The presentation "Photo/electrochemistry of oxide semiconductors rationalized by band energetics" will be introduced by Prof. RNDr. Ladislav Kavan, DCs. from J. Heyrovský Institute of Physical Chemistry of the CAS, Department of Electrochemical Materials, Czech Republic.
The 34th NARECOM will take place on Wednesday, March 20, 2024, at 2:30. p.m.
Join Zoom Meeting: https://cesnet.zoom.us/j/92741141335
Abstract:
Optimizing the n-doped oxide semiconductors in photocatalysis and photoelectrochemistry requires information about the electronic structure near the conduction band minimum. Yet, its analysis is challenging, sometimes even impossible for fundamental reasons. Investigations of various materials (TiO2, SnO2, ZnO) from single crystals to polycrystalline and quasi-amorphous thin films provided self-consistent data, highlighting various general issues as well. Examples include: (i) Determination of flatband potentials and donor concentrations by Mott-Schottky plots, particularly for nanotextured materials. There is a significant spread of experimental values, and unrealistically large concentrations of majority charge carriers, which could even wrongly predict degenerated semiconductors; (ii) Calculation of work functions and band edges by DFT, ignoring the influence of sample environment and/or defects in real crystals; (iii) Measurement of work functions and band edges by a single experimental technique, e.g., by photoelectron spectroscopy (UPS, NAP-UPS), Kelvin probe (KP), or electrochemistry (EIS), disregarding the inherent non-reproducibility of values from individual techniques; (iv) Transposition of these problematic data, both theoretical and experimental, into photocatalysis, photovoltaics, and solar fuel generation; (v) Application of the Gärtner-Butler model for carrier dynamics, disregarding the gradient of electrochemical potentials as the principal driving force for the exciton dissociation.
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