A rhenium catalyst with bifunctional pyrene groups boosts natural light-driven CO2 reduction

Developing effective sunlight-driven systems for CO2 reduction is one of the most promising subjects from the perspective of sustainably producing solar fuels. Herein, we develop a strategy to boost CO2 reduction performance by enhancing intermolecular electron transfer efficiency and visible light-absorption ability by introducing bifunctional pyrene groups on the ligand. This catalyst exhibits high-efficiency performance for natural light-powered CO2 reduction (TONCO up to 350 +/- 36, phi(CO) up to 46.6 +/- 3%). This is the first report on using a single-molecule photocatalyst for CO2 reduction under natural conditions. Through the combination of experimental results and DFT calculations, the appending pyrene groups have been proven to promote the catalyst's ability to harness visible light as well as facilitate electron transfer (ET) through intermolecular pi-pi interactions. Due to the accelerated intermolecular ET, TONCO can be further boosted up to 1367 +/- 32 in the presence of the ruthenium photosensitizer. Moreover, an enhancement in CO2 electroreduction performance can also be observed for the pyrenyl-functionalized rhenium catalyst further highlighting the versatile applications of this methodology.