Cheng Fanpeng, Li Zhongjian, Wang Lin, Yang Bin, Lu Jianguo, Lei Lecheng, Ma Tianyi, Hou Yang
Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
Mater Horiz. 2021 Feb 1;8(2):556-564. doi: 10.1039/d0mh01757d. Epub 2020 Dec 24.
Metal-organic frameworks (MOFs) have been identified as one of the promising electrocatalysts for the oxygen evolution reaction (OER). However, direct observation of the electrocatalytic behavior of MOF-based electrocatalysts remains extremely challenging, which is of great significance to understand their electrocatalytic mechanism. Herein, we developed a vertically oriented Ni-based MOF nanosheet array doped with 2.09 wt% Ce (denoted as Ce-NiBDC/OG). Ce-NiBDC/OG displayed a low overpotential of 265 mV to deliver a 10 mA cm current density for the OER. In situ spectroscopy and operando microscopy visualized the phase transformation behavior of Ce-NiBDC/OG to Ce-doped NiOOH induced by electrochemical activation, which was regarded as the real active site. Mechanistic studies revealed that, for the Ce-NiBDC/OG-derived catalyst, the doping of Ce species in NiOOH significantly increased the adsorption of *OH, and further reduced the energy barriers of the rate-determining step (*OH→*O).
金属有机框架材料（MOFs）已被确定为析氧反应（OER）中一种有前景的电催化剂。然而，直接观察基于MOF的电催化剂的电催化行为仍然极具挑战性，这对于理解其电催化机理具有重要意义。在此，我们开发了一种垂直取向的掺杂2.09 wt% Ce的镍基金属有机框架纳米片阵列（记为Ce-NiBDC/OG）。对于OER，Ce-NiBDC/OG在10 mA cm电流密度下表现出265 mV的低过电位。原位光谱和原位显微镜观察到电化学活化诱导Ce-NiBDC/OG向Ce掺杂的NiOOH的相变行为，这被视为真正的活性位点。机理研究表明，对于Ce-NiBDC/OG衍生的催化剂，Ce物种在NiOOH中的掺杂显著增加了*OH的吸附，并进一步降低了速率决定步骤（*OH→*O）的能垒。
