Transformation of Active Sites on Cobalt Sulfide Nanoclusters With Similar Nuclearities.

Reduced cobalt sulfide nanoclusters are promising materials; however, their synthesis has long posed significant challenges due to the high reactivity of both cobalt and sulfur. Furthermore, the respective influence of cobalt and sulfur on the properties remains unknown. Herein, we introduce a dual-ligand strategy to successfully synthesize three such nanoclusters with atomic precision. This strategy not only enhances the stability but also modulates both structural dimensions and surface ligand distributions, resulting in distinct catalytic activities and unexpected active site interconversion among cobalt, thiolate sulfur, and bare sulfur in the as-obtained cobalt sulfide nanoclusters. More novel findings such as "habitat segregation" and ligand mutual deletion further demonstrate the modulation diversity of the dual-ligand strategy. Due to the structural integrity maintained during catalysis, our work clarifies that cobalt sulfide itself is intrinsically active for catalysis. The identification of thiolate and bare sulfur active sites provides guidance for the catalysis performance improvement of cobalt sulfide nanoclusters; the novel finding that the dipole moment direction or coordination number correlates with the active site, offers an intrinsic spatial descriptor for the catalytically active sites of cobalt sulfide nanoclusters. Overall, this work has important implications for the synthesis, modulation, and structure-property correlation of cobalt sulfide nanoclusters.