Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 82: Structure of Solid/Liquid Interfaces I
O 82.1: Talk
Thursday, March 10, 2016, 10:30–10:45, H6
Probing the TiO2/Liquid Interface of a Photoelectrochemical Cell by X-Ray Photoelectron Spectroscopy — •Michael F. Lichterman1,2, Matthias H. Richter1,2,7, Shu Hu1,2, Ethan J. Crumlin3, Stephanus Axnanda3, Marco Favaro3,4, Walter Drisdell3,4, Zahid Hussain3, Bruce S. Brunschwig1, Zhi Liu3,5,6, Nathan S. Lewis1,2, and Hans-Joachim Lewerenz1,2 — 1Caltech, Pasadena, USA. — 2JCAP, Pasadena, USA. — 3LBNL, Berkeley, USA. — 4JCAP, Berkeley, USA. — 5Chinese Academy of Sciences, China. — 6ShanghaiTech University, China. — 7BTU C-S, Cottbus, Germany.
Amorphous TiO2 coatings can stabilize semiconductor photoanodes such as Si, GaAs, and GaP that are otherwise unstable in aqueous media [1]. Using tender X-rays with their substantially increased inelastic mean free scattering length of photoelectrons and using the classical three-electrode potentiostatic arrangement allows one to follow of the influence of the applied potentials on the semiconductor electrode energetics such as band bending and band edge shifts directly [2, 3]. The observed shifts in binding energy with respect to the applied potential have directly revealed rectifying junction behavior on semiconducting samples. Accumulation, depletion and Fermi level pinning were observed. Additionally, the non-linear response of the core level binding energies to changes in the applied electrode potential has revealed the influence of defect-derived electronic states on the Galvani potential across the complete cell. [1] Science 344 (2014) 1005; [2] Sci Rep 5 (2015) 9788; [3] Ener & Env Sci 8 (2015) 2409