吉林大学冯守华团队报道了利用π-π型轨道耦合调控尖晶石八面体位的自旋态促进水氧化。相关研究成果于2024年6月24日发表于国际一流学术期刊《德国应用化学》。

自旋态通常被认为是释放能量相关催化剂反应性的关键开关，但精确操纵也很有挑战性，尤其是对于占据特定几何位置的活性中心离子。

该文采用3d（Co）-2p（O）-4f（Ce）的π-π型轨道耦合来调节Co₃O₄/CeO₂复合材料中八面体钴位（CoOh）的自旋态。更具体地说，通过调节CeO₂含量，CoOh的等效高自旋比可以达到54.7%，从而触发接近理论最佳值的平均eg填充（1.094）。相应的催化剂表现出优异的水氧化性能，在10 mA cm^-2下的过电位为251 mV，可与最先进的钴基氧化物相媲美。

计算的晶体轨道Hamilton布居和部分态密度分布中Ce t1u/t2u-O和CoOh t2g-Oπ型键之间的匹配能级证实了π-π型耦合，刺激了O2p和π对称Ce 4fyz2轨道之间的π-贡献，从而促进了电子从t2g跳到CoOh的eg轨道。

该项工作为理解复合氧化物中自旋态优化的4f和3d轨道耦合提供了深入的见解。

附：英文原文

Title: Manipulating the Spin State of Spinel Octahedral Sites via a π-π Type Orbital Coupling to Boost Water Oxidation

Author: Zhangtao Guo, Qian Zhu, Shaohua Wang, Mengpei Jiang, Xinxin Fan, Wanyu Zhang, Mei Han, Xiaotian Wu, Xiangyan Hou, Yaowen Zhang, Zhiyu Shao, Jingyu Shi, Xia Zhong, Shuting Li, Xiaofeng Wu, Keke Huang, Shouhua Feng

Issue&Volume: 2024-06-24

Abstract: Spin state is often regarded as the crucial valve to release the reactivity of energy-related catalysts, yet it is also challenging to precisely manipulate, especially for the active center ions occupied at the specific geometric sites. Herein, a π-π type orbital coupling of 3d (Co)-2p (O)-4f (Ce) was employed to regulate the spin state of octahedral cobalt sites (CoOh) in the composite of Co3O4/CeO2. More specifically, the equivalent high-spin ratio of CoOh can reach to 54.7% via tuning the CeO2 content, thereby triggering the average eg filling (1.094) close to the theoretical optimum value. The corresponding catalyst exhibits a superior water oxidation performance with an overpotential of 251 mV at 10 mA cm-2, rivaling most cobalt-based oxides state-of-the-art. The π-π type coupling corroborated by the matched energy levels between Ce t1u/t2u-O and CoOh t2g-O π type bond in the calculated crystal orbital Hamilton population and partial density of states profiles, stimulates a π-donation between O 2p and π-symmetric Ce 4fyz2 orbital, consequently facilitating the electrons hopping from t2g to eg orbital of CoOh. This work offers an in-depth insight into understanding the 4f and 3d orbital coupling for spin state optimization in composite oxides.

DOI: 10.1002/anie.202406711

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202406711