrocatalysis because they have the largest atomic utilization and possess highly adjustable electronic structures. Herein, a rare-earth bifunctional OER and ORR electrocatalyst, with atomic Ce sites embedded in N-doped graphene (Ce₁-NG), was designed and constructed. The atomically dispersed Ce sites were precisely analyzed using advanced characterization techniques. Ce₁-NG demonstrated an exceptional ORR performance with a half-wave potential (E_1/2) of 0.869 V and excellent OER activity with an overpotential (η₁₀) of 381 mV. The Ce₁-NG-based ZAB supplied an open-circuit voltage of 1.55 V and a peak power density of 152 mW cm⁻² with remarkable stability.