Improvement of CO<sub>2</sub> Reduction Photocatalysis\nof a Ru(II)–Re(I) Complex and Carbon Nitride Hybrid by Coadsorption\nof an Os(II) Complex Photosensitizer

Photocatalytic CO<sub>2</sub> reduction has attracted attention\nas a prospective technology for addressing global warming and the\nreduction in fossil fuel resources. Hybrid photocatalysts comprising\na visible light-absorbing semiconductor and a supramolecular photocatalyst\nwith photosensitizer and catalyst units in one molecule have been\ndeveloped for CO<sub>2</sub> reduction. As an example, a hybrid of\nTiO<sub>2</sub>-loaded polymeric carbon nitride (PCN) and a Ru(II)–Re(I)\n supramolecular photocatalyst (<b>RuRe</b>/TiO<sub>2</sub>/PCN)\nworks as a CO<sub>2</sub> reduction photocatalyst in the presence\nof triethanolamine (TEOA) to give CO with a high selectivity. However,\nits durability is low, and the maximum turnover number of CO formations\n(TON<sub>CO</sub>) is less than 100. In this study, a system was constructed\nwith coadsorption of an Os(II)-complex photosensitizer (<b>OsP</b>) on the surface of <b>RuRe</b>/TiO<sub>2</sub>/PCN to improve\nthe low durability of the hybrid photocatalyst by promoting a more\nrapid electron supply to the Re catalyst unit of <b>RuRe</b>. The coadsorption of <b>OsP</b> increased the TON<sub>CO</sub> of <b>RuRe</b>/TiO<sub>2</sub>/PCN to 239.