Single-source Molecular Precursor Research Articles

Electrochemically Deposited Nickel Oxide from Molecular Complexes for Efficient Water Oxidation Catalysis.

A facile method for the electrodeposition of amorphous nickel oxyhydroxide is described and discussed in which well-defined nickel complexes with pyridinedimethanol ligands are employed as single-source molecular precursors. No buffering agent is required to assist the anodic deposition process. The deposited nickel oxyhydroxide shows high robustness and efficiency for electrocatalytic water oxidation.

Enthralling Adsorption of Different Dye and Metal Contaminants from Aqueous Systems by Cobalt/Cobalt Oxide Nanocomposites Derived from Single‐Source Molecular Precursors

AbstractThe cobalt/cobalt oxide nanocomposites (Co/CoO NCs), NC‐1 and NC‐2 were synthesizedfrom our recently reported single‐source molecular precursors (SSMPs) [Co(hep‐H)(H2O)4]SO4, (1) and [Co(hep‐H)2(H2O)2](NO3)2, (2), [hep‐H= 2‐(2‐hydroxylethyl) pyridine], respectively, via wet‐chemical reduction method. Our purpose was to study the effect of different counter anions (i. e. SO42− and NO3−) of precursors on the surface properties of synthesized materials. Both the nanocomposites were characterized by Powder X‐ray diffraction (PXRD), Scanning electron microscopy (SEM), Energy‐dispersive X‐ray analysis (EDAX), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller (BET) analysis. Two distinct morphological as well as surface features have been obtained using 1 and 2 viz. variable spheres (NC‐1) with low surface area and flakes (NC‐2) with high surface area. The adsorption behavior of these nanocomposites on industrial dyes and metals showed excellent dye adsorption (99.6% to 97.2%) and good to moderate metal adsorption efficiency of NC‐1. The NC‐1 could be recycled up to five times for dyes and three times for metals, advocating its practical applications in industry.

Synthesis and Characterization of Cadmium Chalcogenide Nanomaterial (CdE; E=Se/Te) from Novel Single Source Molecular Precursor

Background: Metal chalcogenide nanomaterials represent an important group of efficient materials, in which the subtle variations in shape, size and phase of nano-powders resulted in physical properties (e.g., electronic and optical) differing from their bulk counterparts, which makes them useful materials for various technological devices. Objective: Synthesis and growth of chalcogenide nano powders from novel single source molecular precursors (i.e., Cd(II) bis-(aminopropane) selenide, Cd(II) bis-(aminoethane) telluride) for the production of cadmium chalcogenide (CdE, E= Se/Te) at nano scale. Method: Single source molecular precursor inserted in quinoline, acting as a coordinating solvent at suitable temperature, yielded vacuum dried powders of CdSe and CdTe nanomaterials. Results: The average particle size was estimated as CdSe ≈ 3 nm, and CdTe ≈ 29 nm from powder X-ray diffraction pattern of synthesized nanoparticles. The produced nanomaterials possess optical properties and calculated energy band gap of nanoparticles as CdTe = 5.2 eV and CdSe = 4.0 eV from UV-Visible spectra. Conclusion: The economical, harmless single source molecular method may be a striking technique to fabricate metal chalcogenide nanoparticles.

Cadmium tris(dithiocarbamate) ionic liquids as single source, solvent-free cadmium sulfide precursors.

The first cadmium-based ionic liquids (ILs) have been developed, along with a family of cadmium dialkyldithiocarbamate salts, (cation)[Cd(R2dtc)3], in the pursuit of single source molecular precursors that thermolyse to form cadmium sulfide. Pyrrolidinium cadmium dialkyldithiocarbamate salts, (C4C1py)[Cd(R2dtc)3], salts were established to be ILs through thorough thermal and structural investigation.

Binder Free Modification of Glassy Carbon Electrode by Employing Reduced Graphene Oxide/ZnO Composite for Voltammetric Determination of Certain Nitroaromatics

AbstractReduced Graphene oxide/ZnO nanoflowers (rGO/ZnO‐NFs) composite has been synthesized in‐situ using asymmetric Zn complex (1) as a single‐source molecular precursor (SSMP) with GO at 150 °C. The rGO/ZnO‐NFs composite was characterized by PXRD, UV‐vis, SEM, EDX mapping, TEM and SAED pattern to confirm its purity and morphology. The rGO/ZnO‐NFs composite shows uniform distribution of nanoflowers on graphene sheets. The modified glassy carbon electrode (GCE) was fabricated by drop wise layering of the rGO/ZnO‐NFs composite at the surface of the GCE without using binder. The binder free modified electrode (GCE‐rGO/ZnO) was explored for detection of nitroaromatics such as p‐nitro‐phenol (p‐NP), 2,4‐dinitrophenol (2,4‐DNP), 2,4‐dinitrotoluene (2,4‐DNT) and 2,4,6‐trinitrophenol (2,4,6‐TNP). The fabricated sensor showed remarkable response for the both toxicants and explosives. The LOD, sensitivity and linear range for the studied toxicants and explosives were found to be in a good range: p‐NP=0.93 μM, 240 μA mM−1 cm−2 and 0.2–0.9 mM; 2,4‐DNP=6.2 μM, 203 μA mM−1 cm−2 and 0.1–0.9 mM; 2,4‐DNT=10 μM, 371 μA mM−1 cm−2 and 0.2–0.9 mM; 2,4,6‐TNP=16 μM, 514 μA mM−1 cm−2 and 0.2–0.9 mM, respectively.

Synthesis and characterization of PbS nanoparticles in an ionic liquid using single and dual source precursors

We report a green route for the synthesis of PbS nanoparticles in an imidazolium based ionic liquid (IL) (1-ethyl-3-methylimidazolium methanesulfonate) using single source and dual source precursor methods. Lead ethyl xanthogenate complex was used as single source molecular precursor for the synthesis of PbS nanoparticles, whereas in dual source approach organic sulfur (1-dodecanethiol) and inorganic sulfur (sodium sulfide) sources were used to observe the suitability of different sulfur sources on formation of PbS nanoparticles. The results showed that the temperature has an effect on the as prepared nanoparticles for both routes. X-ray diffraction (XRD) studies confirmed formation of cubic phase of PbS from both routes. Electron microscopy techniques showed that the nanoparticle morphologies differed significantly depending on the synthetic factors such as temperature, nature of precursors and ranged from spherical to cubic shapes.

Facile Access to Amides from Oxygenated or Unsaturated Organic Compounds by Metal Oxide Nanocatalysts Derived from Single-Source Molecular Precursors.

Oxidative amidation is a valuable process for the transformation of oxygenated organic compounds to valuable amides. However, the reaction is severely limited by the use of an expensive catalyst and limited substrate scope. To circumvent these limitations, designing a transition-metal-based nanocatalyst via more straightforward and economical methodology with superior catalytic performances with broad substrate scope is desirable. To resolve the aforementioned issues, we report a facile method for the synthesis of nanocatalysts NiO and CuO by the sol-gel-assisted thermal decomposition of complexes [Ni(hep-H)(H2O)4]SO4 (SSMP-1) and [Cu(μ-hep)(BA)]2 (SSMP-2) [hep-H = 2-(2-hydroxylethyl)pyridine; BA = benzoic acid] as single-source molecular precursors (SSMPs) for the oxidative amidation of benzyl alcohol, benzaldehyde, and BA by using N,N-dimethylformamide (DMF) as the solvent and as an amine source, in the presence of tert-butylhydroperoxide (TBHP) as the oxidant, at T = 80 °C. In addition to nanocatalysts NiO and CuO, our previously reported Co/CoO nanocatalyst (CoNC), derived from the complex [CoII(hep-H)(H2O)4]SO4 (A) as an SSMP, was also explored for the aforementioned reaction. Also, we have carefully investigated the difference in the catalytic performance of Co-, Ni-, and Cu-based nanoparticles synthesized from the SSMP for the conversion of various oxygenated and unsaturated organic compounds to their respective amides. Among all, CuO showed an optimum catalytic performance for the oxidative amidation of various oxygenated and unsaturated organic compounds with a broad reaction scope. Finally, CuO can be recovered unaltered and reused for several (six times) recycles without any loss in catalytic activity.

Germanium Xanthates: Versatile Precursors for Photo Responsive Germanium Sulfide Nanostructures

A convenient synthesis of amorphous and crystalline germanium sulfide nanoparticles and nanosheets by thermolysis of germanium xanthates, [Ge(S2COR′)4] (R′=Et or Pri) and [Bun2Ge(S2COPri)2] as single source molecular precursors, has been reported. The solid state diffuse reflectance spectra showed reasonable blue shifts in the direct band gap (1.75-2.24 eV) of nanostructures relative to its bulk counterpart (1.54-1.65 eV) indicating quantum confinement of GeS nanoparticles. Current-Voltage (I−V) characteristics and photo response properties of the nanosheets and nanoparticles have been evaluated. The tuning of band gap and morphology from sphere to sheet has been demonstrated by varying the reaction duration.

Aerosol assisted chemical vapor deposition of magnesium orthotitanate (Mg2TiO4) films from a trinuclear molecular precursor

Present work demonstrates the synthesis of a novel heterobimetallic complex [Mg2TiO(TFA)6(THF)2(H2O)] (1) (where TFA=trifluoroacetato and THF=tetrahydrofuran), formed from the chemical interaction of magnesium (II) acetate tetrahydrate with titanium (IV) isopropoxide and trifluoroacetic acid in THF solution. Complex (1) adequately characterized through attenuated total reflection infrared spectroscopy, single-crystal X-ray diffraction and thermogravimetric analysis was implemented as single source molecular precursor in the aerosol assisted chemical vapor deposition. The deposition of magnesium orthotitanate (Mg2TiO4) ceramic films on fluorine doped tin oxide coated conducting glass substrate was observed at various temperatures of 500, 550 and 600°C. Film characterization techniques including; X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy divulge the fabrication of phase pure spherical shaped Mg2TiO4 architectures with precise stoichiometry and high purity.

Synthesis, spectroscopic, structural and optical studies of Ru2S3 nanoparticles prepared from single-source molecular precursors

Homonuclear tris-dithiocarbamato ruthenium(III) complexes, [Ru(S2CNR2)3] were prepared and characterized by spectroscopic techniques and thermogravimetric analyses. The thermogravimetric analyses (TGA) of the ruthenium complexes showed that the complexes decompose to ruthenium(III) sulfide nanoparticles. The ruthenium(III) complexes were dispersed in oleic acid and thermolysed in hexadecylamine to prepared oleic acid/hexadecylamine capped Ru2S3 nanoparticles. FTIR revealed that Ru2S3 nanoparticles are capped through the interaction of the –NH2 group of hexadecylamine HDA adsorbed on the surfaces of nanoparticles and it also showed that oleic acid (OA) is acting as both coordinating stabilizing surfactant and capping agent. EDS spectra revealed that the prepared nanoparticles are mainly composed of Ru and S, confirming the formation of Ru2S3 nanoparticles. Powder XRD confirms that the nanoparticles are in cubic phase. The inner morphology of nanoparticles obtained from transmission electron microscopy (TEM) showed nanoparticles with narrow particle size distributions characterized by an average diameter of 8.45 nm with a standard deviation of 1.6 nm. The optical band gap (Eg) determined from Tauc plot are in the range 3.44–4.18 eV.

Effect of the Cation Distribution and Microstructure on the Magnetic Behavior of the CoMn2O4 Oxide.

The sizes of CoMn2O4 nanoparticles can easily be tuned, from 40 to 8 nm, depending on the temperature of decomposition of the single-source molecular precursor {[Co(bpy)3][Mn2(C2O4)3]·H2O}n. The structural features of the CoMn2O4 spinel are also affected by the heat treatment temperature, showing a pronounced expansion of unit cell parameters as a consequence of thermally induced cation redistribution between tetrahedral and octahedral sites. Moreover, the magnetic behavior of CoMn2O4 was successfully tailored as well; depending on the heat treatment, it is possible to switch between the superparamagnetic and ferrimagnetic ordering and to tailor the magnetic transition temperatures, i.e., the boundaries between the hard and soft magnetic behavior.

Synthesis and characterization of CdS nanocrystallites and OMWCNT-supported cadmium sulfide composite and their photocatalytic activity under visible light irradiation

CdS nanocrystallites and CdS- oxidized multiwalled carbon nanotubes (OMWCNT) composite were prepared by the solvothermal decomposition of a single-source molecular precursor, [Cd(pip.dtc)2] (pip.dtc = piperidine dithiocarbamate) in the presence of ethylene glycol. The as prepared CdS nanocrystallites and CdS-OMWCNT composite were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-vis and Raman spectroscopy. Peak broadening in the XRD shows the formation of nanocrystalline CdS. TEM images of CdS nanocrystallites revealed the nearly spherical shape morphology of the particles, whereas, TEM images of composite showed the deposition of CdS nanocrystallites on the OMWCNT. EDX measurements matches with a 1:1 stoichiometry of Cd and S in CdS nanocrystallites, whereas, that of the composite showed the presence of Cd and S along with C. The vibrational properties of CdS nanocrystallites and their composite with OMWCNT were studied by Raman spectroscopy. Furthermore, the photocatalytic activity studies for the degradation of methylene blue under visible light irradiation using these materials were carried out. The surface area calculated using BET surface analyzer for CdS-OMWCNT composite (148.31 m2/g) was found to be more compared to bare CdS nanocrystallites (56.78 m2/g). The CdS-OMWCNT composite exhibited very good photocatalytic activity for the degradation of methylene blue under visible light irradiation which has been attributed to the increased surface area and synergistic effect in the composite compared to bare CdS nanocrystallites.

Studies regarding ZnS:Mn nanopowders prepared from single source molecular precursor using microwave-assisted decomposition

Nanocrystalline undoped and manganese doped zinc sulphide (ZnS) powders were prepared by microwave—assisted solvothermal decomposition of zinc-manganese diethyldithiocarbamate as single-source molecular precursor. The precursors are being obtained in aqueous solution, from sodium diethyldithiocarbamate and zinc-manganese acetate mixtures containing variable amounts of manganese. Complementary investigations such as: thermal analysis, X-ray diffraction, SEM and BET were used to characterize both the precursors and phosphors. After the solvothermal treatment, the specific surface area of the powders increases from 2.04m2/g to 154.5m2/g. Phosphor samples consist of small particles (∼12nm) which present a high tendency to form spherical agglomerations. Photoluminescence spectra show a dominant yellow emission peak at 568nm accompanied by several weaker peaks. In this paper, we discuss about the manganese incorporation effect in ZnS lattice concerning the morpho-structural and luminescent characteristics of the samples.

Synthesis and Characterization of a Novel Borazine-Type UV Photo-Induced Polymerization of Ceramic Precursors.

A preceramic polymer of B,B′,B′′-(dimethyl)ethyl-acrylate-silyloxyethyl-borazine was synthesized by three steps from a molecular single-source precursor and characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectrometry. Six-member borazine rings and acrylate groups were effectively introduced into the preceramic polymer to activate UV photo-induced polymerization. Photo-Differential Scanning Calorimetry (Photo-DSC) and real-time FTIR techniques were adapted to investigate the photo-polymerization process. The results revealed that the borazine derivative exhibited dramatic activity by UV polymerization, the double-bond conversion of which reached a maximum in 40 s. Furthermore, the properties of the pyrogenetic products were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), which proved the ceramic annealed at 1100 °C retained the amorphous phase.

Efficient Pt-free electrocatalyst for oxygen reduction reaction: Highly ordered mesoporous N and S co-doped carbon with saccharin as single-source molecular precursor

Despite that nitrogen (N) and sulfur (S) co-doped ordered mesoporous carbon (OMC) as Pt-free catalyst for oxygen reduction reaction (ORR) shows a desirable performance, the synthesis method is always complicated and expensive, which greatly hinders its development and application. In the present work, a highly ordered mesoporous N and S co-doped carbon material is developed. The material is obtained by combining hard template and high-temperature pyrolysis method using cheap saccharin as a single-source molecular precursor, SBA-15 as the hard template and FeCl3 as the catalyst to promote the carbonization process. It is found that the as-prepared SN-OMC catalyst, compared with the commonly used commercial Pt/C (20wt.%), exhibits comparable ORR electrocatalytic activity with mainly four-electron (4e−) process, superior stability and inertness to methanol in alkaline media, which could mainly benefit from the highly ordered mesoporous structure and the synergistic effect caused by the dual N and S doping. These advantages render SN-OMC a promising ORR electrocatalyst and a cheap alternative to Pt/C for practical fuel cell applications.

Super paramagnetic iron oxide and gadolinium (FeGdO3) nanopowder synthesized by hydrolytic approach passes high level of biocompatibility and MRI-based dual contrast property for competent molecular imaging and therapeutic interventions

The synthesis of monodispersable FeGdO3 nanopowder with well-defined architectural framework was carried out by using metal chloride as a single source molecular precursor by modifying reaction conditions to obtain an ultra-pure surface area for better understanding the chemistry involved in micro to nanoscale. By controlling the reaction parameters at the molecular level helps to synthesize a technology oriented nanomaterials with high crystalline particle size and shape with required surface morphologies at the nanoscale. The FeGdO3 nanomaterial was characterized by XRD, SEM, TEM, thermal analysis and FT-IR. The x-ray diffraction patterns indicate the formation of square planar crystallite size of 41.65 nm after annealing. The integral properties of nanomaterial depend upon the synthetic approach through self-assembly which helps in the formation of primary nuclei from metal chloride as smart molecular precursor. This opens a new exciting vista for a better understanding of the reaction conditions and growth mechanisms. We used two cell types; human mesenchymal stem cells (MSCs) derived from umbilical cord blood and human neuronal cells to evaluate the toxicity and dual contrast properties of FeGdO3 nanoparticles further their application in high contrast imaging and stem cell labeling and tracking. We found that various concentrations of FeGdO3 nanoparticles do not influence the cellular mechanisms involved in cell survival and proliferation which proves high biocompatibility nature of FeGdO3 nanoparticles with cells. Enhanced signal intensity during low-field MRI (1.5T) with iron oxide and gadolinium provides its further clinical implications as dual contrast imaging agent with more advancements.

Electrically conducting palladium selenide (Pd4Se, Pd17Se15, Pd7Se4) phases: synthesis and activity towards hydrogen evolution reaction

Electrically conducting, continuous films of different phases of palladium selenides are synthesized by the thermolysis of single source molecular precursors. The films are found to be adherent on flat substrates such as glass, indium tin oxide and glassy carbon and are stable under electrochemical conditions. They are electrocatalytically active and in particular, for hydrogen evolution reaction. Catalytic activities with low Tafel slopes of 50-60 mV per decade are observed.

Ga[OSi(O(t)Bu)3]3·THF, a thermolytic molecular precursor for high surface area gallium-containing silica materials of controlled dispersion and stoichiometry.

The molecular precursor tris[(tri-tert-butoxy)siloxy]gallium, as the tetrahydrofuran adduct Ga[OSi(O(t)Bu)3]3·THF (), was synthesized via the salt metathesis reaction of gallium trichloride with NaOSi(O(t)Bu)3. This complex serves as a model for isolated gallium in a silica framework. Complex decomposes thermally in hydrocarbon solvent, eliminating isobutylene, water, and tert-butanol to generate high surface area gallium-containing silica at low temperatures. When thermal decomposition was performed in the presence of P-123 Pluronic as a templating agent the generated material displayed uniform vermicular pores. Textural mesoporosity was evident in untemplated material. Co-thermolysis of with HOSi(O(t)Bu)3 in the presence of P-123 Pluronic led to materials with Ga : Si ratios ranging from 1 : 3 to 1 : 50, denoted UCB1-GaSi3, UCB1-GaSi10, UCB1-GaSi20 and UCB1-GaSi50. After calcination at 500 °C these materials exhibited decreasing surface areas and broadening pore distributions with increasing silicon content, indicating a loss of template effects. The position and dispersion of the gallium in UCB1-GaSi materials was investigated using (71)Ga MAS-NMR, powder XRD, and STEM/EDS elemental mapping. The results indicate a high degree of gallium dispersion in all samples, with gallium oxide clusters or oligomers present at higher gallium content.

Understanding the temperature-dependent evolution of solution processed metal oxide transistor characteristics based on molecular precursor derived amorphous indium zinc oxide

Photoelectron emission spectroscopy and positron annihilation spectroscopy allow a comprehensive interpretation of the performance of IZO-based TFTs.

A Facile Molecular Precursor Route to Metal Phosphide Nanoparticles and Their Evaluation as Hydrodeoxygenation Catalysts

Metal phosphides have been identified as a promising class of materials for the catalytic upgrading of bio-oils, which are renewable and potentially inexpensive sources for liquid fuels. Herein, we report the facile synthesis of a series of solid, phase-pure metal phosphide nanoparticles (NPs) (Ni2P, Rh2P, and Pd3P) utilizing commercially available, air-stable metal–phosphine complexes in a one-pot reaction. This single-source molecular precursor route provides an alternative method to access metal phosphide NPs with controlled phases and without the formation of metal NP intermediates that can lead to hollow particles. The formation of the Ni2P NPs was shown to proceed through an amorphous Ni–P intermediate, leading to the desired NP morphology and metal-rich phase. This low-temperature, rapid route to well-defined metal NPs is expected to have broad applicability to a variety of readily available or easily synthesized metal–phosphine complexes with high decomposition temperatures. Hydrodeoxygenation of ...