Ladislav Kavan

Jeudi 12 juin à 13h30 - Photoelectrochemistry of TiO₂, SnO₂, ZnO: Fundamentals, Pitfalls, Applications

Ladislav KAVAN

J. Heyrovsky Institute of Physical Chemistry, Prague, CZ

Abstract :

Materials based on TiO₂, SnO₂ and ZnO triggered the rise of semiconductor photoelecrochemistry in the last century, with pivotal advances in photocatalysis, photovoltaics, and solar fuel generation from, e.g., H₂O. N₂, CO₂. These three materials are currently producing ca. 130 scientific publications daily! This deluge of information causes, however, conflicting interpretations, oversimplifications, and misconceptions, too [1]. Examples are: (i) Determination of flatband potentials and donor concentrations by Mott-Schottky analysis, e.g., for nanotextured materials; (ii) Calculation of work functions and band edges by DFT ignoring the effects of crystal environment and/or imperfections; (iii) Measurement of work functions and band edges by photoelectron spectroscopy (XPS/UPS/NAP) and Kelvin probe; (iv) Application of the classical Gärtner-Butler model for carrier dynamics in semiconductor photoanodes, discounting the gradient of electrochemical potentials for the e^-/h⁺ separation; (v) The “superhydrophilicity” in UV-irradiated titania is caused by selective adsorption/photodegradation of airborne carboxylic acids, rather than by structural modifications of the TiO₂ surface.

[1] L. Kavan, Electrochemistry and band structure of semiconductors (TiO₂, SnO₂, ZnO): Avoiding pitfalls and textbook errors, J. Solid State Electrochem. 28 (2024) 829-845.

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