Zhang Chengxu, Qi Qianglong, Mei Yunjie, Hu Jue, Sun Minzi, Zhang Yingjie, Huang Bolong, Zhang Libo, Yang Shihe
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, 650093, China.
Adv Mater. 2023 Feb;35(8):e2208904. doi: 10.1002/adma.202208904. Epub 2022 Dec 27.
Reconstructing metal-organic framework (MOFs) toward a designed framework structure provides breakthrough opportunities to achieve unprecedented oxygen evolution reaction (OER) electrocatalytic performance, but has rarely, if ever, been proposed and investigated yet. Here, the first successful fabrication of a robust OER electrocatalyst by precision reconstruction of an MOF structure is reported, viz., from MOF-74-Fe to MIL-53(Fe)-2OH with different coordination environments at the active sites. Due to the radically reduced e -t crystal-field splitting in Fe-3d and the much suppressed electron-hopping barriers through the synergistic effects of the O species the efficient OER of in MIL-53(Fe)-2OH is guaranteed. Benefiting from this desired electronic structure, the designed MIL-53(Fe)-2OH catalyst exhibits high intrinsic OER activity, including a low overpotential of 215 mV at 10 mA cm , low Tafel slope of 45.4 mV dec and high turnover frequency (TOF) of 1.44 s at 300 mV overpotential, over 80 times that of the commercial IrO catalyst (0.0177 s ).Consistent with the density functional theory (DFT) calculations, the real-time kinetic simulation reveals that the conversion from O* to OOH* is the rate-determining step on the active sites of MIL-53(Fe)-2OH.
将金属有机框架（MOF）重构为设计的框架结构为实现前所未有的析氧反应（OER）电催化性能提供了突破性机遇，但这一设想即便曾经被提出过，也极少被研究。在此，报道了首次通过MOF结构的精确重构成功制备出一种稳健的OER电催化剂，即从MOF-74-Fe到在活性位点具有不同配位环境的MIL-53(Fe)-2OH。由于Fe-3d中e -t晶体场分裂的大幅降低以及通过O物种的协同效应极大地抑制了电子跳跃势垒，MIL-53(Fe)-2OH中高效的OER得以保证。受益于这种理想的电子结构，所设计的MIL-53(Fe)-2OH催化剂表现出高本征OER活性，包括在10 mA cm 时215 mV的低过电位、45.4 mV dec 的低塔菲尔斜率以及在300 mV过电位下1.44 s 的高周转频率（TOF），是商业IrO催化剂（0.0177 s ）的80多倍。与密度泛函理论（DFT）计算结果一致，实时动力学模拟表明从O到OOH的转化是MIL-53(Fe)-2OH活性位点上的速率决定步骤。
