Bimetallic Oxyhydroxide Cocatalyst Derived from CoFe MOF for Stable Solar Water Splitting

Metal-organic frameworks (MOFs) as efficient electrocatalysts can be employed as the promising cocatalysts in photoelectrochemistry.Herein, a strategy is developed to metal-organic frameworks as oxygen evolution cocatalyst (OEC) combined with semiconductor for improving the charge transport and reducing the bulk/surface carrier recombination.This advanced CoFe MOF/BiVO4 photoanode exhibits a photocurrent density of 4.5 mA•cm -2 at 1.23 V (vs.RHE) under AM 1.5G illumination, achieving outstanding long-term photostability.Remarkably, with the reconstruction of MOF in the longterm water oxidation reaction, more stable metal oxyhydroxides are formed on the surface of BiVO4 and the photocurrent density of the photoelectrode is further enhanced to 5 mA•cm -2 .From density functional theory calculations, the enhanced photoelectrochemical (PEC) performance can be attributed to the coupling effect between Co and Fe decreasing the free energy barriers and accelerating the reaction kinetics.This work focuses on the reconfiguration of CoFe MOF catalyst to bimetallic hydroxide during long-term water oxidation.This work enables us to develop an effective pathway to design and fabricate efficient and stable photoanodes through MOFs catalysts for feasible PEC water splitting.