Biomimetic Cu₄ Cluster Encapsulated within Hollow Titanium-Oxo Nanoring for Electrochemical CO₂ Reduction to Ethylene

The construction of biomimetic clustercatalysts with metalloenzyme-likeactive sites may open an avenue for the challenging transformationof greenhouse gases (e.g., CO2) to high-value chemicals.Cu-enzymes occur in all three biological kingdoms, with Cu-Z clusters serving as representative reaction sites that catalyzechallenging transformations. However, artificial Cu clusters withanalogous Cu-Z structures and high stability are still rare.In this work, we have successfully adopted a Ti-9-oxo nanoringas an inorganic templating scaffold to isolate a small Cu-4 cluster, which can be regarded as a atomically precise bioinspiredcluster with metalloenzyme-like catalytic sites (Cu-Z).Importantly, Cu ( 4 ) @Ti ( 9 ) displays high selectivity for the electrocatalyticreduction of CO2 to C2H4 (FE: 47.6 +/- 3.4%) at 400 mA cm(-2) and good catalytic durability(8 h). The bioinspired Cu ( 4 ) @Ti ( 9 ) not only represents the firstexample of Cu cluster directly encapsulated by a metal-oxo shell butalso opens the CO2 electroreduction to ethylene applicationsof atomically precise metallic clusters.