Self-Optimized Metal–Organic Framework Electrocatalysts with Structural Stability and High Current Tolerance for Water Oxidation

Abstract

Metal–organic frameworks (MOFs) as electrocatalysts for oxygen evolution reaction (OER) typically suffer from fast degradation under harsh electrolyte conditions, impeding their practical use in industrial electrolyzers. Besides, the evolution of catalytic centers in MOFs and the related influence on their performance along the progress of reaction have rarely been studied. Here, we report a type of structurally stable bimetallic FeNi-MOF nanoarrays with self-optimized electrocatalytic activities in the oxygen production. Such a unique dynamic phenomenon is related with the gradual valence increments of Fe ions in MOFs, which trigger the continuous performance improvement before reaching an optimal steady state. Apart from the intact crystalline structures upon cycling, these FeNi-MOFs achieve low overpotentials of 239 and 308 mV at the current densities of 50 and 200 mA cm–2, respectively, and show durable operation for over 1033 h (>43 days) at 100 mA cm–2 and for another 200 h at 500 mA cm–2. A direct comparison of isostructural and single crystalline Fe-MOFs and Ni-MOFs resolves higher activities of Fe sites in the bimetallic MOFs, which are corroborated by theoretical calculations. The Fe–O bond covalency increment during Fe oxidation enhances the proton–electron transfers with the oxygen 2p-band closer to the Fermi level, thereby expediting the OER process. This work provides deep insights into the understanding of catalytic processes in heterometallic MOFs.

Facile Synthesis of Sulfate-Intercalated CoFe LDH Nanosheets Derived from Two-Dimensional ZIF-9(III) for Promoted Oxygen Evolution Reaction

“…Specifically, CoFe LDH nanosheets exhibit a higher TOF value, of 0.2716 s -1 at an overpotential of 300 mV, than that of ZIF-9(III) (0.0009 s -1 ). The molar number (n) is calculated based on the inductively coupled plasma-mass spectrometry (ICP-MS) results [13,46]. For CoFe LDH, the content of Co and Fe is 37.23 wt.…”

Construction and application of base-stable MOFs: a critical review

“…MOFs, being considered as a novel class of coordination complexes, have their unique advantages over traditional organometallic compounds. 201,202,211 The coordination environments and even the secondary microenvironments around the active sites can be precisely adjusted by rational structural design and post-synthetic modification. Moreover, the active centers can be arranged orderly and their relative positions can be finely tuned to facilitate the synergistic effect between them.…”

Multifunctional lanthanide MOF luminescent sensor built by structural designing and energy level regulation of a ligand

“…As a new type of organic and inorganic hybrid material, metalorganic frameworks (MOFs) integrate metal ions and organic ligands by coordinated interactions and have been studied in lots of fields, including gas storage and separation, [1][2][3][4][5] heterogeneous catalysis, [6][7][8][9][10] proton conduction, [11][12][13][14][15] luminescence detection, [16][17][18][19][20][21][22] etc. MOFs have a huge specific surface area and dense pore channels that can be designed and controlled.…”