LaTiOxNy Thin Film Model Systems for Photocatalytic Water Splitting: Physicochemical Evolution of the Solid-Liquid Interface and the Role of the Crystallographic Orientation

Pichler, Markus; Si, Wenping; Haydous, Fatima; Téllez, Helena; Druce, John; Fabbri, Emiliana; Kazzi, Mario El; Döbeli, Max; Ninova, Silviya; Aschauer, Ulrich Johannes; Wokaun, Alexander; Pergolesi, Daniele; Lippert, Thomas (2017). LaTiOxNy Thin Film Model Systems for Photocatalytic Water Splitting: Physicochemical Evolution of the Solid-Liquid Interface and the Role of the Crystallographic Orientation. Advanced functional materials, 27(20), p. 1605690. Wiley-VCH 10.1002/adfm.201605690

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The size of the band gap and the energy position of the band edges make several oxynitride semiconductors promising candidates for efficient hydrogen and oxygen production under solar light illumination. Intense research efforts dedicated to oxynitride materials have unveiled the majority of their most important properties. However, two crucial aspects have received much less attention: One is the critical issue of compositional/structural surface modifications that occur during operation and how these affect photoelectrochemical performance. The second concerns the relation between electrochemical response and the crystallographic surface orientation of the oxynitride semiconductor. These are indeed topics of fundamental importance, since it is exactly at the surface where the visible-light-driven electrochemical reaction takes place. In contrast to conventional powder samples, thin films represent the best model system for these investigations. This study reviews current state-of-the-art oxynitride thin film fabrication and characterization, before focusing on LaTiO2N, selected as a representative photocatalyst. An investigation of the initial physicochemical evolution of the surface is reported. Then, it is shown that after stabilization the absorbed photon-to-current conversion efficiency of epitaxial thin films can differ by about 50% for different crystallographic surface orientations, and be up to 5 times larger than for polycrystalline samples.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Ninova, Silviya and Aschauer, Ulrich Johannes

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

1616-301X

Publisher:

Wiley-VCH

Language:

English

Submitter:

Ulrich Johannes Aschauer

Date Deposited:

08 Jun 2017 12:19

Last Modified:

09 Jun 2017 06:54

Publisher DOI:

10.1002/adfm.201605690

BORIS DOI:

10.7892/boris.99013

URI:

https://boris.unibe.ch/id/eprint/99013

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