Regulating the Spin-State of Rare-Earth Ce Single Atom Catalyst for Boosted Oxygen Reduction in Neutral Medium

The development of neutral zinc-air batteries (ZABs) is long been impeded by the sluggish oxygen reduction reaction (ORR) derived from insufficient O-2 activation and OH* blocking effect. Herein, the synthesis of a series of rare-earth Ce single-atom catalysts (CeNCs) is reported with enhanced spin-state for boosting neutral ORR. Experimental analysis and theoretical calculations indicate that the unique local coordination/geometric structure reshapes the electronic configuration of Ce sites to achieve a transition from 4d(10)4f(1) to 4d(8)4f(3). The high-spin Ce active sites accelerate the unpaired f electrons to occupy the anti-& pi; orbitals of O-2 and generate suitable binding strength with reaction intermediates. In neutral conditions, CeNC-40 exhibits excellent ORR performance with half-wave potentials of 0.78 V and negligible decay after 10 000 cycles. Additionally, the self-breathing ZABs based on CeNC-40 demonstrates a peak power density of 81 mW cm(-2) and impressive long-cycle stability (>1 600 cycles) at 2 mA cm(-2). This work presents an effective strategy for developing high-spin catalysts to address the challenges of neutral ZABs.