Optimizing Intermediate Adsorption on <scp> FeNi <sub>3</sub> </scp> Alloy by Substrate Defect‐Engineering for Enhanced Oxygen Electrocatalysis
Ruixi Jin, Congcong Yang, Zhihang Liu, Jingshuo Liu, Shilei Li, Yuanxin Liu, Keru Liu, Ran Yin, Jian Li, Likun Gao
Abstract
The rational development of high‐performance oxygen electrocatalysts, exhibiting synergistically optimized activity and durability, is essential for propelling the commercial viability of zinc‐air batteries (ZABs). In this study, alkali lignin is utilized as a coordinating ligand to synthesize defect‐rich nitrogen‐doped carbon loaded with FeNi 3 alloy (FeNi 3 @NAC) via a self‐assembly strategy accompanied by in situ pyrolysis. The abundant oxygen‐containing functional groups present in alkali lignin not only enhance metal anchoring but also increase the nitrogen doping levels. By controlling the pyrolysis temperature, the carbon edge defect and graphitic valley N within the catalyst can be effectively tuned. Density functional theory (DFT) calculations reveal that the presence of defect‐rich structures and graphitic valley N in the carbon matrix induce a downshift in the energy band structure of FeNi 3 , facilitating the desorption of oxygen intermediates and enhancing the kinetics of the ORR and OER. The FeNi 3 @NAC pyrolyzed at 800 °C (FeNi 3 @NAC‐800) with the highest proportions of carbon edge defects (37%) and graphitic valley N (0.76%), as well as sufficient mesopores, demonstrates outstanding bifunctional catalytic performance, achieving a high half‐wave potential of 0.86 V for the ORR and a low overpotential of 291 mV at 10 mA cm −2 for the OER. The ZAB incorporating FeNi 3 @NAC‐800 as the air cathode exhibits superior efficiency and durability, achieving a peak power density of 212.4 mW cm −2 , a specific capacity of 810.1 mAh g −1 , and long‐term stability exceeding 250 h at 5 mA cm −2 .