Guo Zhangtao, Zhu Qian, Wang Shaohua, Jiang Mengpei, Fan Xinxin, Zhang Wanyu, Han Mei, Wu Xiaotian, Hou Xiangyan, Zhang Yaowen, Shao Zhiyu, Shi Jingyu, Zhong Xia, Li Shuting, Wu Xiaofeng, Huang Keke, Feng Shouhua
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Changchun, 130012, China.
Shenyang National Laboratory for Materials Science Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua RD, Shenyang, 110016, China.
Angew Chem Int Ed Engl. 2024 Sep 9;63(37):e202406711. doi: 10.1002/anie.202406711. Epub 2024 Aug 12.
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 (Co) in the composite of CoO/CeO. More specifically, the equivalent high-spin ratio of Co can reach to 54.7 % via tuning the CeO content, thereby triggering the average e 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, rivaling most cobalt-based oxides state-of-the-art. The π-π type coupling corroborated by the matched energy levels between Ce t/t-O and Co t-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 4f orbital, consequently facilitating the electrons hopping from t to e orbital of Co. This work offers an in-depth insight into understanding the 4f and 3d orbital coupling for spin state optimization in composite oxides.
自旋态通常被视为释放能量相关催化剂反应活性的关键阀门，但精确调控自旋态也具有挑战性，尤其是对于占据特定几何位点的活性中心离子而言。在此，通过3d（Co）-2p（O）-4f（Ce）的π-π型轨道耦合来调控CoO/CeO复合材料中八面体钴位点（Co）的自旋态。更具体地说，通过调节CeO含量，Co的等效高自旋比可达到54.7%，从而使平均电子填充量（1.094）接近理论最佳值。相应的催化剂表现出优异的水氧化性能，在10 mA cm时过电位为251 mV，与大多数最先进的钴基氧化物相当。在计算的晶体轨道哈密顿布居和部分态密度分布图中，Ce t/t-O与Co t-O π型键之间匹配的能级证实了π-π型耦合，激发了O 2p与π对称的Ce 4f轨道之间的π-电子给予，从而促进电子从Co的t轨道跃迁到e轨道。这项工作为理解复合氧化物中用于自旋态优化的4f和3d轨道耦合提供了深入见解。
