Jia Hongnan, Yao Na, Yu Can, Cong Hengjiang, Luo Wei
College of Chemistry and Molecular Sciences, Wuhan University Hubei, 430072, Wuhan, P. R. China.
State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University Hubei, 430073, Wuhan, P. R. China.
Angew Chem Int Ed Engl. 2023 Dec 4;62(49):e202313886. doi: 10.1002/anie.202313886. Epub 2023 Nov 3.
The electrolyte cations-dependent kinetics have been widely observed in many fields of electrocatalysis, however, the exact mechanism of the influence on catalytic performance is still a controversial topic of considerable discussion. Herein, combined with operando X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), we verify that the electrolyte cations could intercalate into the layer of pristine CoOOH catalyst during the oxygen evolution reaction (OER) process, while the bigger cations lead to enlarged interlayer spacing and increased OER activity, following the order Cs >K >Na >Li . X-ray absorption spectroscopy (XAS), in situ Raman, in situ Ultraviolet-visible (UV/Vis) spectroscopy, in situ XAS spectroscopy, cyclic voltammetry (CV), and theoretical calculations reveal that the intercalation of electrolyte cations efficiently modify the oxidation states of Co by enlarging the Co-O bonds, which in turn enhance the d-band center of Co, optimize the adsorption strength of oxygen intermediates, facilitate the formation of OER active Co(IV) species, and reduce the energy barrier of the rate-determing step (RDS), thereby enhancing the OER activity. This work not only provides an informative picture to understand the complicated dependence of OER kinetics on electrolyte cations, but also sheds light on understanding the mechanism of other electrolyte cation-targeted electrocatalysis.
电解质阳离子依赖的动力学已在许多电催化领域中被广泛观察到，然而，其对催化性能影响的确切机制仍是一个备受争议且讨论颇多的话题。在此，结合原位X射线衍射（XRD）和高分辨率透射电子显微镜（HRTEM），我们证实了在析氧反应（OER）过程中，电解质阳离子可插入原始CoOOH催化剂层中，而较大的阳离子会导致层间距增大和OER活性增加，顺序为Cs>K>Na>Li。X射线吸收光谱（XAS）、原位拉曼光谱、原位紫外可见（UV/Vis）光谱、原位XAS光谱、循环伏安法（CV）和理论计算表明，电解质阳离子的插入通过扩大Co-O键有效地改变了Co的氧化态，进而提高了Co的d带中心，优化了氧中间体的吸附强度，促进了OER活性Co(IV)物种的形成，并降低了速率决定步骤（RDS）的能垒，从而提高了OER活性。这项工作不仅为理解OER动力学对电解质阳离子的复杂依赖性提供了丰富的图景，也为理解其他以电解质阳离子为目标的电催化机制提供了启示。
