Selective Thermal and Photocatalytic Decomposition of Aqueous Hydrazine to Produce H₂ over Ag-Modified TiO₂...

An Ag-modified TiO₂ nanomaterial was prepared by a one-pot synthesis method using tetra butyl titanate, silver nitrate, and sodium hydroxide in water at 473 K for 3 h. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to determine the structure and morphology of the synthesized Ag-modified TiO₂ nanomaterial. The diffuse reflectance UV-visible and photoluminescence spectroscopy results revealed that metallic Ag nanoparticles decreased the optical band gap and photoluminescence intensity of the TiO₂. In addition, the Raman peak intensity and absorbance were increased after Ag modification onto TiO₂. The photocatalytic efficiency of the synthesized samples was tested for decomposition of aqueous hydrazine solution under visible light irradiation. The photocatalytic efficiency of Ag-modified TiO₂ nanomaterials was higher than that of bare TiO₂ and Ag metal NPs due to the synergistic effect between the Ag metal and TiO₂ structures. In addition, the surface plasmon resonance (SPR) electron transfer from Ag metal particles to the conduction band of TiO₂ is responsible for superior activity of TiO₂-Ag catalyst. The Ag-modified TiO₂ nanomaterials offered a 100% H₂ selectivity within 30 min of reaction time and an apparent rate constant of 0.018 min^-1 with an activation energy of 34.4 kJ/mol under visible light radiation.