Dynamic Behavior of Single-Atom Catalysts in Electrocatalysis: Identification of Cu-N3 as an Active Site for the Oxygen Reduction Reaction

• DOI: 10.1021/jacs.1c03788
• Publication Date: 2021-08-31T16:39:49Z
• Authors: Ji Yang; Wengang Liu; Mingquan Xu; Xiaoyan Liu; Haifeng Qi; Leilei Zhang; Xiaofeng Yang; Shanshan Niu; Dan Zhou; Yuefeng Liu; Yang Su; Jian-Feng Li; Zhong-Qun Tian; Wu Zhou; Aiqin Wang; Tao Zhang
• Keywords: 01 natural sciences; 0104 chemical sciences

Atomically dispersed M-N-C (M refers to transition metals) materials represent the most promising catalyst alternatives precious metal Pt for electrochemical reduction of oxygen (ORR), yet genuine active sites in remain elusive. Here, we develop a two-step approach fabricate Cu-N-C single-atom catalysts with uniform and well-defined Cu2+-N4 structure that exhibits comparable activity superior durability comparison Pt/C. By combining operando X-ray absorption spectroscopy theoretical calculations, unambiguously identify dynamic evolution Cu-N4 Cu-N3 further HO-Cu-N2 under ORR working conditions, which concurrently occurs Cu2+ Cu+ is driven by applied potential. The increase Cu+/Cu2+ ratio reduced potential indicates low-coordinated Cu+-N3 real site, supported DFT calculations showing lower free energy each elemental step on than Cu2+-N4. These findings provide new understanding electrochemistry may guide design more efficient low-cost catalysts.