Axial Oxygen Ligands Regulating Electronic and Geometric Structure of Zn-N-C Sites to Boost Oxygen Reduction Reaction,Advanced Science

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Axial Oxygen Ligands Regulating Electronic and Geometric Structure of Zn-N-C Sites to Boost Oxygen Reduction Reaction
Advanced Science ( IF 14.3 ) Pub Date : 2023-06-26 , DOI: 10.1002/advs.202302152
Qiuyan Jin _{1,

2} , Chenhui Wang _{1,

2} , Yingying Guo _{1,

2} , Yuhang Xiao _{1,

2} , Xiaohong Tan _{1,

2} , Jianpo Chen _{1,

2} , Weidong He _{1,

2} , Yan Li _{1,

2} , Hao Cui _{1,

2} , Chengxin Wang _{1,

2}

Affiliation

Zn-N-C possesses the intrinsic inertia for Fenton-like reaction and can retain robust durability in harsh circumstance, but it is often neglected in oxygen reduction reaction (ORR) because of its poor catalytic activity. Zn is of fully filled 3d¹⁰4s² configuration and is prone to evaporation, making it difficult to regulate the electronic and geometric structure of Zn center. Here, guided by theoretical calculations, five-fold coordinated single-atom Zn sites with four in-plane N ligands is constructed and one axial O ligand (Zn-N₄-O) by ionic liquid-assisted molten salt template method. Additional axial O not only triggers a geometry transformation from the planar structure of Zn-N₄ to the non-planar structure of Zn-N₄-O, but also induces the electron transfer from Zn center to neighboring atoms and lower the d-band center of Zn atom, which weakens the adsorption strength of *OH and decreases the energy barrier of rate determining step of ORR. Consequently, the Zn-N₄-O sites exhibit improved ORR activity and excellent methanol tolerance with long-term durability. The Zn-air battery assembled by Zn-N₄-O presents a maximum power density of 182 mW cm⁻² and can operate continuously for over 160 h. This work provides new insights into the design of Zn-based single atom catalysts through axial coordination engineering.

中文翻译：

轴向氧配体调节 Zn-NC 位点的电子和几何结构以促进氧还原反应

Zn-NC具有类芬顿反应的固有惰性，可以在恶劣的环境下保持强大的耐久性，但由于其催化活性较差，在氧还原反应（ORR）中经常被忽视。 Zn为完全填充的3d ¹⁰ 4s ²构型，容易蒸发，因此难以调控Zn中心的电子和几何结构。在这里，在理论计算的指导下，通过离子液体辅助熔盐模板法构建了具有四个面内N配体和一个轴向O配体（Zn-N ₄ -O）的五重配位单原子Zn位点。额外的轴向O不仅引发了从Zn-N ₄平面结构到Zn-N ₄ -O非平面结构的几何转变，而且还诱导电子从Zn中心转移到邻近原子并降低了d带Zn原子中心，减弱了*OH的吸附强度，降低了ORR速率决定步骤的能垒。因此，Zn-N ₄ -O位点表现出改善的ORR活性和优异的甲醇耐受性以及长期耐久性。由Zn-N ₄ -O组装的锌空气电池的最大功率密度为182 mW cm ^-2 ，可以连续运行超过160小时。这项工作为通过轴向配位工程设计锌基单原子催化剂提供了新的见解。

更新日期：2023-06-26

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