Enhanced Photoelectrochemical Water Oxidation by Fabrication of p-LaFeO3/n-Fe2O3 Heterojunction on Hematite Nanorods

Abstract

The LaFeO3 film exhibits interesting p-type behavior and stable photocatalytic hydrogen production in aqueous solution, and we combine it with α-Fe2O3 nanorods to form a p-LaFeO3/n-Fe2O3 heterojunction to improve the photoeletrochemical (PEC) water oxidation performance of hematite. An atomic layer deposition (ALD) technique is adopted to deposit La2O3 controllably on β-FeOOH nanorods, and the p-LaFeO3/n-Fe2O3 heterojunction is achieved by post-thermal treatment, which is evidenced by the XRD, XPS, and HRTEM images. Due to the well-matched band levels of LaFeO3 and α-Fe2O3, the onset potential for photocurrent is negatively shifted by ∼50 mV. Meanwhile, the photocurrent density is promoted from 0.37 to 0.58 mA/cm2 at 1.23 V versus RHE owing to the accelerated charge separation within the space depletion layer induced by the build-in potential. Furthermore, the heterojunction is further modified by CoOx cocatalyst to improve the surface water oxidation kinetics, and the photocurrent density is promoted to ...