Determining the Catalytic Activity of Transition Metal-Doped TiO₂ Nanoparticles Using Surface Spectroscopic Analysis

The modified TiO₂ nanoparticles (NPs) to enhance their catalytic activities by doping them with the five transition metals (Cr, Mn, Fe, Co, and Ni) have been investigated using various surface analysis techniques such as scanning electron microscopy (SEM), Raman spectroscopy, scanning transmission X-ray microscopy (STXM), and high-resolution photoemission spectroscopy (HRPES). To compare catalytic activities of these transition metal-doped TiO₂ nanoparticles (TM-TiO₂) with those of TiO₂ NPs, we monitored their performances in the catalytic oxidation of 2-aminothiophenol (2-ATP) by using HRPES and on the oxidation of 2-ATP in aqueous solution by taking electrochemistry (EC) measurements. As a result, we clearly investigate that the increased defect structures induced by the doped transition metal are closely correlated with the enhancement of catalytic activities of TiO₂ NPs and confirm that Fe- and Co-doped TiO₂ NPs can act as efficient catalysts.