Hydrogen production by water splitting using solar energy is one of the most promising ways to replace fossil fuel. In the past decades, metal oxide semiconductors have been extensively studied as a photoelectrode for solar water splitting. Among them, hematite (a-Fe2O3) has been identified as an excellent candidate as a photoelectrode since it is a chemically stable n-type semiconductor with the band gap energy of 2.2 eV. However, the photoelectrochemical performance of hematite is limited by several problems such as the poor minority charge carrier mobility, and the short hole diffusion length. To overcome these problems, tremendous efforts have been devoted to synthesize hematite nanomaterials. It is well-known that nanostructure possesses high surface-to-volume ratio, increased surface activity, and reduced diffusion length for minority charge carriers, so the hematite nanostructures are expected to excellent photoelectrochemical performance. For instance, photoanodes based on one-dimensional metal oxide nanostructures such as nanowire, nanorods, and nanotubes, have been widely exploited for water splitting applications. However, low-cost and high yield mass production of one-dimensional metal oxide materials as photoanodes remains still challenging. Herein, we report facile synthesis of one-dimensional hematite nanostructures for water splitting cells. The obtained efficiency is among the highest reported values for a hematite based photoelectrochemical cell. This enhancement in the photoconversion efficiency is related to the unique structural properties of the synthesized hematite nanotube films. The additional virtue, the simplicity in the synthesis method, would broaden the applications of the hematite nanotube films to various devices including sensors, batteries, and photochromic glasses.
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