Controllable synthesis of platinum diselenide (PtSe2) inorganic fullerene

Abstract

Layered transition metal dichalcogenide (TMD) crystals in reduced dimensions have exhibited a wide range of extraordinary physical and chemical properties spanning from exotic quantum phenomena to unusually superior chemical reactivity. Their anisotropic van der Waals (vdW) bonding nature enables them to commonly possess two-dimensional (2D) structures which have been rigorously investigated recently. Nonetheless, TMD crystals in quasi zero-dimensional (0D) forms, i.e., TMD fullerenes, have not been explored in depth from the perspective of reproducible synthesis and process–structure correlation. Herein, we report a controlled synthesis of inorganic fullerene platinum diselenide (PtSe₂) via a thermal selenization of Pt nanostructured precursors. We identified a conversion of Pt nanocubes to PtSe₂ “onion-like” fullerenes, dictated by a well-defined isotropic volume expansion. Extensive transmission electron microscopy (TEM) inspections revealed that there exists a certain size-dependency which leads to the preferable growth of PtSe₂ fullerenes over 2D PtSe₂ platelets. The underlying principle for this size-dependent growth is discussed in the context of surface energy minimization. Furthermore, the PtSe₂ fullerenes were verified to possess a large degree of unsaturated dangling bonds as well as internal strain, verified by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) as well as a geometric phase analysis (GPA). This study sheds light on synthesizing a wide range of TMD-based fullerenes which will foster the discovery of novel physical and chemical properties in quasi 0D material systems.