The evolution of bimetal hydroxide fragments from brucite to goethite in metal-organic frameworks for enhanced oxygen evolution reaction

Abstract

Due to the high surface areas and controllable structures, metal-organic frameworks (MOFs) have been regarded as a type of promising electrocatalyst for oxygen evolution reaction (OER). However, the unitary electronic structures and transfer channels always limit their catalytic activities during the OER process. Thus, the precise and favorable structural manipulation at the molecular level will be important to improve the electrocatalysis performance over MOF catalysts. Herein, the advantages of metal hydroxides are integrated into MOFs to design bimetallic hydroxide-mimicking MOFs. With one-dimensional (1D) Brucite [FeCo(OH)2] ribbon as the building block, bimetallic MOF (SNNU–FeCo–B) was produced. This type of inbuilt 1D ribbon was facilely evolved to 1D Goethite fragment (FeCoOOH) via changing the alkaline solutions and metal salts. And then SNNU-FeCo-G MOF that inserted the 1D Goethite ribbon was generated. Benefiting from the 1D ribbon-like hydroxide fragments in MOF’s frameworks, SNNU-FeCo-B and -G both exhibited much better OER catalytic reactivity compared to the original inorganic metal hydroxides. More importantly, we also demonstrate the 1D Goethite fragment is more favorable to enhance the electron transport capability, increase reactive areas and metal sites and thus exhibit higher electrocatalysis ability. Overall, this work opens a new structural design prospect to develop high-performance MOF electrocatalysts by regulating the MOF microstructure at the molecular level.