Porous organic materials for photocatalysis
Sunlight is a clean and inexhaustible source of renewable energy. Especially, the visible range of the solar spectrum accounts for 44% of the total energy as opposed to only 3% from the ultraviolet (UV) light. Taking inspiration from Nature, where various chromophores or photocatalysts for converting solar energy into chemical energy have been utilized for millions of years, organic chemists have developed a variety of visible light photocatalysts to mimic the natural process. As a result, many molecular inorganic, transition metal-based complexes or organic dye compounds that absorb significantly in the visible spectrum were intensely studied to harvest solar energy and catalyze organic photochemical reactions. Nevertheless, there are some intrinsic drawbacks associated with these homogeneous systems, such as high cost, toxicity of these rare metals, as well as limited availability and post-reaction purification steps for catalyst removal. The above-mentioned disadvantages have led material scientists to pursue the further development of stable, recyclable, reusable and transition metal-free photocatalysts for organic synthesis.
In recent years, there have been few responses to the acute need of heterogeneous non-metal photocatalytic systems. Among those, conjugated porous polymers, a new class of organic semiconductors combining photoactive p-electron backbone and highly porous properties, have recently emerged as an efficient and stable platform for heterogeneous visible light-promoted chemical transformation reactions such as molecular oxygen activation, selective oxidation of organic sulfides, C-C bond formation, reductive dehalogenation reaction, oxidative hydroxylation of arylboronic acids, visible light-initiated free radical and cationic polymerization, and light-induced hydrogen evolution.
Our research group aims to develop highly porous organic materials as a novel class of metal-free (photo)catalytic systems. We are interested in the study of the interaction between the morphology variation, porosity control, energetic band alignment of this new class of porous organic semiconductors and the their (photoc)catalytic efficiency. Another focus lies on the fundamental development of sustainable synthetic pathways for chemical transformation reactions such as non-metal, visible light-promoted photocatalytic C-C or C-N bond formation reactions, and also light-triggered biomedical applications etc.