Metal-organic frameworks (MOFs)
In recent years, MOFs have shown great potential as photocatalysts, e.g. for hydrogen evolution and CO₂ reduction, as they can combine light-harvesting and catalytic functions with an excellent reactant adsorption capability.
HER process of Ti-MOF
mixed ligand MOFs
– Mechanistic study of MOFs being as photocatalyst
The ligand to metal charge transfer (LMCT) process is considered as a unique advantage of photoactive MOFs. To verify the LMCT mechanism as well as to clarify the effect of ligand functionalization, isoreticular MOFs with different ligands are synthesized. The charge-separation and charge-transfer during the photocatalytic process have been focused.
Another research interest is the photoactive redox transition within the metal cluster under light irradiation, e.g., between Ti³⁺/Ti⁴⁺ in the Ti-based MOF.
– Selective ligand removal
In dynamic processes, and especially in liquid phase catalysis, the accessibility of active sites becomes a critical parameter, as the reactant diffusion is often limited by the inherently small micropores of MOFs.
One promising strategy to overcome this challenge involves selective ligand removal in mixed-ligand MOFs, which introduces additional pores that can facilitate reactant diffusion to the active sites. This process also yields unsaturated metal sites that may act as new active sites for (photo) catalysis.
A series of mixed-ligand MOFs of interest to photocatalysis are investigated and the selective ligand removal upon thermolysis is characterized with a range of the state-of-the-art techniques. Then the effects of ligand removal on the photocatalytic properties are evaluated.