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.