Fundamentals of photocatalytic water splitting at spinel oxide interfaces

Subproject P11

Obtaining mechanistic insights into photocatalytic processes in their natural aqueous environment is challenging since it is difficult to probe just the interfacial molecules in the presence of the bulk. Moreover, typical reaction timescales are very short, making high time resolution necessary.

The long-term objective of P11 is to unravel the reaction mechanism of photocatalytic processes in real-time directly at the water-catalyst interface, where the reaction is taking place. In the first project period, we focus on photocatalytic water splitting at iron spinel oxide interfaces. The project will benefit from high-quality and well-characterized spinel samples prepared by P04 Parkinson. We will use vibrational spectroscopy to probe only the interfacial molecules. In this way, we study the strength of hydrogen bonds and the orientation of the water molecules, i.e., how water binds to various spinel oxides. Subsequently, photodissociation will be initiated by a laser pulse mimicking sunlight. We will follow the reaction on sub-picosecond timescales by probing the water molecules and potential reaction intermediates and products. The collaboration with theoretical projects helps with data interpretation and fundamental insights into the reaction (P12 Dellago). The water structure and reaction dynamics will be linked to reported efficiencies of the photocatalysts to connect molecular-level details to high catalytic efficiency (P10 Föttinger).

Ellen Backus
PI

Expertise

Our expertise is ultrafast and nonlinear optical spectroscopy, predominantly in the infrared spectral region. We have two femtosecond amplifiers and several optical parametric amplifiers to convert the amplifier’s 800 nm output into other frequencies.

To study the solid-liquid interface, our focus in the TACO project, we will have two time-resolved sum-frequency generation setups, of which one is phase-resolved as well.

Team

Ellen Backus
PI

Harsharan Kaur
PostDoc

Moritz Zelenka
PhD Student

Associates

Martin Buessler
PhD Student

Former Members

Lukas Bogner
Master Student

Publications

2023

Ultrafast Surface‐Specific Spectroscopy of Water at a Photoexcited TiO2 Model Water‐Splitting Photocatalyst

Backus, Ellen H. G.; Hosseinpour, Saman; Ramanan, Charusheela; Sun, Shumei; Schlegel, Simon J.; Zelenka, Moritz; Jia, Xiaoyu; Gebhard, Maximilian; Devi, Anjana; Wang, Hai I.; Bonn, Mischa

Ultrafast Surface‐Specific Spectroscopy of Water at a Photoexcited TiO2 Model Water‐Splitting Photocatalyst

Journal ArticleOpen Access

In: Angewandte Chemie - International Edition, no. e202312123, 2023, ISSN: 1521-3773.

Abstract | Links | BibTeX | Tags: P11

Unravelling the interfacial water structure at the photocatalyst strontium titanate by sum frequency generation spectroscopy

Buessler, Martin; Maruyama, Shingo; Zelenka, Moritz; Onishi, Hiroshi; Backus, Ellen H. G.

Unravelling the interfacial water structure at the photocatalyst strontium titanate by sum frequency generation spectroscopy

Journal ArticleOpen Access

In: Physical Chemistry Chemical Physics, vol. 25, pp. 31471–31480, 2023.

Abstract | Links | BibTeX | Tags: P11

2020

Probing the Mineral–Water Interface with Nonlinear Optical Spectroscopy

Backus, Ellen H. G.; Schaefer, Jan; Bonn, Mischa

Probing the Mineral–Water Interface with Nonlinear Optical Spectroscopy

Journal ArticleOpen Access

In: Angewandte Chemie - International Edition, vol. 60, no. 19, pp. 10482–10501, 2020.

Abstract | Links | BibTeX | Tags: P11, pre-TACO

Surface Charges at the CaF2/Water Interface Allow Very Fast Intermolecular Vibrational-Energy Transfer

Lesnicki, Dominika; Zhang, Zhen; Bonn, Mischa; Sulpizi, Marialore; Backus, Ellen H. G.

Surface Charges at the CaF2/Water Interface Allow Very Fast Intermolecular Vibrational-Energy Transfer

Journal ArticleOpen Access

In: Angewandte Chemie - International Edition, vol. 59, no. 31, pp. 13116–13121, 2020.

Abstract | Links | BibTeX | Tags: P11, pre-TACO

2019

How water flips at charged titanium dioxide: an SFG-study on the water–TiO2 interface

Schlegel, Simon J; Hosseinpour, Saman; Gebhard, Maximilian; Devi, Anjana; Bonn, Mischa; Backus, Ellen H. G.

How water flips at charged titanium dioxide: an SFG-study on the water–TiO2 interface

Journal ArticleOpen Access

In: Physical Chemistry Chemical Physics, vol. 21, no. 17, pp. 8956–8964, 2019.

Abstract | Links | BibTeX | Tags: P11, pre-TACO