Improved charge separation efficiency of hematite photoanodes by coating an ultrathin p-type LaFeO overlayer.

Many metal-oxide candidates for photoelectrochemical water splitting exhibit localized small polaron carrier conduction. Especially hematite (α-FeO) photoanodes often suffer from low carrier mobility, which causes the serious bulk electron-hole recombination and greatly limits their PEC performances. In this study, the charge separation efficiency of hematite was enhanced greatly by coating an ultrathin p-type LaFeO overlayer. Compared to the hematite photoanodes, the solar water splitting photocurrent of the FeO/LaFeO n-p junction exhibits a 90% increase at 1.23 V versus the reversible hydrogen electrode, due to enlarging the band bending and expanding the depletion layer.