Enhanced Water Oxidation Photoactivity of Nano-Architectured alpha-Fe2O3-WO3 Composite Synthesized by Single-Step Hydrothermal Method

Abstract

This study reports the one-step in situ synthesis of a hematite-tungsten oxide (alpha-Fe2O3-WO3) composite on fluorine-doped tin oxide substrate via a simple hydrothermal method. Scanning electron microscopy images indicated that the addition of tungsten (W) precursor into the reaction mixture altered the surface morphology from nanorods to nanospindles. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of W content in the composite. From the ultraviolet-visible spectrum of alpha-Fe2O3-WO3, it was observed that absorption began at similar to 600 nm which corresponded to the bandgap energy of similar to 2.01 eV. The alpha-Fe2O3-WO3 electrode demonstrated superior performance, with water oxidation photocurrent density of 0.80 mA/cm(2) (at 1.6 V vs. reversible hydrogen electrode under standard illumination conditions; AM 1.5G, 100 mW/cm(2)) which is 2.4 times higher than alpha-Fe2O3 (0.34 mA/cm(2)). This enhanced water oxidation performance can be attributed to the better charge separation properties in addition to the large interfacial area of small-sized particles present in the alpha-Fe2O3-WO3 nanocomposite film.