Thermal Decomposition Of Single-source Precursor Research Articles

Solventless Synthesis of Zinc Sulphide Nanoparticles from Zinc Bis(diethyldithiocarbamate) as a Single Source Precursor.

This study explores the synthesis of nanoparticles through the thermal decomposition of single-source precursors, a method gaining popularity due to its low cost, minimal environmental toxicity, rapidity, scalability, and the ability to form nanoparticles with few defects. Zinc ethyl carbamate was synthesized and characterized using 1HNMR and infrared spectroscopy. Its purity was confirmed through microelemental analysis and melting point determination. The melting point of the complex was determined to be 165 °C. The thermogravimetric analyses indicated a one-step decomposition of zinc ethyl carbamate with a decomposition onset of of 200 °C, yielding a stable ZnS residue. Further thermal decomposition led to the formation of wurtzite phase ZnS nanoparticles, as evidenced by XRD. SEM micrographs displayed mixed spherical, and cubic unevenly sized, polydispersed nanoparticles, while EDX revealed approximately a 1 : 1 Zn to S ratio. Estimated band gap from the Tauc's plot gave 3.93 eV and 3.42 eV for the nanoparticles synthesized at 300 and 400 °C respectively. The wide difference in the band gaps may be as a result of the larger particles observed at 400 °C and the deformations in the sample as observed in the SEM.

Calcareous Foraminiferal Shells as a Template for the Formation of Hierarchal Structures of Inorganic Nanomaterials

A microorganism template approach has been explored for the fabrication of various well-defined three-dimensional (3D) structures. However, most of these templates suffer from small size (few μm), difficulty to remove the template, or low surface area, which affect their potential use in different applications or makes industrial scale-up difficult. Conversely, foraminifer's microorganisms are large (up to 200 mm), consist of CaCO3 (easy to dissolve in mild acid), and have a relatively high surface area (≈5 m2 g-1). Herein, we demonstrate the formation of hierarchical structures of inorganic materials using calcareous foraminiferal shells such as Sorites, Globigerinella siphonifera, Lox-ostomina amygdaleformis, Calcarina baculatus or hispida, and Peneroplis planatus. Several techniques, such as thermal decomposition of single-source precursors of metal oxides or sulfides, reduction of metal salts directly on the surfaces, and redox reactions, were used for coating of different shell materials and several hybrid compositions, which possess nanofeatures. Finally, we examined the role of the prepared 3D structures on the reduction of 4-nitrophenol (4-NP), ethanol electrooxidation, and water purification. A remarkable performance was achieved in each application. The hierarchical structure leads to the reduction of 4-NP within several minutes, a 27 mA cm-2 current density peak was obtained for ethanol electrooxidation, and more than 95% of the organic dye contaminants were successfully removed. These results show that using foraminiferal shells offers a new way for designing complex hierarchical structures with unique properties.

Germanium Compounds Containing Ge═E Double Bonds (E = S, Se, Te) as Single-Source Precursors for Germanium Chalcogenide Materials.

New germanium chalcogenide precursors, S═Ge(dmamp)2 (3), S═Ge(dmampS)2 (4), Se═Ge(dmamp)2 (5), Se═Ge(dmampS)2 (6), Te═Ge(dmamp)2 (7), and Te═Ge(dmampS)2 (8), were synthesized from Ge(dmamp)2 (1) and Ge(dmampS)2 (2) using sulfur, selenium, and tellurium powders (dmamp = 1-dimethylamino-2-methyl-2-propanolate, dmampS = 1-dimethylamino-2-methylpropane-2-thiolate). Complexes 1 and 2 were synthesized from metathesis reactions of GeCl2·dioxane with 2 equiv of aminoalkoxide or aminothiolate ligands. Thermogravimetric analysis of complex 1 displayed good thermal stability and volatility. The molecular structures of complexes 2-8 from X-ray single crystallography showed distorted trigonal bipyramidal geometry at the germanium centers. Germanium chalcogenide materials (GeSe and GeTe) were obtained from the thermal decomposition of complexes 5, 6, and 8 in hexadecane. X-ray diffraction patterns exhibited that GeSe and GeTe had orthorhombic and rhombohedral phases, respectively. This study affords a facile method to easily prepare germanium chalcogenide materials using well-designed and stable complexes by thermal decomposition of single-source precursors in solution.

High-pressure high-temperature stability of hcp-IrxOs1−x (x = 0.50 and 0.55) alloys

Hcp-Ir0.55Os0.45 and hcp-Ir0.50Os0.50 alloys were synthesised by thermal decomposition of single-source precursors in hydrogen atmosphere. Both alloys correspond to a miscibility gap in the Ir–Os binary phase diagram and therefore are metastable at ambient conditions. An in situ powder X-ray diffraction has been used for a monitoring a formation of hcp-Ir0.55Os0.45 alloy from (NH4)2[Ir0.55Os0.45Cl6] precursor. A crystalline intermediate compound and nanodimentional metallic particles with a large concentration of defects has been found as key intermediates in the thermal decomposition process in hydrogen flow. High-temperature stability of titled hcp-structured alloys has been investigated upon compression up to 11 GPa using a multi-anvil press and up to 80 GPa using laser-heated diamond-anvil cells to obtain a phase separation into fcc + hcp mixture. Compressibility curves at room temperature as well as thermal expansion at ambient pressure and under compression up to 80 GPa were collected to obtain thermal expansion coefficients and bulk moduli. hcp-Ir0.55Os0.45 alloy shows bulk moduli B0 = 395 GPa. Thermal expansion coefficients were estimated as α = 1.6·10−5 K−1 at ambient pressure and α = 0.3·10−5 K−1 at 80 GPa. Obtained high-pressure high-temperature data allowed us to construct the first model for pressure-dependent Ir–Os phase diagram.

Synthesis of high-quality lanthanide oxybromides nanocrystals with single-source precursor for promising applications in cancer cells imaging

Nanocrystals of lanthanide oxybromides (LnOBrs) with low-phonon energy and high chemical stability are of particular interest for lighting and bioimaging applications. Here, for the first time, we report the synthesis of high-quality LnOBr (Ln=La, Eu, Gd, Tb) nanocrystals using the thermal decomposition of single-source precursors. Moreover, this robust and facile method can be used to synthesize optically active ultrathin EuOBr nanosheets and Eu3+-doped LaOBr nanocrystals with unique luminescence properties. Importantly, for the first time, the application of Eu3+-doped LaOBr nanocrystals in cancer cell imaging has been demonstrated.

Controlled synthesis of metal sulfide nanocrystals by thermal decomposition of single-source precursors

This review briefly summarizes our recent progresses in the controlled synthesis of metal sulfide nanocrystals by a general method based on the thermal decomposition of single-source precursors in solution phase. By controlling the reaction conditions, such as the precursors, capping agent, temperature, solvent, etc., we have successfully prepared a series of metal sulfide nanocrystals with controlled sizes, shapes, chemical compositions and crystal structures. In addition to the synthetic protocols, we also provide a brief account of the responsible mechanism for the formation of metal sulfide nanocrystals. Finally, we summarize the properties and applications of several typical metal sulfide nanocrystals.

In situ synchrotron study of Au–Pd nanoporous alloy formation by single-source precursor thermolysis

We have successfully prepared a face-centered cubic Au–Pd nanoporous structure (NPS) in a one-pot reaction under thermal decomposition of single-source precursor [Pd(NH3)4][AuCl4]2. The precursor employed contains both desired metals ‘mixed’ on the molecular level, thus providing its significant advantages for obtaining alloys. The observation using a high-resolution transmission electron microscope has shown that the nanostructure was composed of interconnected polycrystalline ligaments with an average diameter of 14 ± 3 nm. The measurements made by energy-dispersive x-ray analysis and powder x-ray diffraction (XRD) confirm that the nanostructure consists of Au0.67Pd0.33 alloy. In situ real-time synchrotron XRD was used to study the formation mechanism for Au–Pd alloy NPS. We provide the correlation of control parameters (such as temperature, rate of increase of temperature and gas atmosphere) with the microstructure and phase behavior of bimetallic products. Under reducing conditions (H2 atmosphere) the first step is the formation of alloy nanowires. Finally, bimetallic alloy 3D nanostructure is formed after the complete decomposition of the precursor (100 °C).

Tunable photoluminescence from the visible to near-infrared wavelength region of non-stoichiometric AgInS2 nanoparticles

Non-stoichiometric AgInS2 (AIS) semiconductor particles were synthesized by the thermal decomposition of single-source precursors in solutions of two kinds of primary amines (oleylamine and octylamine). The Ag content in the resulting nanoparticles was controlled by adjusting the chemical composition of the precursor used, in which the mole ratio of Ag+ to total metal ions was varied from 0.1 to 0.7, resulting in the production of non-stoichiometric AIS particles with varying amounts of Ag vacancies. The average size of AIS particles was slightly decreased from 4.3 to 3.8 nm on changing the solvent from oleylamine to octylamine in the preparation, while the particle size seemed to be constant regardless of the content of Ag. On the other hand, the optical properties of AIS particles were considerably modified depending on the Ag content in the particles. The absorption onset was blue-shifted from 750 to 580 nm with a decrease in the Ag content, due to the enlargement of the energy gap of particles. Intense photoluminescence originating from the donor–acceptor pair recombination was observed for each kind of AIS particle and then the photoluminescence peak wavelength was also blue-shifted from 830 to 650 nm, being similar to the behavior of the absorption onset. The maximum photoluminescence quantum yield was ca. 70% for octylamine-modified AIS nanoparticles having a ratio of Ag+ to total metal ions of 0.37, which probably contained the optimum amount of Ag vacancies acting as the sites of donor–acceptor pair recombination with few surface defect sites for non-radiative recombination.

Effective photocatalytic degradation of organic pollutant by ZnS nanocrystals synthesized via thermal decomposition of single-source precursor

2-Aminocyclopentene-1-dithiocarboxylate complex of zinc(II) has been synthesized and found to be an effective single-source precursor for the preparation of ZnS NCs (rod and sphere) by the use of ethylenediamine and hexadecylamine as structure directing solvents. Structural characterizations were carried out using XRD, TEM and BET measurements and the optical properties by UV–Vis and PL spectroscopic techniques. The prepared ZnS NCs show effective photocatalytic activity towards the degradation of Rose Bengal dye (RB) under light irradiation for their probable application in waste water treatment. The degradation mechanism of RB dye under light irradiation is established by terephthalic acid photoluminescence probing technique.

Generalized synthesis of metal sulfide nanocrystals from single-source precursors: size, shape and chemical composition control and their properties

A general and facile method is reported for the synthesis of a wide range of metal sulfide nanocrystals including silver sulfide, zinc sulfide, cadmium sulfide, lead sulfide, bismuth sulfide, tin sulfide, iron sulfide and copper sulfide, etc. This method is based on the thermal decomposition of single-source precursors composed of metal-diethyldithiocarbamate in solution phase. By this method, not only the size and shape but also the chemical composition of the products can be easily controlled. Furthermore, these as-synthesized metal sulfides with different sizes, shapes and chemical compositions exhibit novel optical, electronic and magnetic properties, such as near-infrared (NIR) photoluminescence (PL), strong ferromagnetism and excellent electrochemical properties. We expect that this facile methodology for metal sulfides synthesis can be generalized to other nanocrystals synthesis, and be of high importance to explore the new properties.