Heterogeneous Photocatalysis

Prof. Jennifer Strunk 

It would be a milestone in chemical energy storage if the reduction of CO2 to methanol or methane, or the splitting of water for the generation of hydrogen, could be implemented with just the light of the sun as energy source. Yet, no ecologically and economically feasible photocatalytic process for the industrial scale is available, in spite of almost 40 years of research. We aim to provide detailed understanding of the underlying fundamental photophysical, catalytic, and electrochemical processes. This insight can then serve as a basis for the development of improved photocatalysts and devices viable for large-scale applications.

Focus is put on semiconducting oxides, starting from TiO2 and ZnO as well-known photocatalyst reference materials. Multiple spectroscopic tools and photoelectrochemical characterization is used to study optoelectronic and catalytic properties, and to follow charge carrier dynamics. It is the aim to clearly identify exactly those structural and electronic properties of the photocatalyst which are responsible for high photocatalytic activity. In all of our studies, it is of utmost importance to perform all experiments under conditions of highest achievable purity. CO2 and H2O are thermodynamically extremely stable, so any other reactant (e.g. impurities in reactor or catalyst) may potentially react faster to apparent products. Most modern tools of trace gas analysis (GC, QMS) allow us to quantify any component of the whole product distribution and to close the mass balance. Another important aspect of our work is the development and testing of new laboratory scale reactors for reliable photocatalytic studies.

The complexity of the challenge is addressed by research groups with different research aims: