Amorphous ferric oxide as a hole-extraction and transfer layer on nanoporous bismuth vanadate photoanode for water oxidation

An amorphous ferric oxide layer was prepared on a bismuth vanadate photoanode. This resulted in improved charge carrier separation and surface catalytic performance compared with the photoanode without the oxide layer. The photocurrent of the oxide-layer-containing photoanode was 2.52 mA/cm2 at 1.23 V versus the reversible hydrogen electrode, in potassium phosphate buffer (0.5 mol/L, pH = 7.0). The amorphous ferric oxide layer on the photoanode contained low-valence-state iron species (FeII), which enabled efficient hole extraction and transfer.