Enhanced photocatalytic CO2 reduction over heterogenized rhodium complex within microporous polymers
Résumé
In the past decade, microporous polymers, including both porous organic polymers and metal-organic frameworks (MOFs), have received increasing attention as they combine the advantages of high surface area and high pore volume with tunable structures and easy functionalization. The materials are well suited for technologically important applications such as gas storage and gas separation. They also have a high potential in some of the most challenging areas of chemical research, including heterogeneous catalysis, drug delivery or sensing. Amongst the catalytic applications, photochemical reactions such as water splitting and CO2 reduction are of tremendous importance as routes to renewable energy sources.[1]
Recently our group reported the incorporation (heterogenization) of a rhodium based catalyst for the photochemical CO2 reduction within the MOF UiO-67. Using this catalyst, formate was obtained as the only carbon-containing product with a turnover number of ~25 after 4 h.[2]
In this contribution we present novel bipyridine containing porous organic polymers as promising class of host materials for catalytically active rhodium complexes for carbon dioxide reduction.
The active rhodium center can easily be integrated into the host by post-synthetic infiltration with a suitable precursor. The integration into the flexible porous polymer allows for a good accessibility of the active centers. Furthermore, the catalyst remains stable under the basic conditions of the photocatalysis and the productivity of formate remains constant over at least five cycles.
The porous organic polymers-based catalysts exhibit high production rates R of formate. The R, TON and TOF values exceeded the best literature-known heterogeneous systems under similar conditions by at least one order of magnitude (up to R 3.7 ± 0.2 mmol/h/gcat as compared to < 0.5 mmol/h/gcat[2-3]).
Literature:
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