Transition Metal-Based Thiometallates as Surface Ligands for Functionalization of All-Inorganic Nanocrystals

We report a new family of inorganic ligands, namely, transition metal-based thiometallates, for the surface functionalization of colloidal nanocrystals (NCs). We synthesized Pt-, Fe-, Co-, and Ni-based thiometallates, in which transition metal ions were complexed with polysulfides. These inorganic anions easily exchanged the surface organic ligands of various nanocrystals of metal, semiconductor, and oxide materials, without affecting the NCs' primary structural and optical characteristics. Furthermore, upon heating, these complexes were decomposed and transformed into crystalline phases of metal sulfides or pure metals, accompanied by the evaporation of S. Based on this effect, we selectively synthesized homogeneously distributed atomic Pt clusters or Pt nanoparticles on Fe₃O₄ nanomaterials by heating thioplatinate-capped Fe₃O₄ NCs. As a model application, we tested the prepared Pt-functionalized Fe₃O₄ nanomaterial as a heterogeneous catalyst for CO oxidation reaction and Pt-Fe₃O₄ catalysts exhibited the high turnover frequency due to the homogeneous distribution of atomic Pt over Fe₃O₄ and the corresponding strong metal-support interaction. This approach opens up a new avenue to functionalize nanocrystals for catalytic applications.