Oriented Ti doped hematite thin film as active photoanodes synthesized by facile APCVD

Abstract

To improve the optoelectronic properties of iron oxide as a photoelectrode, hematite (α-Fe₂O₃) thin films were doped with titanium using atmospheric pressure chemical vapor deposition (APCVD) for synthesis. The films were prepared by pyrolysis of Fe(CO)₅ and TiCl₄ precursors on fluorine-doped tin oxide (FTO) substrates and found to have a polycrystalline morphology with faceted particulates ∼20 to 50 nm in size with a preferred crystallographic growth along the [110] direction. The performance of the photoanodes was measured as a function of titanium concentration. A maximum efficiency was observed at ∼0.8 atom% Ti in hematite. The Incident Photon-to-current Conversion Efficiency (IPCE) to hydrogen was measured in alkaline electrolyte. Under an applied bias of 0.6 V vs.Ag/AgCl at 400 nm the IPCE for water splitting in alkaline solution was found to be 27.2%, the highest efficiency reported for Ti doped hematite photoanodes. The IPCEs of the photoanode thin films at lower applied bias were further increased by calcination at 500 °C and by use of glucose as an anolyte.