α-Fe2O3 nanoarrays photoanodes decorated with Ni-MOFs for enhancing photoelectrochemical water oxidation

Owing to severe recombination of photogenerated charges, sluggish kinetics of oxygen evolution reaction (OER) and high overpotential, the efficiency of photoelectrocatalytic (PEC) water splitting is severely restricted currently. Herein, a metal-organic framework (Ni-MOF) as cocatalyst has been introduced onto Fe2O3 nanoarrays for PEC water oxidation. The new Ni-MOFs/Fe2O3 photoanode obviously improves the PEC water oxidation performance with respect to the Fe2O3. Specifically, a high photocurrent density is achieved on the Ni-MOF/Fe2O3 film, which corresponds to two-fold over the pristine Fe2O3 film at 1.23 V vs. RHE. Moreover, the photoanode also exhibits a significant cathodic shift of the onset potential (similar to 240 mV) relative to the bare Fe2O3. The enhanced PEC performance is attributed to effective utilization the surface-reaching holes and reduction of the surface charge recombination, which are confirmed by electrochemical impedance spectroscopy and the derived Bode analysis. This study brings new insight into the development of MOF-based materials in the field of PEC water splitting. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.