Mesoporous Fe₂O₃-TiO₂ Integrated with Plasmonic Ag Nanoparticles for Enhanced Solar H₂ Production

Present work describes a sol-gel assisted one-pot synthesis of mesoporous Fe₂O₃-TiO₂ nanocomposites (TiFe) with different Ti : Fe ratios, and fabrication of Ag-integrated with TiFe nanocomposites (TiFeAg) by a chemical reduction method and demonstrated for high solar H₂ generation activity in direct sunlight. Enhanced solar H₂ production is attributed to the light absorption from entire UV+Visible region of solar spectrum combined with Schottky (Ag-semiconductor) and heterojunctions (TiO₂-Fe₂O₃), as evidenced from HRTEM and various characterization studies. TiFeAg-2 thin film (1 wt % Ag-loaded TiFe-4) displayed the highest activity with a solar H₂ yield of 7.64 mmol h^-1g^-1, which is 48 times higher than that of bare TiO₂ and 5 times higher in thin film form compared to its powder counterpart. Schottky and heterojunctions formed at the interface efficiently separate the charge carriers and increase the hydrogen production activity. The highest H₂ production activity of TiFeAg-2 is partly attributed to the heterogeneous distribution of Fe³⁺ and metallic Ag-species with relatively high Ag/Ti surface atomic ratio. A plausible photocatalytic reaction mechanism on TiFeAg nanocomposite may involve the direct electron transfer from both Fe₂O₃ and TiO₂ to Ag nanoparticles which are subsequently utilized for the reduction of H⁺ to H₂.