Enhanced Photocatalytic Water Splitting by Plasmonic TiO₂–Fe₂O₃ Cocatalyst under Visible Light Irradiation

In this study, we introduce a plasmonic TiO₂–Fe₂O₃ cocatalyst photoelectrode to improve the water-splitting process. The absorption of incident photons and the separation rate of photogenerated electron–hole pairs are enhanced due to the broadband absorption and strong electric field of the composite formed from these two metal oxide semiconductors and plasmonic silver nanoparticles (Ag NPs). Plasmonic TiO₂–Fe₂O₃ cocatalyst photoelectrodes were fabricated using a precipitation and solution processing method. Under visible light irradiation, a photocurrent that is 20 times higher than that of pure Fe₂O₃ was observed using an optimized ratio of the plasmonic TiO₂–Fe₂O₃/Ag cocatalyst. The mechanism for this enhancement in the plasmonic cocatalyst system was investigated using different structural configurations of the photoelectrode. Both the crystallinity and absorption band edge of the TiO₂–Fe₂O₃ cocatalyst were characterized using X-ray diffraction (XRD) and ultraviolet–visible absorption spectroscopy (UV–vis). Furthermore, the spatial distribution of the photocurrent was investigated using this plasmonic cocatalyst system.