A novel structure Ti/Fe2O3/Cu2S/Co(OH)x enhances the photoelectrochemical water splitting performance of iron oxide

Abstract

The slow oxygen evolution kinetics of iron oxide nanorod arrays have limited their applications in photocatalytic water splitting. Herein, we introduce p-type semiconductor cuprous oxide and further cover cobalt hydroxide ultrathin nanosheets on the surface of both by electrochemical deposition; these methods obviously enhanced the photoelectrochemical (PEC) water splitting performance of iron oxide nanorods on titanium sheet substrate. The photocurrent of this heterostructure reached 4.8 mA/cm2 at 1.23 V (vs. reversible hydrogen electrode) in a 1 M KOH aqueous solution under AM 1.5G illumination, which is much higher than the currently reported photocatalytic water splitting performance of iron oxide nanoarrays. The construction of Fe2O3/Cu2S p-n heterojunction accelerates the separation of photogenerated carriers in the main body of Fe2O3 nanorod arrays; as an excellent oxygen evolution catalyst (OEC), the introduction of Co(OH)x accelerates the kinetic process of interfacial water oxidation leading to the rapid depletion of photogenerated holes, which further improves the charge separation on the photoanode surface. Thus, the synergistic effect between Fe2O3/Cu2S p-n heterojunctions and oxygen evolution catalysts enhanced the iron oxide nanorod array photoanodes.