Hematite homojunctions without foreign element doping for efficient and stable overall water splitting

Abstract

A new strategy to prepare a hematite homojunction photoanode is proposed in this work. Hematite films with different Fermi levels are obtained by tuning the carrier concentrations in the films. This enables us to fabricate hematite homojunction photoelectrodes without foreign element doping by constructing bilayer films with different Fermi levels, and realize enhanced photoelectric conversion efficiency for highly efficient solar water splitting. The photocurrent density for the hematite homojunction is ∼1.1 mA cm⁻² at 1.23 V vs. RHE, which is almost 5 times that of single type hematite photoanodes. What is more, with this homojunction configuration, the hematite homojunctions show a 15 times higher stability compared with high-donor-concentration Fe₂O₃ photoelectrodes for oxygen evolution. Most importantly, overall water splitting is realized and the photocell still holds 92.2% of the efficiency for water oxidation even after 73 hours.