Niobium-doped Hematite Photoanodes Prepared through Low-Cost Facile Methods for Photoelectrochemical Water Splitting

Producing solar fuels through semiconductor-based photocatalytic water splitting is one of the main options for worldwide employment of non-fossil energy sources. Nonetheless, the relatively low efficiency of the known photocatalysts, the high prices of composing elements, and the costly preparation methods render expensive devices that would not be economically competitive with fossil energy sources. Herein, we present a facile method for the preparation of both round hematite (Fe2O3) nanoparticles, with average diameter of (56 +/- 7) nm, and of niobium-doped hematite nanoparticles with similar size and morphology. Thin films of these nanoparticles were assembled through electrophoretic deposition, resulting in homogeneous photoanodes with nanometer thickness that can split water, under simulated solar irradiation, to produce oxygen in a photoelectrochemical cell. The optimization of the film composition and thickness resulted in the improvement of the photocurrent from 352.3 to 1,342.5 mu A cm(-2) at 1.23 V vs RHE for the pristine hematite and Nb-doped hematite, respectively, both with thickness of (499 +/- 63) nm. This enhancement in the oxidation reaction yield is a clear consequence of the improvement of charge carriers transport along the nanoparticle structure due to niobium doping and adequate light absorption/charge transfer balance of the photoelectrode under operation.

Automated summary

Producing solar fuels through semiconductor-based photocatalytic water splitting is a promising solution for global adoption of renewable energy sources. This study introduces a simple method for preparing nanostructured hematite and niobium-doped hematite nanoparticles, which can be assembled into thin films for use as photoanodes in photoelectrochemical cells. The optimization of film composition and thickness significantly improves the photocurrent and enhances the efficiency of water splitting, making these materials more economically competitive.