Liu Ming, Kong Lingjun, Wang Xuemin, He Jie, Bu Xian-He
School of Materials Science and Engineering, National Institute for Advanced Materials, TKL of Metal and Molecule Based Material Chemistry, Nankai University, Tianjin, 300350, P. R. China.
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) and College of Chemistry, Nankai University, Tianjin, 300071, P. R. China.
Small. 2019 Nov;15(45):e1903410. doi: 10.1002/smll.201903410. Epub 2019 Sep 13.
Benefiting from metal-organic frameworks (MOFs) unique structural characteristics, their versatility in composition and structure has been well explored in electrochemical oxygen evolution reaction (OER) processes. Here, a ligand/ionic exchange phenomenon of MOFs is reported in alkaline solution due to their poor stability, and the active species and reaction mechanism of MOFs are revealed in the OER process. A series of mixed Ni-MOFs and Fe-MOFs are synthesized by straightforward sonication and then directly used as catalyst candidates for OER in alkaline electrolyte. It can be confirmed via ex situ transmission electron microscopic images and X-ray diffraction patterns analysis, that the bimetallic hydroxide (NiFe-LDH) is generated in 1.0 m KOH in situ and acts as protagonist for oxygen evolution. The optimized catalyst (FN-2) exhibits a lower overpotential (275 mV at a current density of 10 mA cm ) and excellent long-term stability (strong current density for 100 h without fading). The revelation of the real active species of MOF materials may contribute to better understanding of the reaction mechanism.
受益于金属有机框架材料（MOFs）独特的结构特性，它们在组成和结构上的多功能性已在电化学析氧反应（OER）过程中得到充分探索。在此，由于MOFs稳定性较差，报道了其在碱性溶液中的配体/离子交换现象，并揭示了MOFs在OER过程中的活性物种和反应机理。通过直接超声合成了一系列混合Ni-MOFs和Fe-MOFs，然后直接用作碱性电解质中OER的候选催化剂。通过非原位透射电子显微镜图像和X射线衍射图谱分析可以证实，在1.0 m KOH中原位生成了双金属氢氧化物（NiFe-LDH），并作为析氧的主要物质。优化后的催化剂（FN-2）表现出较低的过电位（在电流密度为10 mA cm 时为275 mV）和出色的长期稳定性（强电流密度持续100 h不衰减）。MOF材料真实活性物种的揭示可能有助于更好地理解反应机理。
