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

This study reports the one-step in situ synthesis of a hematite–tungsten oxide (α-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 α-Fe2O3–WO3, it was observed that absorption began at ∼ 600 nm which corresponded to the bandgap energy of ∼ 2.01 eV. The α-Fe2O3–WO3 electrode demonstrated superior performance, with water oxidation photocurrent density of 0.80 mA/cm2 (at 1.6 V vs. reversible hydrogen electrode under standard illumination conditions; AM 1.5G, 100 mW/cm2) which is 2.4 times higher than α-Fe2O3 (0.34 mA/cm2). 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 α-Fe2O3–WO3 nanocomposite film.