Atomically Dispersed Co<sub>2</sub> -N<sub>6</sub> and Fe-N<sub>4</sub> Costructures Boost Oxygen Reduction Reaction in Both Alkaline and Acidic Media.

Wang, Zhe; Jin, Xiaoyan; Zhu, Chao; Liu, Yipu; Tan, Hua; Ku, Ruiqi; Zhang, Yongqi; Zhou, Liujiang et al. · Adv Mater · 2021

basic_science · Level V

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Abstract

Polynary transition-metal atom catalysts are promising to supersede platinum (Pt)-based catalysts for oxygen reduction reaction (ORR). Regulating the local configuration of atomic catalysts is the key to catalyst performance enhancement. Different from the previously reported single-atom or dual-atom configurations, a new type of ternary-atom catalyst, which consists of atomically dispersed, nitrogen-coordinated Co-Co dimers, and Fe single sites (i.e., Co<sub>2</sub> -N<sub>6</sub> and Fe-N<sub>4</sub> structures) that are coanchored on highly graphitized carbon supports is developed. This unique atomic ORR catalyst outperforms the catalysts with only Co<sub>2</sub> -N<sub>6</sub> or Fe-N<sub>4</sub> sites in both alkaline and acid conditions. Density functional theory calculations clearly unravels the synergistic effect of the Co<sub>2</sub> -N<sub>6</sub> and Fe-N<sub>4</sub> sites, which can induce higher filling degree of Fe-d orbitals and favors the binding capability to *OH intermediates (the rate determining step). This ternary-atom catalyst may be a promising alternative to Pt to drive the cathodic ORR in zinc-air batteries.