Assembling Giant Nanoclusters as Heterogeneous Catalysts for Effectively Converting CO₂ to CO Under Visible Light

Heterometallic lanthanide-transition metal (3d-4f) nanoclusters with well-defined structures and multiple active sites are excellent vehicles for achieving efficient catalysis and studying heterometallic synergism. In this work, two closely related yet different high-nuclearity nanoclusters, 72-nuclear {Ni₂₈RE₄₄} (1, RE = Pr, Nd, Sm, Eu, and Gd) and 111-nuclear {Ni₄₈La₆₃} (2), are synthesized using a mixed-ligand strategy. Importantly, the crystal solids of these giant coordination clusters are insoluble when soaking in H₂O/CH₃CN and can be used as heterogeneous catalysts for visible-light-driven catalytic conversion of CO₂ to CO. Cluster 2 exhibits a maximum CO production rate of 4800 µmol g^-1 h^-1 and a CO selectivity of 92% over H₂. Furthermore, the catalytic properties are investigated of different rare earths in the cluster 1 series, found that 1-Eu exhibited superior catalytic performance under identical conditions, likely due to the lower reduction potential of the europium ions. This study represents the first report of 3d-4f heterometallic nanoclusters as heterogeneous catalysts for photocatalytic reaction and provides a reference for the study of high-nuclearity 3d-4f nanoclusters as catalysts for photocatalytic reduction of CO₂ to CO.