Anatase TiO<sub>2</sub> Surface Hydration: Infrared\nVibrational Assignment and Facet-Specific Stability

Anatase TiO<sub>2</sub> nanoparticles support a subtle\ndiversity\nof surface aqua and hydroxy coordination environments that are characteristic\nof distinct facets and defect sites. The disparate properties and\nstability of each molecularly or dissociatively absorbed water environment\nmay provide unique reactivity for facet- and site-selective atomic\nlayer deposition (ALD). We probe the temperature-dependent and facet-specific\nstretching frequency and stability of surface hydroxyls on faceted\nanatase TiO<sub>2</sub> nanoparticles via in situ diffuse reflectance\ninfrared Fourier transform spectroscopy (DRIFTS). Well-defined truncated\noctahedra, disks, and rods fabricated through hydrothermal synthesis\npresent dominant (101), (001),\nand (010) facets, respectively. The selective dehydration of discrete\nlocal coordination environments as a function of temperature provides\na potential pathway to site-selective and facet-selective ALD on metal\noxide nanomaterials.