Manipulation of Precursor Reactivity for the Facile Synthesis of Heterostructured and Hollow Metal Selenide Nanocrystals

Abstract

We present a one-pot synthesis of nanocrystal heterostructures containing metal selenide cores shelled with tungsten-based metal selenides. This synthesis is enabled by the use of oleic acid as a W-coordinating ligand, which inhibits W reactivity and allows for the formation of core nanocrystals prior to W-based selenide secondary growth. As a case study, we show that high amounts of oleic acid lead to slower, edge-preferred growth of WSe2 on Ni3Se4, whereas lower amounts of oleic acid lead to uninhibited growth of WSe2, fully covering the Ni3Se4 nanocrystals. The Ni3Se4 nanocrystal cores can readily be removed to access hollow WSe2 nanocrystals. The manipulation of W-precursor reactivity can be extended to form Co3Se4/WSe2, Cu2–x Se/Cu2WSe4, and Cu2WSe4/WSe2 core/shell heterostructures. These results demonstrate the exploitation of ligand coordination to enable easy, solution-phase syntheses of exotic or complex nanostructures.

Colloidal Synthesis of Cu–M–S (M = V, Cr, Mn) Nanocrystals by Tuning the Copper Precursor Reactivity

“…Materials chemists have delved into the synthesis of copper-based multinary nanomaterials in response to an increasing demand for novel properties serving applications, which span from energy to biotechnology. − One notable example of such intense research is represented by copper-based chalcogenide nanocrystals (NCs), such as the Cu-III-VI, Cu-IV-VI, and Cu-V-VI families, whereby superior control over their structure and composition has been achieved by means of colloidal chemistry. − As a result, their physicochemical and functional properties have been investigated and exploited for more than two decades. − However, the synthetic library of copper-based multinary NCs is far from being complete. Indeed, if all the possible chemical substitutions and structural modifications attainable in complex compositions are taken into account, one soon realizes that there is still plenty of room for the discovery of new materials.…”

Highly Crystalline Hollow Toroidal Copper Phosphosulfide via Anion Exchange: A Versatile Cation Exchange Nanoplatform

“…To successfully diversify multianion material systems, it is necessary to develop synthetic methodologies to modify existing anion frameworks at mild conditions, without sacrificing the original structural motif and crystallinity. We noticed that tris(diethylamino)phosphine (TDP) undergoes a transamination reaction with oleylamine (OAm) to produce active P precursors for the formation of InP quantum dots and various transition metal phosphides including Cd 3 P 2 , Zn 3 P 2 , Co 2 P, CoP, and Ni 2 P. 14,15 Because the functional groups of the precursor influence the reactivity of the precursor, 16,17 the adoption of transaminated TDP as an active P precursor might allow the kinetically controlled anion mixing in nanostructures under relatively mild reaction conditions, which has not been feasible with other P-donating precursors. Moreover, the similarity between anion frameworks of Cu 2 S and Cu 3 P elevated the chance of successful anion mixing between S and P; the structural motif transfer might be more efficient between the analogous anionic frameworks.…”

Molecular Decomposition Routes of Diaryl Diselenide Precursors in Relation to the Phase Determination of Copper Selenides

“…There are numerous known phases of copper selenides with several polymorphic groups. ,,− Δ G f follows the trend that increasing copper richness increases thermodynamic stability. Krutaite ( p- CuSe 2 ) has a cubic pyrite-like structure, and a hexagonal marcasitic polymorph, petřı́čekite, is known ( m -CuSe 2 ). , All three structures of klockmannite (CuSe) (α-, β-, γ-) have alternating Se – and Se 2 – close-packed layers and coppers in T d holes and in trigonal planes, respectively .…”

“…Guo et al observed zinc blende vs wurtzite polymorphism in CdSe using these two reagents, again citing the difference in their BDE as a main contributing factor to the different phases . Geisenhoff et al changed the ratios of precursors with different reactivities, including Ph 2 Se 2 , to synthesize new heterostructures of WSe 2 . Finally, Lord et al found that at high temperatures for short times (220–250 °C under 30 min), a new weisseite-like (Cu 2– x Se) phase forms from the reaction of Ph 2 Se 2 , Cu­(acac) 2 , and OLAM before forming the more common berzelianite (Cu 1.8 Se) …”