Synergistic Strong-Weak Adsorption Coupling in the FeN <sub>6</sub> –CoN <sub>4</sub> Dual-Site Modulates Oxygen Reduction Pathways via Oxygen Adsorbate Evolution-to-Dissociation Transition
Min Jie Wang, Rumeng Ji, Chao Huang, Xiaodan Huang, Li Wang, Bingjie Zhou, S.C.H. Lu, Zehui Liu, Yongjun Han, Q. B. Li, Lishan Peng, qingfei liu, Jing Li, Liwei Mi, Yonghui Deng, Zidong Wei
Abstract
Atomically dispersed non-noble metal–nitrogen-carbon electrocatalysts could derive a four-electron oxygen reduction reaction (ORR) described via a typical adsorbate evolution mechanism (AEM), but their kinetics are limited by the linear scaling relationship (LSR) between the *OOH and *OH. Herein, we reported heteronuclear dual-site FeN 6 –CoN 4 materials obtained via integrating Fe 3+ and Co 2+ into pyrrole-functionalized g-C 3 N 4 nanosheets. Such electrocatalysts broke the conventional LSR through a shifted oxygen dissociation mechanism (ODM: *O 2 → *O + *OH → 2 *OH). Density functional theory calculations confirmed the strongest and weakest adsorption strengths of key ORR intermediates in the CoN 4 and FeN 6 sites with a conventional AEM pathway. Under the synergistic effect of dual-site strong-weak adsorption, FeN 6 –CoN 4 switched from ORR pathways to the ODM observed via in situ infrared spectroscopy for the rate-determining step (*O 2 → *O + *OH) with the decreased overpotentials of 0.41 V (FeN 6 ) and 0.50 V (CoN 4 ), enhancing intrinsic ORR kinetics. A Zn–air battery based on FeN 6 –CoN 4 demonstrated an open-circuit voltage of 1.65 V approaching the theoretical 1.68 V, high-power density of 314 mW cm –2, and durable discharge at 500 mA cm –2 . This work provides fundamental insights into dual-site synergy for regulating ORR pathways, offering a strategy for designing efficient atomic catalysts.