Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Focus Session: Frontiers in Reducible Oxide Surface Science II

O 18.4: Vortrag

Montag, 12. März 2018, 16:15–16:30, HE 101

Electrochemical Characterization of Reducible Oxide Surfaces — •Ladislav Kavan — J. Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182 23 Prague, Czech Republic

The electronic band structure of semiconducting oxides (TiO2 or SnO2) is relevant to photo/electrochemistry and energy applications. The position of conduction band (CB) edge controls reductive photocatalytic reactions (e.g. hydrogen formation from water or CO2-reduction to solar fuels), Li-insertion electrochemistry, recombination blocking in perovskite solar cell and open-circuit potential of dye-sensitized solar cell. Recently, the reduction of CO2 to methane attracted attention for investigation of Mars atmosphere. The ALD-grown TiO2 and SnO2 layers are useful for electron selective contacts in perovskite solar cells. However, there is a considerable controversy about the position of CB in TiO2 (anatase, rutile, including the crystals with distinguished facets). The conflict is rationalized by considering the adsorption of OH- and H+ ions from the electrolyte solution on the electrode surface [5]. The facet specific electrochemistry of water splitting on TiO2 is addressing both the CB position and the electrocatalytic activity of the relevant crystal face. Doping of SnO2 by F- or Sb5+ provides the quasi-metallic (degenerate semiconductor) material, but little is known about similar doping-induced behavior of TiO2. We have recently found purely metal-like electrochemical properties of Ta-doped, optically transparent thin films of TiO2 (anatase) made by pulsed-laser deposition.