Quantum mechanics

Catalysis

Fermi level

Valence (chemistry)

Metallurgy

Materials science

Chromatography

Layer (electronics)

Nuclear magnetic resonance

Atomic physics

Biochemistry

Anatase

Rutile

Physics

Nanotechnology

Organic chemistry

Ionization

Crystallite

X-ray photoelectron spectroscopy

Work function

Condensed matter physics

Analytical Chemistry (journal)

Chemistry

Electron

Photocatalysis

Ionization energy

Surfaces

Polycrystalline anatase thin films, (001)- and (101)-oriented anatase TiO 2 single crystals and (001)- and (110)-oriented rutile TiO 2 single crystals with various surface treatments were studied by photoelectron spectroscopy to obtain their surface potentials. Regardless of orientations and polymorph, a huge variation of the Fermi level and work function was achieved by varying the surface condition. The most strongly oxidized surfaces are obtained after oxygen plasma treatment with a Fermi level ∼2.6 eV above the valence band maximum and ionization potentials of up to 9.5 eV (work function 7.9 eV). All other treated anatase surfaces exhibit an ionization potential independent of surface condition of 7.96 ± 0.15 eV. The Fermi level positions and the work functions vary by up to 1 eV. The ionization potential of rutile is ∼0.56 eV lower than that of anatase in good agreement with recent band alignment studies.

The Work Function of TiO2