A Doughnut‐Like Eu30 Catalyst for CO 2 Photoreduction with Turnover Numbers Over Ten Million

Abstract Polynuclear metal clusters can be potentially high‐performance catalysts for the CO 2 reduction owing to the unique spatial structures among multiple active centers. Herein, two 30‐nuclear doughnut‐like lanthanide clusters ( Eu30 and Dy30 ) were synthesized via in situ tandem reaction following a stepwise annular growth mechanism. In contrast to the Dy‐based analog, Eu30 serves as a high‐performance catalyst in visible‐light‐driven CO 2 ‐to‐CO conversion with 98% selectivity and a record‐high turnover number reaching 1.720 × 10 7 , a rare case with only lanthanide metals as the active centers. Experimental and computational results indicate that the excellent performance of Eu30 , as the first example of pure lanthanide cluster catalyst, can be attributed to its high redox activity with an appropriate LUMO energy level.