Tuning of Ionic Second Coordination Sphere in Evolved Rhenium Catalyst for Efficient Visible Light-Driven CO2 Reduction.

Developing an efficient and easy-to-handle strategy in designing catalyst for CO 2 reduction into CO by harnessing sunlight is a promising project. We present here a facile strategy to design of ionic secondary coordination sphere modified Re catalyst for photo-reduction of CO 2 to CO by visible light. By adding ionic liquids or tuning different ionic secondary coordination sphere, we discover outstanding optical property, other than CO 2 absorption ability or the ability to dissociation of chloride anion , is the prerequisite for catalyst designing. Accordingly, a novel Re catalyst ({Re[BpyMe(tris(2-hydroxyethyl)amine)](CO) 3 Cl}Br, Re-THEA ) is designed, screened, thus resulting in a relative high quantum yield (up to 34%) for visible light-induced CO 2 reduction with single-molecule system. DFT calculations, combined with experimental outcomes, suggested the pendent ionic tris(2-hydroxyethyl)amino ( THEA ) group on Re-THEA can enhance visible light absorbance, stabilize reaction intermediates and suppress the Re-Re dimer formation.