Direct Z scheme- fashioned photoanode systems consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers toward enhanced photoelectrochemical water splitting performance

An elegant Z-scheme-fashioned photoanode consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers was rationally constructed. The photocurrent density of the Sb2Se3-Fe2O3 Z-scheme photoanode reached 3.07 mA cm(-2) at 1.23 V vs. RHE, three times higher than that of pristine Fe2O3 at 1.03 mA cm(-2). An obvious cathodic shift of the photocurrent onset potential of about 200 mV was also observed. The transient photovoltage response demonstrates that the suitable band edges (E-CB approximate to -0.4 eV and E-VB approximate to 0.8 eV) of Sb2Se3, match well with Fe2O3 (E-CB approximate to 0.29 eV and E-VB approximate to 2.65 eV), permitting the photoexcited electrons on the conduction band of the Fe2O3 to transfer to the valence band of Sb2Se3, and recombine with the holes therein, thus allowing a high concentration of holes to collect in the Fe2O3 for water oxidation. The transient absorption spectra further corroborate that the built-in electric field in the p-n heterojunction leads to a more effective separation and a longer lifetime of the charge carriers.