Heterogeneous molecular rhenium catalyst for CO2 photoreduction with high activity and tailored selectivity in an aqueous solution

The effective molecular-catalyst-based device that converts CO2 to value-added products is of significance but challenging. Herein, utilizing organosilica nanotubes as the solid chelating ligands, we successfully construct heterogeneous molecular rhenium catalysts for efficient CO2 photoreduction to CO. The nanotube framework compositions and the microenvironment of the rhenium catalysts are finely regulated, aiming to enhance the catalytic selectivity and activity in water-containing systems. By adjusting bipyridine amounts and capping the surface silanols, the preferential adsorption for CO2 over H2O around the active sites is realized. Relative to that of the unmodified catalyst, the CO selectivity increased greatly from 53% to 94% in water/acetonitrile. Furthermore, the heterogeneous molecular catalysts exhibit a total turnover number that is nine times higher than the corresponding homogeneous one (134 versus 15). Using in situ infrared spectroscopy and density functional theory calculations, a reasonable mechanism for high CO selectivity in the presence of H2O is demonstrated.