Molecular Regulation Based on Functional Trimetallic Metal-Organic Frameworks for Efficient Oxygen Evolution Reaction.

Abstract

Metal-organic frameworks (MOFs) as classic crystalline porous materials have attracted great interest in the catalytic field. However, how to realize molecular regulation of the MOF structure to achieve a remarkable oxygen evolution reaction (OER) electrocatalyst is still a challenge. Herein, we designed several series of special MOF materials to explore the relationship between the structure and properties as well as the related reactive mechanism. First, various metal centers, including Fe, Co, Ni, Zn, and Mg, were utilized to construct the first series of trimetallic MOF materials, namely, M3-MOF-BDC, where BDC = 1,4-benzenedicarboxylic acid, also known as terephthalic acid. Among of them, Fe3-MOF-BDC shows the best OER performance and only needs an overpotential of 312 mV at 10 mA cm-2. Then, functional BDC-X ligands (X = NH2, OH, NO2, DH) with various characteristic groups were selected to construct a new series, namely, Fe3-MOF-BDC-X, to further improve its OER electrocatalytic performance. As expected, Fe3-MOF-BDC-NH2 exhibited a greatly enhanced OER performance with ultralow Tafel slopes of 45 mV dec-1 and overpotentials of 280 mV at 10 mA cm-2 when the BDC-NH2 ligand was adopted, even superior to commercial IrO2 (323 mV) and most of the reported pristine MOFs as OER electrodes. Much higher structural stability was proven. The detailed structure-property relationship and mechanism are discussed. In a word, this work provides a very important theoretical basis for the design and exploration of new MOF electrocatalysts.