Newly designed ternary hematite-based heterojunction for PEC water splitting

Abstract

Hematite is recognized as a promising photoanode for photoelectrochemical water oxidation to produce solar hydrogen due to its favorable properties. However, the high charge carrier recombination rate due to low electrical conductivity and sluggish oxygen reduction kinetics of pure hematite hinder its photocatalytic activity. This work proposed a new hematite-based heterostructure of Ti-Fe2O3/Fe2TiO5/FeOOH, synthesized through a hydrothermal method. The photoanode morphology was branched nanorods that expanded their surface area and improved charge transfer at the photoanode/electrolyte interface. In a novel and complement modification approach, a thin pseudobrookite interlayer was applied between β-FeOOH electrocatalyst and Ti-doped hematite to suppress charge recombination, and enhance charge separation, leading to 32% and 26% increase in photocurrent density and solar to current efficiency, respectively. The photoanode exhibited a great improvement with the photocurrent density of 1.63 mA/cm2 at V = 1.5 V vs. RHE and the total electrical resistance of 2.3 kΩ.cm2 compared to the pure hematite.