Heterogeneous photocatalytic organic synthesis: state-of-the-art and future perspectives

Heterogeneous photocatalytic systems have the potential to provide a green organic synthesis route for a number of industrially important chemicals. Issues remain with lack of selectivity. In this paper, a review is presented on achievements in this field. Parallels are drawn between systems optimised for heterogeneous photocatalytic organic degradation and heterogeneous catalytic organic synthesis. There is much fundamental knowledge that is still missing in this field of research. Parameters that can be manipulated are reaction solvent, pH, photon energy, chosen photocatalyst and its specific properties, and perhaps the use of more than one photocatalyst. Screening of photocatalysts for specific reactions and adapting the reaction conditions may achieve the best selectivity. Unlike the popular case of photocatalysts for organic degradation, the photocatalysts for organic synthesis should be highly customised on a case-by-case basis. Attention should be given to photocatalysts with the potential to be activated by the visible light spectrum, in order to achieve cost effectiveness of the heterogeneous photocatalytic organic synthesis.