Carbon materials for solar fuel production

Diamond materials for CO2 reduction

 Diamond materials have been shown to be a potential source of solvated electrons enabling CO₂ reduction to fine chemicals in aqueous medium. Diamond being a wide bandgap semiconductor, the challenge is to enable the absorption of visible light and several approaches based on doping, surface functionalization and nanostructuration are currently under investigation. We are applying soft X-ray spectroscopies to probe the impact of the diamond material modification on its electronic properties.

Furthermore, a better understanding of the diamond-water interface is required to optimize electron emission in aqueous environment. To this aim, we use soft X-ray absorption and FTIR spectroscopies to probe the hydrogen bond network of water molecules close to nanodiamonds [1].

We are also investigating the electronic processes leading to the emission of solvated electrons under UV illumination using transient absorption and time-resolved photoemission spectroscopy on nanodiamond dispersions in water and ionic liquids. More details on the methods are available here.

Finally, we are also developing methods to probe in operando the electrochemical conversion of CO₂ to fuel using soft X-ray absorption spectroscopy at the synchrotron BESSY II using an electrochemical flow cell.

This work is funded by the H2020 European project DIACAT.

Polymeric carbon nitride for water splitting

Carbon nitride is another type of carbon nanomaterials attracting a large interest in the field of solar fuel production, in particular for water splitting. Using X-ray absorption and FTIR spectroscopies, we are investigating the electronic and chemical structure of carbon nitride photocatalysts to identify potential active sites for efficient H₂ generation from water molecules in particular [2].

Laser-based time-resolved spectroscopies are also applied to understand the photoexcitation process of polymeric carbon nitride. More details are available here.