Photocatalysis-based applications that have made it to the market nearly always rely on titanium dioxide (TiO2) as the catalyst. One of the main limitations of this material is its relatively large bandgap energy (ca. 3.2 eV). This implies UV light is required to overcome the bandgap and generate charge carriers that can initiate the photocatalytic degradation pathway. Therefore viable photocatalytic applications running on solely solar light irradiation are scarce to non-existent, as UV only contributes to ca. 4% of the total solar flux on earth. A possible solution to overcome this problem, is coupling the photocatalyst with noble metal nanoparticles (mostly gold and/or silver) that display surface plasmon resonance effects. Surface plasmon resonance (SPR) can be defined as an energetic collective oscillation of free conduction band electrons of the metal nanoparticles. Boldly stated, such plasmonic nanostructures are capable of capturing solar light energy, and transfer it to the photocatalyst. It is a big challenge to understand the precise interaction between these plasmonic nanoparticles and the photocatalytic substrate they are in contact with. The DuEL team therefor aims to understand the physico-chemical interactions on a fundamental level (e.g. by EPR, in-situ FTIR, etc.), while at the same time investigating the application potential of such nanostructures.
Apart from the preparation of photocatalytic materials, our group has developed know-how on coating formulations, required to immobilize these catalysts on a substrate. Immobilization as self-supporting ceramic foams is also one of our achievements.
All (photo)catalysts, (as well as adsorbents) are tested in a customised gas test setup. Various test gases can be accurately dosed to the system (e.g. NOx, ethylene, acetaldehyde, methane and CO2, as well as vapours of any organic liquid with low vapour pressure). Reagents and reaction products can be analysed both on-line as well as off-line by FTIR, GC-FID, Quantum Cascade Laser spectroscopy and a wide variety of specialized gas sensors.