Anodic self-organized transparent nanotubular/porous hematite films from Fe thin-films sputtered on FTO and photoelectrochemical water splitting

In the present work, we investigate the self-organized anodic formation of nanotubular/porous hematite structures from Fe thin films on fluorine doped tin oxide (FTO) substrates. We show, for different metal film thicknesses, that transparent layers of an aligned 1D oxide morphology can be grown by complete anodization of sputtered iron films. The nanoporous or nanotubular structures show very different potentials for use as a photoanode for solar water splitting. Best performance under AM 1.5 (100 mW cm(-2)) conditions were found for a nanoporous hematite structure obtained after anodizing a 570-nm-thick iron film and using combined air/Ar annealing to maintain the nanoscale morphology.