The Obligate Mutualism in Metal Nanoclusters

Metal nanoclusters have garnered significant attention owing to their unique physicochemical properties. However, the synthesis of reduced, reactive metal-based nanoclusters, such as reduced Ni nanoclusters, remains challenging because of their intrinsic instability. Herein, we first reported ambient-stable, reduced Ni nanoclusters by subtly engineering the protecting ligands, and particularly revealed a previously unrecognized stabilization mechanism in which two Ni nanoclusters, each difficult to isolate individually, are stabilized through coexistence. Remarkably, the paired clusters remain stable in both the solid and solution phases and exhibit interdependent stability reminiscent of obligate mutualism in biological systems. This finding suggests that weak intercluster interactions can be harnessed to engineer mutually stabilized assemblies, providing access to metal nanoclusters that would otherwise be unattainable. Further studies reveal that the two nanoclusters play complementary catalytic roles and synergistically promote nitrate reduction. Hydrogen spillover between the paired clusters facilitates catalytic turnover, resulting in markedly enhanced activity relative to the individual nanoclusters. These results demonstrate that nanocluster supra-assembly, beyond the specific case of obligate mutualism, can simultaneously enhance stability and functionality. More broadly, this work establishes intercluster assembly as a general strategy for accessing, stabilizing, and optimizing atomically precise nanoclusters, opening new opportunities for the rational design of advanced catalytic systems.