Artificial Photosynthesis - Photoelectrochemistry

In natural photosynthesis, plants use solar energy to convert carbon dioxide and water to carbohydrates. Photosynthesis thus comprises two processes which are among the largest challenges for mankind, namely the long-term storage of renewable energy and the reduction of CO2 in the atmosphere. The efficiency of natural photosynthesis is, however, quite poor.

Artificial photosynthesis aims at mimicking the basic energy conversion processes in the plant, but with inorganic adapted devices which allow for a substantially higher efficiency.

One approach is the photoelectrochemical reduction of CO2 into fuels and basic chemicals which has the potential to become a cornerstone of an energy economy solely based on renewable energies. In our research we try to identify suitable surface modifications of silicon photoelectrodes for an efficient reduction of CO2 via heterogeneous catalysis. The modifications investigated fall into two main categories, firstly the functionalization of the silicon surface with covalently bound organic layers, and secondly the fabrication of metal nanostructures (gold and copper) in contact with the silicon substrate. In parallel, we are interested in the detailed reaction mechanism of CO2 reduction on both, functionalized silicon electrodes and simple metal surfaces as model systems. Experimentally we characterize our functionalized surfaces with surface science tools (XPS, EC-STM, ATR-FTIR) and examine the CO2 reduction reactions using sophisticated product analysis methods (GC, HPLC, DEMS)

Exemplary reaction path for the conversion of CO2 into methane at a copper nanoparticle.
Photoelectrolysis cell with gold electrode.