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The Thin Films and Interfaces Group

Thin films are nowadays utilized in many applications, ranging from semiconductor devices to optical coatings and are even present in pharmaceuticals (polymers). This wide-spread application of films with thicknesses from atomic monolayers to microns is due to the developments of thin film deposition techniques. Thin films are also important for studies of materials with new and unique properties due to the possibility of tuning their crystallographic and morphological properties. The thin film approach, i.e. the presence of interfaces (to a substrate or the film surface) adds more degrees of freedom for influencing the properties of materials, e.g. by lattice strain or surface functionalization. For these fundamental studies of material properties large research facilities such as synchrotron radiation or neutron spallation sources are one of the keys that the Paul Scherrer Institute (PSI) provides.

Our group focuses on the preparation of highly defined thin films by pulsed laser deposition (PLD) for applications in energy technology, but also for new properties, such as multiferroicity. We are working on the fundamental understanding of the PLD process, the influence of strain on material properties and we utilize the large facilities at PSI (neutrons, muons, and photons from the SLS). We therefore cooperate with many groups within the NUM, ENE and SYN divisions, and offer in addition a thin film deposition service. Top

Upcoming Conference

2017 MRS Spring Meeting & Exhibit

April 17-21, 2017
Phoenix, Arizona, USA
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May 2017

2017 E-MRS Spring Meeting and Exhibit

May 22-26, 2017
Strasbourg, France
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Upcoming Group Seminars

Speaker: Prof. Christian Rüegg
Head of the Neutron and Muon Research Division, PSI

Date: Monday 23 January 2017 16:30
Room: OFLG/402

Multi-scale design guidelines for photo-electrochemical fuel processing reactors - Abstract
Speaker: Prof. Sophia Haussener
Laboratory of Renewable Energy Science and Engineering, EPFL

Date: Monday 06 February 2017 16:30
Room: OFLG/402

Universality of the XY system with dipolar interaction on the square lattice
Speaker: LMX Meeting: Dominik Schildknecht
Date: Tuesday 07 February 2017 9:30
Room: ODRA/111

Speaker: A. Palla-Papavlu
Date: Monday 20 February 2017 16:30
Room: OFLG/402


Most recent Paper

Wenping Si, Daniele Pergolesi, Fatima Haydous, Aline Fluri, Alexander Wokaun, and Thomas Lippert
Investigating the behavior of various cocatalysts on LaTaON2 photoanode for visible light water splitting
Phys.Chem.Chem.Phys. 19, 656 (2017)

We performed a comparative study on the photoelectrochemical performance of LaTaON2 loaded with NiOx, Ni0.7Fe0.3Ox, CoOx and IrOx as cocatalysts. Ni-based oxides lead to the highest improvement on the photoelectrochemical performance, while CoOx and IrOx also enhance the performance though to a lower extent, but they simultaneously introduce more pseudocapacitive current thus resulting in an inefficient utilization of the photo-generated holes. Repetitive voltage cycling between 1.0 VRHE and 1.6 VRHE transforms the NiOx and Ni0.7Fe0.3Ox into oxyhydroxides known to possess higher catalytic activities. However, these oxyhydroxides lead to lower photoelectrochemical performance compared to the as-loaded oxides, most robably due to the decay of the passivation centers at the photoelectrode–cocatalyst interface. High catalytic activities cannot be achieved without sufficient passivation of surface recombination states. Despite that the photoelectrochemical performance of LaTaON2 can be improved by cocatalysts, the maximum achievable photocurrent density is still not comparable to that reported for other oxynitride compounds. Our study suggests that poor electronic conductivity or severe bulk recombination of the photo-generated electron–hole pairs are the main limiting factors for the photonto-current conversion efficiency in LaTaON2 photoanodes.
Keywords: oxynitrides; photocatalysis; visible light water splitting; cocatalysts;

Facility: ENE, LMX, Thin Films and Interfaces

Reference: W. Si et al, Phys.Chem.Chem.Phys. 19, 656 (2017)

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