State of the art
- Chemical and photochemical stability of the photocatalyst is a limiting factor for the reaction yield, its scale up and a decrease of the associated costs.
- Reaction mechanism is very challenging to determine because of the
complexity of the investigated system and this limits optimisation of the
reaction, as well as design of new photocatalytic pathways.
- Analysis of the photochemical parameters affecting the reaction yield (photon flux, reagent concentrations, energy of the irradiation light) is usually neglected, but it has a strong impact in view of a scale-up.
Scheme 3. Design of improved photocatalysts and investigation of photoreaction mechanism by photochemical and electrochemical study.
Progress beyond the state of the art
- Screening of existing metal-free photocatalysts (4-CzIPN, MesAcr, Eosin) and design of new ones will be performed based on the following parameters (Scheme 3): (i) (photo)chemical stability and recyclability; (ii) long lifetime (microsecond timescale thanks to phosphorescent chromophores or molecules exhibiting delayed fluorescence) of the photoreactive excited states to reduce the amount of sacrificial reagent used and the associated costs.
- A detailed study of the photocatalytic mechanism will be performed by coupling steady-state and time-resolved photochemical measurements under the investigated reaction conditions, as well as electrochemical and spectroelectrochemical analysis.
- The reaction yield will be analysed as a function of the photon flux, reagent concentrations and stepwise injection of reagents in the flow reactors to confine reaction volumes.
- At least two metal-free photocatalysts with high photostability under the reaction conditions and long lifetimes of the photoreactive excited state (>tenths of microseconds) will be developed.
- Photokinetic model of selected photoreactions and successive optimisation of the reaction conditions will be undertaken.
- Based on the results gained by the other partners of the consortium, the electronic properties of the photocatalysts will be optimised.