Tuning Bifunctional Properties of α-Fe2O3/Fe2TiO5/Pt Heterojunction Photoelectrode for Light-Induced Water Oxidation and Oxygen Reduction Activity

Abstract

Bifunctional photoelectrodes for water oxidation reaction (WOR) and oxygen reduction reaction (ORR) have paramount importance in solar-powered rechargeable metal-air batteries. Herein, we strategically fabricate a photoactive core-shell bifunctional electrocatalyst for cathode material in solar-powered rechargeable zinc-air battery (SRZB) with a type-II heterojunction band alignment, comprising n-type α-Fe2O3 nanorod core and a thin pseudobrookite phase of Fe2TiO5 shell. Pt nanoparticles (NPs) are precisely embedded on the Fe2TiO5 shell via atomic layer deposition technique to induce bifunctional WOR and ORR properties of the α-Fe2O3/Fe2TiO5 heterojunction photoelectrode. The WOR and ORR properties are optimized by precisely controlling Fe2TiO5 shell thickness and decorating Pt NPs on the Fe2TiO5 surface of the heterojunction photoelectrode. Finally, the α-Fe2O3/Fe2TiO5/Pt heterojunction photoelectrode is applied as cathode in SRZB and it exhibits excellent charging/discharging abilities with a voltage gap of only 0.3 V under 1 sun illumination, and maintains a good cycling stability of the SRZB over 50 h at 0.1 mA/cm2 in 1 M potassium hydroxide electrolyte. This research paves the way to fabricate bifunctional photoelectrode with efficient WOR and ORR properties for SRZB application.