Research

The LightChEC research program is structured in seven interdisciplinary research topics, which are each lead by a different research group:

Photocatalytic Water Reduction WRC and Photosensitizers

Lead by Prof. Roger Alberto.

Our group work on photocatalytic water reduction focuses on the design and synthesis of metal-based water reduction catalysts and photosensitizers. Spectroscopic-, electrochemical- and photocatalytic measurements are combined to unravel the reaction sequence in solar watersplitting. Knowledge of rate limiting steps is key in the development of new systems, whereas measuring the stability of the systems allows the rational design of new catalysts. In 2011 we presented the first photocatalytic water reduction system in pure water (B. Probst et al. Inorg. Chem. 2011, 50, 3404). Currently we are working on catalytic H2 formation with a reversible electron donor and novel ligands. If properly designed, this triad system can be coupled to water oxidation, the second crucial step in solar light to chemical energy conversion.

Visible-Light-Driven Water Oxidation Catalysts WOC

Lead by Prof. Greta Patzke.

Our goal is the development of robust, environmentally friendly and low-cost water oxidation catalysts (WOCs) for visible-light-driven water splitting processes. Based on our experience in transition metal oxide research, we synthesize and test molecular WOCs (especially polyoxometalates and cubanes) as well as nanostructured heterogeneous WOCs. In complementary collaborations with other UFSP teams, we aim for catalytic structure-activity relationships and pathways in order to optimize WOC design for solar energy applications.

Computation of Dynamic Properties of Water Oxidation 

Lead by Prof. Juerg Hutter.

Our scientific expertise and concepts consist in the simulation of the structures and electronic properties of photosensitizers and catalysts in solution and at interfaces. Elucidation of reaction mechanisms is achieved using free energy mapping.

Timeresolved Spectroscopy of Artificial Photosynthetic Systems

Lead by Prof. Peter Hamm.

Transient UV-VIS and IR spectroscopy as well as 2D IR spectroscopy is applied to investigate structure and dynamics of homogeneous and heterogeneous artificial photosynthetic systems.

Surfaces

Lead by Prof. Jürg Osterwalder.

The objective is to provide mechanistic insight into how novel catalyst molecules and photosensitizers, developed within the UFSP for the homogeneous water splitting route, might perform when adsorbed on a solid surface. For this purpose, a small set of model systems will be established, including at least one for each type (WRC, WOC, PS), and characterized in terms of adsorption geometry and bonding, charge redistribution upon photoexcitation and excited state life times. Such knowledge will assist in designing strategies for building a heterogeneous system required for a continuously operating visible-light-driven water splitting process.

Surfaces / H2 and CO2 Storage and Conversion

Lead by Prof. Karl-Heinz Ernst

Our scientific expertise and concepts cover investigations of elementary steps of CO2 activation / hydrogenation over well-defined model catalysts; investigation of the mechanism of CO2 reduction on metal hydrides by means of XPS- and IR-spectroscopy; and the thermodynamics of the reaction.

Photoelectrochemical Water Splitting with Thin Film Semiconductors

Lead by Prof. David Tilley.

Our group is interested in fabricating thin film light absorbers that generate a high photovoltage for water splitting. Different types of catalysts (thin film, nanoparticulate, molecular) are employed to minimize overpotentials and to maximize water splitting efficiency. The materials are characterized with a variety of electrochemical and physical techniques, which aid in the improvement of these films. The goal is to have an overall water splitting system using only visible light as the energetic input.

Electronic Structure of materials for solar-water splitting

Lead by Dr. Andreas Borgschulte

In our lab we are developing a range of techniques for studying solar water splitting systems. Namely, for analysis of heterogeneous catalytic reactions, quasi ambient pressure XPS analysis is realised using a membrane device, which is exposed to H2O at ambient pressure on one side and UHV for analysis on the other. For homogeneous solar water splitting systems another technique, time resolved magneto-optical spectroscopy (trMOKE), was recently developed. The technique probes magnetic properties of materials, which are directly related to the electronic properties and thus serve as a probe for the changes induced by light in photo-catalytic reactions. Apart from empirical investigations, an important task is the modelling of the data. The work includes the definition of key parameters which are accessible by experiment such as the exchange current by electrochemical measurements and the (shift of the) d-band center by XPS, and the correlation between them aiming at a rational description of the mechanisms involved.