通过Ce(4f)─O(2p)─Co(3d)梯度轨道耦合增强Co?O共价以实现高效析氧,Advanced Materials

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通过Ce(4f)─O(2p)─Co(3d)梯度轨道耦合增强Co?O共价以实现高效析氧
Advanced Materials ( IF 27.4 ) Pub Date : 2023-04-18 , DOI: 10.1002/adma.202302462
Meng Li _{1,

2} , Xuan Wang ₁ , Kun Liu ₁ , Huamei Sun ₁ , Dongmei Sun ₁ , Kai Huang ₂ , Yawen Tang ₁ , Wei Xing _{3,

4} , Hao Li ₅ , Gengtao Fu ₁

Affiliation

稀土（RE）基过渡金属氧化物（TMO）正在成为析氧反应（OER）的前沿领域，但有关其电催化机制和活性位点的知识非常有限。在这项工作中，通过有效的等离子体（P）辅助策略成功设计并合成了CoO上原子分散的Ce作为模型（P-Ce SAs@CoO），以研究RE-TMO系统中OER性能的起源。P-Ce SAs@CoO表现出良好的性能，在10 mA cm ^-2下的过电势仅为261 mV ，并且具有强大的电化学稳定性，优于单独的CoO。X射线吸收光谱和原位电化学拉曼光谱表明，Ce诱导的电子重新分布抑制了Co - O - Ce单元位点中的Co - O键断裂。理论分析表明，梯度轨道耦合增强了Ce(4f)─O(2p)─Co(3d)单元活性位点的Co  O共价性，并优化了Co-3d-e g 占据，_可以平衡吸附强度中间体的数量，进而达到理论 OER 最大值的顶点，与实验观察结果非常一致。人们相信，这种Ce-CoO模型的建立可以为高性能RE-TMO催化剂的机理理解和结构设计奠定基础。

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Reinforcing Co?O Covalency via Ce(4f)─O(2p)─Co(3d) Gradient Orbital Coupling for High-Efficiency Oxygen Evolution

Rare-earth (RE)-based transition metal oxides (TMO) are emerging as a frontier toward the oxygen evolution reaction (OER), yet the knowledge regarding their electrocatalytic mechanism and active sites is very limited. In this work, atomically dispersed Ce on CoO is successfully designed and synthesized by an effective plasma (P)-assisted strategy as a model (P-Ce SAs@CoO) to investigate the origin of OER performance in RE–TMO systems. The P-Ce SAs@CoO exhibits favorable performance with an overpotential of only 261 mV at 10 mA cm⁻² and robust electrochemical stability, superior to individual CoO. X-ray absorption spectroscopy and in situ electrochemical Raman spectroscopy reveal that the Ce-induced electron redistribution inhibits CoO bond breakage in the CoOCe unit site. Theoretical analysis demonstrates that the gradient orbital coupling reinforces the CoO covalency of the Ce(4f)─O(2p)─Co(3d) unit active site with an optimized Co-3d-e_g occupancy, which can balance the adsorption strength of intermediates and in turn reach the apex of the theoretical OER maximum, in excellent agreement with experimental observations. It is believed that the establishment of this Ce–CoO model can set a basis for the mechanistic understanding and structural design of high-performance RE–TMO catalysts.

更新日期：2023-04-18

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