Organometallic Synthesis, Structure Determination, Shape Evolution, and Formation Mechanism of Hexapod-like Ternary PbSe_xS_1–x Nanostructures with Tunable Compositions

Abstract

The fabrication of hexapod-like ternary PbSexS1-x nanostructures has been reported via an alternative organometallic route from reaction of Pb(II) salt with triphenylphosphine selenide (Ph3PSe) and dibenzyl disulfide (DBDS) in dibenzylamine (DBA) with addition of oleic acid (OA) at 260 °C. The shape, structure, and composition of the nanostructured hexapods are investigated and determined by techniques of XRD, SEM, TEM, Raman, HRTEM, SAED, XPS, EDX, and HAADF-STEM, and the obtained ternary nanostructured hexapods are of typical rock salt phase with Pb-rich features without phase separation, and their compositions could be systematically regulated by facile variations of reaction parameters. Investigations reveal that the successful fabrication of the ternary hexapods with tunable compositions is resulted from the effective selection of Se and S sources of Ph3PSe and DBDS that have similar reactivity in the current reaction system along with small lattice mismatch between the two end members of PbSe and PbS. Generally, the relations between the composition and lattice parameters for the ternary nanostructures obtained in DBA with varied addition of OA exhibit linear slops that are consistent well with Vegard's law. Interestingly, intensive investigations show that the nanostructures are mainly gradiently alloyed nanostructures with somewhat chalcogen-element segregations or disorders rather than homogeneously alloyed solid-state solutions due to kinetic limitation for short reaction time even though thermodynamics is feasible in the system, and also, high concentration of S element in the feedstocks tends to relative high density of disorders in the ternary nanostructures. Based on the revealing of the formation mechanism for the nanostructures with varied microstructures, the ternary PbSexS1-x hexapods can be tuned from gradient alloys with segregations to approximately homogeneous via enlongating reaction time. In addition, the photolysis of the nanostructures to lead oxysulfate and oxyselenate species is evidenced at ambient condition via Raman detection although they are stable at -190 °C.

PbS x Se1−x thin films from the thermal decomposition of lead(II) dodecylxanthate and bis(N,N-diethyl-N′-naphthoylselenoureato)lead(II) precursors

“…Both theoretical and experimental determination of the dependence of band gap values on composition of PbS x Se (1-x) have been reported to show a linear relationship between the band gap energy of thin film and the composition ( Fig. 9) [10,14,40].…”

“…Chugaev elimination to yield the corresponding metal sulfides [1,2]. Most reports on the syntheses of nanoparticulate PbS x Se (1-x) concern hot injection methods [9][10][11][13][14][15][16], flash evaporation [17], thermal evaporation [18] or vacuum evaporation [12] techniques, which all require moderately harsh conditions including high vacuum, expensive apparatus and very toxic starting materials.…”

Unconventionally anisotropic growth of PbSe nanorods: Controllable fabrication under solution-solid-solid regime over Ag2Se catalysis for broadband photodetection

“…S7 in the ESM) rather than the media of OAm and OAc (Fig. S10 in the ESM) although it is revealed that both OAm and OAc would influence on the growth of PbSe nanocrystals with different shapes based on the selective absorption on crystals planes [66,67].…”

Rock-Salt MnS0.5Se0.5 Nanocubes Assembled on N-Doped Graphene Forming van der Waals Heterostructured Hybrids as High-Performance Anode for Lithium- and Sodium-Ion Batteries

“…However, there could be an asymmetric feature of diffraction peaks detected in the magnified pattern (Figure S1), revealing a detectable decrease in crystallinity. The decrease in crystallinity often results from the possible generation of segregations in the disordered solid-state solutions including the present MnS 0.5 Se 0.5 nanocubes grown at relatively low temperatures, which is similar to the ones in PbSe x S 1– x nanocrystals via nonequilibrium growth, especially along with point defects, relevant to distortion and disorder within MoSSe, MoS 2(1– x ) Se 2 x , and CdTe/CdS. ,, The XRD pattern in blue color shows the result obtained for N-doped graphene with the (002) diffraction peak. As for the hybrid sample, the XRD pattern (in orange) reveals the presence of diffraction peaks for both nanocubes and N-doped graphene, which proves that the MnS 0.5 Se 0.5 nanocubes successfully anchored onto N-G.…”

“…As can be witnessed in the HAADF-STEM image of Figure 3b, some partial areas with lower contrast suggest that there are segregations remained in the nanocubes. 38 This uneven alloying had been reported to be a common phenomenon in the solid-state solution of metal sulfides and selenides due to a fast growth at relatively low temperatures, which is related to the generation of distortions and vacancies, thus improving the electrochemical performance. 32,44,45 The nanoscale dislocations can be further confirmed from the magnified HAADF-STEM image (Figure S5).…”