Morphology-controlled α-Fe2O3 nanostructures on FTO substrates for photoelectrochemical water oxidation

Abstract

Hematite (α-Fe2O3) nanostructured films were prepared on fluorine doped tin oxide substrates by heat treating the hydrothermally prepared precursor films. By using different additives in the hydrothermal preparations, the final hematite nanostructures could be controlled to be square prisms, nanorods and polyhedral blocks, of which the square prisms and the nanorods were vertically grown on the substrates and possessed preferred orientation along [110] direction while the polyhedral blocks were composed of small isotropic nanoparticles. When used as photoanodes, the α-Fe2O3 nanorod films showed better photoelectrochemical water oxidation performance than the other two kinds of α-Fe2O3 films. Analyses based on XRD, SEM and electrochemical impedance spectroscopy revealed that the α-Fe2O3 nanorods had characteristics including small diameter, abundant through-holes, growing along [110] axis vertical to the substrate and high donor density, which are believed to contribute to the good photoelectrochemical water oxidation performance. On the ground that α-Fe2O3 is very promising semiconductor material for photoelectrochemical water oxidation application, such morphology controlled, nanostructured hematite α-Fe2O3 films based on simple preparation method are envisioned to provide valuable platforms for supporting catalysts and co-catalysts to achieve efficient light-assisted oxidation of water.