Enhanced Oxygen Evolution Activity Aroused from Interfacial Electron Transfer and Synergism in Co(OH)2/MIL-88A Heterostructure

Abstract

The oxygen evolution reaction (OER) is a critical process in the operation of electrochemical water splitting. Metal-organic frameworks (MOFs) are applied in the field of OER electrocatalysis because of their unique structure, but the high impedance and unstable framework during pyrolysis remain unresolved. Here, MIL-88A (iron-based MOF) was modified by hydrolysis and loading Co(OH)2 to improve the catalytic activity. The electrochemical results showed that the Co(OH)2/MIL-88A achieved the optimized performance with the current density of 10 mA cm−2 at 278 mV (vs RHE). Density functional calculations (DFT) combined with characterization tests suggest that electrons transfer from Co(OH)2 to MIL-88A at the interface of the heterostructure, leading to a larger hole electron pair density. D-band theory calculations demonstrated that the synergistic effect of MIL-88A and Co(OH)2 in heterostructure strengthens the adsorption between active sites and adsorbate. The above proofs are the source of the excellent OER performance of the Co(OH)2/MIL-88A. The finding has certain reference significance for the heterogeneous treatment of iron-based MOF catalysts.