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An oxalate complex of vanadyl(IV) (Bu4N)2[VO(C2O4)2] (I) was synthesized and used as a vanadium precursor. The synthesis and characterization of the double complex salts [Pt(NH3)4][VO(H2O)(C2O4)2]·2H2O (III) and {[Pt(NH3)4][VO(C2O4)2]}n (IV) were carried out. The complexes obtained were characterized by IR and diffuse reflectance spectroscopy, single-crystal and powder X-ray diffraction, and EPR. The magnetic properties of I, III, and IV were also studied. The process of thermal decomposition of the synthesized complexes in reducing and inert atmospheres was studied, and the composition of the released gases was determined. Thermal decomposition of the salts in a hydrogen atmosphere at 600 °C resulted in the formation of a bimetallic solid solution, Pt0.6V0.4. [ABSTRACT FROM AUTHOR]

A new approach based on a combination of synchrotron radiation techniques, such as X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES), and powder X-ray diffraction (PXRD), has been applied to in situ study the processes of thermal decomposition of inorganic compounds and the formation of bimetallic nanoalloys. As an example, a double complex salt, [Pd(NH3)4][PtCl6], was selected because of (i) its sufficiently complicated structure and previous studies conducted via thermal analysis, ex situ PXRD and XPS, and (ii) its use as a prospective single-source precursor for the preparation of bimetallic (PdPt) nanoparticles or nanoalloys. The differences between the mechanisms based on ex situ and in situ data have been discussed for the first time. It has been found that the first step of thermal decomposition is related to the formation of crystalline [Pd(NH3)2Cl2][Pt(NH3)2Cl4]. Further decomposition results in the formation of {PdCl2}, {PtCl2}, and (NH4)2[PtCl6] in the second step. In the final step, the intermediates are completely reduced, and a bimetallic nanoalloy is formed. The different means of Pd and Pt reduction on the surface and in the bulk result in the formation of a disordered nanoalloy with possible monometallic inclusions. Further heating orders the nanoalloy that is accompanied by a decrease in the positive charge on Pt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Pd (5%) single-phase alloy was used as a catalyst for CCVD of C 2 H 4 Cl 2. • Joint catalytic processing of C 2 H 4 Cl 2 and CH 3 CN into N-doped CNF was studied. • By XPS, produced N-CNF material contains 1.4–2.2 wt.% of structural nitrogen. • Obtained N-doped carbon filaments have regular segmental structure. • The produced N-doped CNF is characterized by S BET ∼ 390−450 m2/g, V pore ∼ 0.6 cm3/g. A single-phase micro-disperse Ni-Pd (5 wt.%) alloy prepared by coprecipitation technique was studied as a catalyst precursor for the synthesis of the nanostructured carbon product. Catalytic synthesis of N-doped carbon nanofibers was implemented by the joint decomposition of C 2 H 4 Cl 2 and CH 3 CN vapors in H 2 excess at 600 °C. The in situ kinetic experiments performed in a flow gravimetric setup with McBain balances showed that the carbon deposition process is characterized by an induction period (18−20 min). The intensive metal dusting of the Ni-Pd alloyed precursor in reaction conditions was found to lead to its complete disintegration. The obtained submicron-sized Ni-Pd particles were shown by XRD to have the same composition as the starting Ni-Pd (5%) precursor. The growth of carbon filaments accompanied the rapid disintegration of Ni-Pd alloy. The addition of acetonitrile vapors into the reaction mixture was found to enhance carbon yield from 24 (0%) to 40.5 (5 vol.%) and 50.9 (8 vol.%) grams per 1 g of catalyst for 2 h of reaction. Joint catalytic processing of C 2 H 4 Cl 2 and CH 3 CN was shown to be sufficient for the production of carbon nanofibers doped with nitrogen. According to XPS and EDX data, the average amount of nitrogen within the obtained N-CNF was about 1.8 wt.%. It was revealed by microscopic studies (SEM, TEM) that the produced N-doped carbon filaments are characterized with a rather regular segmental structure similar to that observed for a reference sample of N-free CNF. The synthesized N-CNF samples are characterized by I D /I G ∼ 1.3 (Raman spectroscopy) and high textural parameters (S BET ∼ 390−450 m2/g, V pore ∼ 0.6 cm3/g). [ABSTRACT FROM AUTHOR]

A new approach based on a combination of synchrotron radiation techniques, such as X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES), and powder X-ray diffraction (PXRD), has been applied to in situ study the processes of thermal decomposition of inorganic compounds and the formation of bimetallic nanoalloys. As an example, a double complex salt, [Pd(NH3)4][PtCl6], was selected because of (i) its sufficiently complicated structure and previous studies conducted via thermal analysis, ex situ PXRD and XPS, and (ii) its use as a prospective single-source precursor for the preparation of bimetallic (PdPt) nanoparticles or nanoalloys. The differences between the mechanisms based on ex situ and in situ data have been discussed for the first time. It has been found that the first step of thermal decomposition is related to the formation of crystalline [Pd(NH3)2Cl2][Pt(NH3)2Cl4]. Further decomposition results in the formation of {PdCl2}, {PtCl2}, and (NH4)2[PtCl6] in the second step. In the final step, the intermediates are completely reduced, and a bimetallic nanoalloy is formed. The different means of Pd and Pt reduction on the surface and in the bulk result in the formation of a disordered nanoalloy with possible monometallic inclusions. Further heating orders the nanoalloy that is accompanied by a decrease in the positive charge on Pt. [ABSTRACT FROM AUTHOR]

Highlights: [•] [Pd(NH3)4]MoO4 as a precursor for Pd–Mo-containing catalysts. [•] Different products are formed depending on atmosphere of thermal decomposition. [•] Thermolysis in He atmosphere affords finely mixed two-phase nanosized system Pd–MoO2. [•] Pd–MoO2 system can be a promising catalyst both in pure and supported form. [Copyright &y& Elsevier]

Abstract: A series of 1.8wt.% PdAu/γ-Al2O3 catalysts with a mean metal particle size of more than 10nm and different Pd/Au ratios were prepared by impregnation followed by hydrazine reduction and tested in the decomposition of vapour phase formic acid (2.2vol.%, 1bar) with and without added CO to the gas mixture. The catalytic activity was correlated with the bulk (AAS, XRD, EDS/TEM) and surface (XPS) composition of PdAu particles. A novel result was obtained that the surface composition of the particles did not change despite a considerable variation of the Au atomic fraction and it was found to be close to that of the Pd2Au alloy. The activity of the Au/Al2O3 catalyst was negligible compared with that of the Pd/Al2O3 catalyst being a factor of 65 lower per gram of metal at 403K. The surface electronic properties (XPS) and the catalytic activity of the Pd2Au layer calculated per one surface Pd atom (TOF) did not depend on the bulk composition of the metal particles. A lower activity of the Pd2Au layer as compared with the pure Pd layer (2–3 times) was observed, but the activation energies for the Pd and PdAu catalysts were similar (40kJmol−1) and were lower than that for the Au/Al2O3 catalyst (62kJmol−1). Addition of CO led to a considerable inhibition of the reaction for all PdAu catalysts, this being accompanied by an increase in the activation energy to 69kJmol−1. [Copyright &y& Elsevier]

Abstract: Permanganate salt of the complex cation trans-[Rh(γ-Pic)4Cl2]+ (γ-Pic=γ-picoline) was synthesized. The unusual decomposition reaction of the salt was studied at room temperature. This process has been found to conserve the γ-picoline ligands in cation untouched. A number of transformations in anionic part of salt have been observed. Metallic products of the salt thermal decomposition have been studied. [Copyright &y& Elsevier]

The hydrolysis of [RhCl 6 ] 3- in NaOH-water solutions was studied by spectrophotometric methods. The reaction proceeds via successive substitution of chloride with hydroxide to quantitatively form [Rh(OH) 6 ] 3- . Ligand substitution kinetics was studied in an aqueous 0.434-1.085 M NaOH matrix in the temperature range 5.5-15.3 °C. Transformation of [RhCl 6 ] 3- into [RhCl 5 (OH)] 3- was found to be the rate-determining step with activation parameters of ΔH † = 105 ± 4 kJ mol -1 and ΔS † = 59 ± 10 J K -1 mol -1 . The coordinated hydroxo ligand(s) induces rapid ligand substitution to form [Rh(OH) 6 ] 3- . By simulating ligand substitution as a dissociative mechanism, using density functional theory (DFT), we can now explain the relatively fast and slow kinetics of chloride substitution in basic and acidic matrices, respectively. Moreover, the DFT calculated activation energies corroborated experimental data that the kinetic stereochemical sequence of [RhCl 6 ] 3- hydrolysis in an acidic solution proceeds as [RhCl 6 ] 3- → [RhCl 5 (H 2 O)] 2- → cis-[RhCl 4 (H 2 O) 2 ] - . However, DFT calculations predict in a basic solution the trans route of substitution [RhCl 6 ] 3- → [RhCl 5 (OH)] 3- → trans-[RhCl 4 (OH) 2 ] 3- is kinetically favored.