Photocatalytic water splitting presents a possible pathway for renewable hydrogen production. Iron Oxide (Fe₂O₃) in its hematite phase is a promising photocatalytic material due to its stability, non-toxicity, abundance and ability to absorb a large portion of the solar spectrum.
However, one of the major problems with using Fe₂O₃ as a photocatalyst is its low hole diffusion length. The diffusion length for Fe₂O₃ is 24 nm, approximately 42 times smaller than that of TiO₂. A film with wall thicknesses close to the diffusion length should allow better charge separation and utilisation at the film/electrolyte interface which results in higher charge migration properties. Therefore, the creation of a hematite Fe₂O₃ film with high porosity to reduced wall thickness was undertaken using an inverse opal technique developed at QUT.
The iron oxide inverse opals are prepared by templating iron nitrate with PMMA on a conductive glass slide and sintering to remove the PMMA and decompose the iron nitrate. This produced ordered nanoporous Fe₂O₃ films with approximate wall thicknesses of 50-100nm and pore diameters of 150-200nm (Figure). This paper will present the photocatalytic activity of these films for hydrogen production.