Sn Cations Research Articles

Sn0.24WO3 hexagonal tungsten bronze prepared via the metal chloride route

We report the synthesis of Sn0.24WO3 single crystals via an alternative, less well-known, solid-state synthetic approach that involves the use of tin chloride as a starting material. The compound adopts an unusual variant of the hexagonal tungsten bronze structure in space group P6/mmm (a ​= ​7.4264(7) Å and c ​= ​3.7843(4) Å) with a previously unreported distribution of Sn cations, disordered over two distinct sites in the tunnels. Sn0.24WO3 shows no signs of superconductivity down to 170 ​mK and exhibits weakly-metallic conducting behavior.

Sn 5s2 lone pairs and the electronic structure of tin sulphides: A photoreflectance, high-energy photoemission, and theoretical investigation

The effects of Sn $5s$ lone pairs in the different phases of Sn sulphides are investigated with photoreflectance, hard x-ray photoemission spectroscopy (HAXPES), and density functional theory. Due to the photon energy-dependence of the photoionization cross sections, at high photon energy, the Sn $5s$ orbital photoemission has increased intensity relative to that from other orbitals. This enables the Sn $5s$ state contribution at the top of the valence band in the different Sn-sulphides, SnS, ${\mathrm{Sn}}_{2}{\mathrm{S}}_{3}$, and ${\mathrm{SnS}}_{2}$, to be clearly identified. SnS and ${\mathrm{Sn}}_{2}{\mathrm{S}}_{3}$ contain Sn(II) cations and the corresponding Sn $5s$ lone pairs are at the valence band maximum (VBM), leading to $\ensuremath{\sim}1.0$--1.3 eV band gaps and relatively high VBM on an absolute energy scale. In contrast, ${\mathrm{SnS}}_{2}$ only contains Sn(IV) cations, no filled lone pairs, and therefore has a $\ensuremath{\sim}2.3$ eV room-temperature band gap and much lower VBM compared with SnS and ${\mathrm{Sn}}_{2}{\mathrm{S}}_{3}$. The direct band gaps of these materials at 20 K are found using photoreflectance to be 1.36, 1.08, and 2.47 eV for SnS, ${\mathrm{Sn}}_{2}{\mathrm{S}}_{3}$, and ${\mathrm{SnS}}_{2}$, respectively, which further highlights the effect of having the lone-pair states at the VBM. As well as elucidating the role of the Sn $5s$ lone pairs in determining the band gaps and band alignments of the family of Sn-sulphide compounds, this also highlights how HAXPES is an ideal method for probing the lone-pair contribution to the density of states of the emerging class of materials with $\mathrm{n}{s}^{2}$ configuration.

Thermally stable energy storage properties in relaxor BNT‐6BT‐modified antiferroelectric PNZST ceramics

AbstractRelaxor ferroelectric 0.94Na0.5Bi0.5TiO3‐0.06BaTiO3‐modified antiferroelectric Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 ceramics, (1−x)PNZST‐x(BNT‐6BT), were prepared to acquire high energy storage and thermal stability properties. X‐ray diffraction and element mapping revealed that a solid solution between PNZST and BNT‐6BT occurs, and Ti cations enter the PNZST lattice, partly extruding Sn cations and leading to the formation of isolated SnO2 particles at the grain boundaries and a 0‐3 type composite structure. Such a composite structure helps to create deviatoric stress in the solid solution component. The BNT‐6BT content significantly influences the energy storage capacity, and the x = 0.2 composition renders optimal performance. The room‐temperature‐recoverable energy density and energy efficiency are 2.23 J/cm3 and 78%, respectively, at 260 kV/cm. Both parameters vary less than 6% within a temperature range of 25°C and 125°C. The improved energy storage and temperature stability indicate that the ceramics can potentially be applied in pulse power capacitors and that this relaxor‐modified antiferroelectric ceramic preparation method is a valuable reference for further optimizing the functional properties.

Synthesis of CuNiSn LDHs as highly efficient Fenton catalysts for degradation of phenol

A series of CuNiSn ternary layered double hydroxides (LDH) were synthesized as catalysts for degradation of phenol via Fenton reaction. At Cu/Ni ratios above 0.2, copper chloride hydroxide co-exists with LDH. Multivalent Cu+/Cu2+, Ni2+/Ni3+ and Sn2+/Sn4+ ions are present in LDH due to the electron transfer between metals in brucite-like sheets. The catalytic activity varies directly with the Cu+ percentage, and the maximum activity is achieved at Cu/Ni/Sn ratio of 1/2/0.75. This catalyst (Cu1Ni2Sn0.75) can mineralize 97.8% phenol under mild conditions and shows good stability. Multivalent Cu, Ni and Sn cations in LDH could construct a closed electron cycle. This allows the rapid regeneration of Cu+ active species through electron transfer within LDH rather than through slow Fenton-like reaction, as what usually happens in conventional Fenton catalysts. In addition, a positive synergistic effect between copper chloride hydroxide and LDH is observed in Cu1Ni2Sn0.75, favoring the formation of Cu+.

Experimental design on determination of Sn(II) by the modified carbon paste electrode with Fe(II)-exchanged clinoptilolite nanoparticles

In the present study, clinoptilolite nanoparticles (CN) were prepared in a planetary ball-mill instrument and ion exchanged in Fe(II) solution. The resulted Fe(II)–CN material was then used as an effective modifier to modify carbon paste electrode (CPE). When the resulted Fe(II)–CN-CPE electrode was immersed in HCl supporting electrolyte, Fe(II) cations were located at the electrode-solution interface via an ion exchange process with protons which were present in the supporting electrolyte solution. Next, Fe(II) cations could be immediately oxidized to Fe(III) at the electrode surface by scanning the potential toward more positive values in order to create an anodic peak current. When Sn(II) cations were added into the supporting electrolyte solution, they could immediately react with the produced Fe(III) cations as well. This reaction provided more Fe(II) cations at the electrode-solution interface, causing a significant increase in the peak current of the electro-oxidation of Fe(II) cations. Hence, this electrocatalytic current was utilized for the voltammetric determination of Sn(II) in aqueous solution. In addition, the experimental design by response surface methodology was applied to study the interaction effects between the influencing variables. Further, the best voltammetric response was obtained by performing the voltammetric measurement based on the run (with conditions of pH 2, ν = 100 mV s−1, modifier% = 10%, and CFe = 0.7 mol L−1). Finally, the Fe(II)–CN-CPE electrode showed a linear response in the concentration range of 10–400 μmol L−1 Sn(II) with a detection limit (DL) of 0.1 μmol L−1.

(Cu)tet(Cr2-xSnx)octS4-ySey Spinels: Crystal Structure, Density Functional Theory Calculations, and Magnetic Behavior.

A new series of (Cu)tet[Cr2-xSnx]octS4-ySey compounds was prepared by solid-state reaction at high temperature. Determination of the crystal structures by single-crystal X-ray diffraction revealed that CuCr1.0Sn1.0S2.1Se1.9, CuCr1.2Sn0.8S2.1Se1.9, CuCr1.3Sn0.7S2.2Se1.8, and CuCr1.5Sn0.5S2.2Se1.8 crystallize in a normal spinel-type structure (cubic Fd3m space group). The powder X-ray diffraction patterns and Rietveld refinements of nominal CuCr2-xSnxS2Se2 (x = 0.2, 0.4, 0.6, 0.8, and 1.0) were consistent with single-crystal X-ray diffraction data. Raman scattering analysis revealed that the A1g, Eg, and three F2g vibrational modes were observed in the spectra. The signal at ∼382 cm-1, corresponding to the A1g mode, is attributed to symmetrical stretching of the chalcogen bond with respect to the tetrahedral metal. The samples with x = 0.2 and 0.4 exhibited ferromagnetic behavior, characterized by large positive θ values of +261 and +189 K, respectively. In contrast, antiferromagnetic (AF) behavior was observed for CuCrSnS2Se2 with a Néel temperature (TN) of 18.8 K and a θ value of -36.0 K. Density functional theory (DFT) and effective magnetic moments (μeff/μtheo) experimentally measured showed that the Sn ion is in oxidation state of 4+, i.e., diamagnetic behavior. DFT calculations revealed that the most stable magnetic state of CuCr1.0Sn1.0S2Se2 was AF with exchange constants for first- and second-neighbor interactions of J1 = 56.22 cm-1 and J2 = -33.88 cm-1. Thus, the AF interactions between ferromagnetic chains in CuCr1.0Sn1.0S2Se2 originate from the presence of diamagnetic Sn cations.

Electrocatalytic Determination of Hg(II) by the Modified Carbon Paste Electrode with Sn(IV)-Clinoptilolite Nanoparticles

In this work, the electro-reduction of Hg(II) was studied by the modified carbon paste electrode (CPE) with clinoptilolite nanoparticles (CNP) ion exchanged with Sn(IV) cations (Sn(IV)-CNP/CPE). When the Sn(IV)-CNP/CPE electrode was immersed in HCl as supporting electrolyte, the voltammetric peak currents were observed for Sn(IV)/Sn(II) redox reactions in cyclic voltammetry. The reduction peak current of Sn(IV) was increased in the presence of Hg(II) cations in solution. This increase in the peak current was used for the voltammetric determination of Hg(II) in solution. The constructed calibration curve in square wave voltammetry showed a proportional relationship between the peak current and concentration of Hg(II) cations in the range of 0.1–100 μM with a detection limit of 0.01 μM. The electrode showed good selectivity towards Hg(II) cations in the hard conditions in the presence of some strong oxidizing agents. The selected cations could strongly compete with Hg(II) cations to oxidize the electrogenerated Sn(II) cations. The electrode had also good applicability in Hg determination in real samples such as tuna fish, sea fish, mushroom and black tea, river water, and a steel company wastewater samples.

SnO2/Al2O3 catalysts for selective reduction of NOx by propylene: On the promotional effects of plasma treatment in air atmosphere

Abstract To elucidate structure-reactivity relationship and promote the reaction performance of SnO2/Al2O3 for NOx-SCR, a series of catalysts have been prepared by impregnation method and treated by non-thermal dielectric barrier discharge (DBD) plasma. It is quantified that SnO2 disperses on γ-Al2O3 with a monolayer capacity of 0.262 mmol 100 m−2. The catalyst with a SnO2 loading close to the capacity displays the best activity, testifying the presence of a monolayer threshold effect. Plasma treating can improve SnO2 dispersion evidently, thus expanding the monolayer capacity to 0.340 mmol 100 m−2. As a result, the surface Sn cations are enriched, which improves the surface acidity of the catalysts, benefits the adsorption and activation of NO and C3H6 molecules, and eventually enhances the activity. It is concluded that the surface acidic site amount determines the reaction activity of catalysts. Over SnO2/Al2O3 catalysts, NOx-SCR by C3H6 follows a Langmuir-Hinshelwood mechanism. Surface monodentate nitrate and formate are found to be the major active intermediates for the reaction.

Role of dilution on the electronic structure and magnetic ordering of spinel cobaltites

By means of the first-principles density functional theory ($\mathrm{DFT}+U$) calculations and experiments, we investigate the role of dilution on the structural, magnetic, electronic, and optical properties of the antiferromagnetic (AFM) spinel ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$ having N\'eel temperature $({T}_{\text{N}})\ensuremath{\sim}30$ K. As the octahedral cobalt site of spinel lattice is diluted with Ge, Al, Ti, Ru, and Sn cations, we observe a substantial increase in the size of the unit cell as well as destruction of the long-range magnetic ordering with a spin-orbit compensation effect. The ferrimagnetic ordering in diluted inverse spinels such as ${\mathrm{Co}}_{2}\mathrm{\ensuremath{\Sigma}}{\mathrm{O}}_{4}$ ($\mathrm{\ensuremath{\Sigma}}$ = Ti and Sn) emerges due to the difference in the magnetic moments of two sublattices A (3.87 ${\ensuremath{\mu}}_{\text{B}}$) and B (4.16 ${\ensuremath{\mu}}_{\text{B}}$ for ${\mathrm{Co}}_{2}{\mathrm{SnO}}_{4}$ and 5.19 ${\ensuremath{\mu}}_{\text{B}}$ for ${\mathrm{Co}}_{2}{\mathrm{TiO}}_{4}$). Experiments and DFT calculations indicate antiferromagnetic configuration for ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$, ${\mathrm{Co}}_{2}{\mathrm{AlO}}_{4}$ (${T}_{\text{N}}\ensuremath{\sim}4.8$ K) spinels with an equal and opposite moment of $\ensuremath{\sim}2.60$ ${\ensuremath{\mu}}_{\text{B}}$ in tetrahedral sites of divalent Co ions and negligible contribution from trivalent B-site Co due to the complete filling of ${t}_{2g}$ levels having a giant crystal field of $\ensuremath{\sim}2.5$ and 1.8 eV, respectively. However, in ${\mathrm{Co}}_{2}{\mathrm{GeO}}_{4}$ (${T}_{\text{N}}\ensuremath{\sim}20.4$ K) case AFM behavior originates due to the opposite spins at octahedral sites of divalent Co ions. The remaining spinels ${\mathrm{Co}}_{2}{\mathrm{TiO}}_{4}$ (${T}_{\text{N}}\ensuremath{\sim}47.8$ K), ${\mathrm{Co}}_{2}{\mathrm{RuO}}_{4}$ (${T}_{\text{N}}\ensuremath{\sim}16$ K), and ${\mathrm{Co}}_{2}{\mathrm{SnO}}_{4}$ (${T}_{\text{N}}\ensuremath{\sim}41$ K) are more favorable to ferrimagnetic structure as evident from our magnetization measurements with a different temperature dependence of magnetic moments A(T) and B(T) at tetrahedral A and octahedral B sites, respectively. The variation in the energy band gap (${E}_{g}=1.68\ensuremath{\rightarrow}3.28$ eV for ${\mathrm{Co}}_{2}{\mathrm{RuO}}_{4}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}{\mathrm{Co}}_{2}{\mathrm{GeO}}_{4}$) obtained from $\mathrm{DFT}+U$ calculations are in good agreement with our experimental results (${E}_{g}=1.52\ensuremath{\rightarrow}3.16$ eV) obtained from the diffusive reflectance spectroscopy. The extent of exchange splitting ${\mathrm{\ensuremath{\Delta}}}_{\text{EX}}^{{e}_{g}}$ of tetrahedral ${\mathrm{Co}}^{2+}$ varies between 1.8 and 1.3 eV for ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$ and ${\mathrm{Co}}_{2}{\mathrm{AlO}}_{4}$, respectively. However, ${\mathrm{\ensuremath{\Delta}}}_{\text{EX}}^{{t}_{2g}}$ exhibits a decreasing trend ($5.2\ensuremath{\rightarrow}3.6$ eV for ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}\ensuremath{\rightarrow}{\mathrm{Co}}_{2}{\mathrm{SnO}}_{4}$) with increasing the lattice parameter, except for cobalt-orthogermanate ${\mathrm{Co}}_{2}{\mathrm{GeO}}_{4}$.

A comprehensive study on the kinetic aspects and experimental design for the voltammetric response of a Sn(IV)-clinoptilolite carbon paste electrode towards Hg(II)

The Sn(IV) ion exchanged clinoptilolite nanoparticles (Sn(IV)-CNP) were used as a modifier for the modification of carbon paste electrode (CPE). When the modified electrode was immersed in HCl supporting electrolyte, Sn(IV) cations can locate at the Sn(IV)-CNP-CPE electrode surface via an ion exchange process with protons of the supporting electrolyte. These electroactive cations underwent a redox process at the electrode surface. Increased peak current of Sn(IV) reduction by adding Hg(II) analyte into the supporting electrolyte solution was used for the voltammetric determination of Hg(II). Focus of the work was on study of the interaction effects between the influencing variables in square wave voltammetric response of the modified electrode in the presence of Hg(II) cations by designing the experiments (via response surface methodology: RSM) and study of some kinetic aspects of the process in linear sweep voltammetry and chronoamperometry. The optimal run in RSM was obtained in: Csn(IV) in ion exchange solution: 0.37 mol L−1, modifier%: 22.45, amplitude: 60 mV and step potential: 2.9 mV. The response current of the modified electrode was proportion to Hg(II) concentration in the range of 0.1–10 μM (DL: 0.05 μM) in square wave voltammetry and in the range of 0.1–10 μM (DL: 0.01 μM) in chronoamperometry. Using the Tafel plots, the values of α and Ko were determined for the modified electrode as 0.298, 1.91 × 10−3 s−1 and 0.311, 6.62 × 10−3 s−1 in the absence and presence of Hg(II) cations, respectively.

Multistep Lithiation of Tin Sulfide: An Investigation Using in Situ Electron Microscopy.

Two-dimensional (2D) metal sulfides have been widely explored as promising electrodes for lithium-ion batteries since their two-dimensional layered structure allows lithium ions to intercalate between layers. For tin disulfide, the lithiation process proceeds via a sequence of three different types of reactions: intercalation, conversion, and alloying, but the full scenario of reaction dynamics remains nebulous. Here, we investigate the dynamical process of the multistep reactions using in situ electron microscopy and discover the formation of an intermediate rock-salt phase with the disordering of Li and Sn cations after initial 2D intercalation. The disordered cations occupy all the octahedral sites and block the channels for intercalation, which alter the reaction pathways during further lithiation. Our first-principles calculations of the nonequilibrium lithiation of SnS2 corroborate the energetic preference of the disordered rock-salt structure over known layered polymorphs. The in situ observations and calculations suggest a two-phase reaction nature for intercalation, disordering, and following conversion reactions. In addition, in situ delithiation observation confirms that the alloying reaction is reversible, while the conversion reaction is not, which is consistent with the ex situ analysis. This work reveals the full lithiation characteristic of SnS2 and sheds light on the understanding of complex multistep reactions in 2D materials.

Ni/Y2B2O7 (B[dbnd]Ti, Sn, Zr and Ce) catalysts for methane steam reforming: On the effects of B site replacement

In this study, a series of Y2B2O7 compounds with a fixed Yttrium cation A site but with different B (BTi, Sn, Zr and Ce) sites have been synthesized and used to support Ni for methane reforming for hydrogen production. By replacing the B site with Ti, Sn, Zr and Ce cations in sequence, the rA/rB ratios of the resulted Y2B2O7 compounds become smaller. As a consequence, the crystalline structures of the compounds become less ordered with the transformation of the bulk phase from well-ordered pyrochlore (Y2Ti2O7) to less ordered pyrochlore (Y2Sn2O7) and subsequently to defective fluorite (Y2Zr2O7 and Y2Ce2O7). XPS results have revealed that on the surfaces of Ni/Y2Ti2O7 and Ni/Y2Ce2O7, higher O/(Y + B) atomic ratios can be achieved than on the other two catalysts, indicating the presence of more abundant oxygen species, which is beneficial to remove the carbon deposits. In comparison with Y2Zr2O7 and Y2Ce2O7, the supported Ni or Ni3Sn2 active sites have stronger interaction with Y2Ti2O7 and Y2Sn2O7 supports, which anchors the active sites tighter on the supports and suppresses its aggregation effectively, thus obtaining catalysts with larger active metallic surface areas and better thermal stability. As a result, the stability and coking resistance of the catalysts can be enhanced. For the reduced Ni/Y2Sn2O7, Ni3Sn2 alloy has formed, which improves the coking resistance of the catalyst but degrades its activity significantly. On Ni/Y2Ti2O7 catalyst, which possesses the largest amount of active surface oxygen species, the strongest Ni interaction with the support can also be obtained, therefore, it exhibits the highest activity, stability and strongest coking resistance among all of the catalysts.

Hydrodeoxygenation of phenol over zirconia supported Pd bimetallic catalysts. The effect of second metal on catalyst performance

This work investigated the effect of the addition of a second metal (Cu, Ag, Zn, Sn) on the performance of Pd/ZrO2 catalyst for HDO of phenol at 573 K in the gas phase. The incorporation of dopants resulted in the formation of Pd–X (Cu, Ag, Zn) alloys, which reduced the reaction rate for HDO and increased the selectivity to hydrogenation products (cyclohexanone and cyclohexanol). For PdSn/ZrO2, alloying was also observed but tin oxide was still present on the surface after reduction at 773 K. For Pd/ZrO2 and PdSn/ZrO2, the oxophilic sites represented by Zr and Sn cations promotes the hydrogenation of the carbonyl group of the keto-tautomer intermediate formed, producing benzene as the main product. All catalysts significantly deactivated during the reaction but the deactivation degree depended on the type of the metal. Pd/ZrO2 and PdZn/ZrO2 and PdAg/ZrO2 exhibited approximately the same deactivation degree. However, the loss of activity was less pronounced for PdSn/ZrO2 catalyst. Pd dispersion significantly decreased during the reaction, indicating that the sintering of Pd particles is one of the causes for catalyst deactivation.

Air and moisture stable covalently-bonded tin(ii) coordination polymers.

Four covalently-bonded tin(ii) coordination polymers, (1)-(4), were hydrothermally prepared in aqueous alkaline media by the reactions of SnSO4 with 1,2,4,5-benzenetetracarboxylic acid (1), 1,3,5-benzenetricarboxylic acid (2), 4-hydroxypyridine-2,6-dicarboxylic acid (3), and 1,3,5-cyclohexanetricarboxylic acid (4). All products were structurally authenticated by single-crystal X-ray diffraction, and the number of different tin centres and their oxidation states were confirmed by 119Sn Mössbauer spectroscopy. In addition, the comparison between experimental and simulated X-ray powder diffraction patterns confirmed the authenticity of the samples. Our crystallographic results for (1)-(4) show that the Sn(ii) centres are tetracoordinated and exhibit distorted disphenoidal geometries, corroborating the presence of one stereochemically active lone electron pair at each metal site. Products (1) and (2) display bi-dimensional polymeric structures, (3) exhibits a one-dimensional architecture, whereas (4) shows a remarkable three-dimensional coordination network. Hirshfeld surface and supramolecular analyses for the repeating units of (1)-(4) were also performed in order to identify structurally important non-covalent interactions.

Catalysis of vegetable oil transesterification by Sn(II)-exchanged Keggin heteropolyacids: bifunctional solid acid catalysts

Keggin heteropolyacid protons (i.e., H3PW12O40, H3PMo12O40, H4SiW12O40) were partially exchanged with Sn(II) cations generating solid acid catalysts that were used for vegetable oil transesterification reactions. These catalysts have double acidity properties, i.e., Lewis acidity and Bronsted acidity that are suitable for the conversion of vegetable oil into biodiesel. The highest efficiency (ca. 100%) was achieved on the Sn1.2H0.6PW12O40-catalyzed transesterification reactions. The relationship between the catalytic activity and acidic properties was deeply discussed and the effects of main reaction parameters were assessed. The activity of the precursor HPA, tin salts and physical mixture were compared and confirmed a synergism between Sn(II) cations and PW12O40 3− anions. The reusability of catalyst was investigated.

Monte Carlo simulations of disorder in ZnSnN2 and the effects on the electronic structure

In multinary compound semiconductors, cation disorder can decisively alter the electronic properties and impact potential applications. $\mathrm{ZnSn}{\mathrm{N}}_{2}$ is a ternary nitride of interest for photovoltaics, which forms in a wurtzite-derived crystal structure. In the ground state, every N anion is coordinated by two Zn and two Sn cations, thereby observing the octet rule locally. Using a motif-based model Hamiltonian, we performed Monte Carlo simulations that provide atomistic representations of $\mathrm{ZnSn}{\mathrm{N}}_{2}$ with varying degrees of cation disorder. Subsequent electronic structure calculations describe the evolution of band gaps, optical properties, and carrier localization effects as a function of the disorder. We find that octet-rule conserving disorder is practically impossible to avoid but perfectly benign, with hardly any effects on the electronic structure. In contrast, a fully random cation distribution would be very detrimental, but fortunately it is energetically highly unfavorable. A degree of disorder that can realistically be expected for nonequilibrium thin-film deposition leads to a moderate band-gap reduction and to moderate carrier localization effects. Comparing the simulated structures with experimental samples grown by sputtering, we find evidence that these samples indeed incorporate a certain degree of octet-rule violating disorder, which is reflected in the x-ray diffraction and in the optical absorption spectra. This study demonstrates that the electronic properties of $\mathrm{ZnSn}{\mathrm{N}}_{2}$ are dominated by changes of the local coordination environments rather than long-range ordering effects.

Synthesis and ionic conductivity of NASICON - structured LiTi2-xSnx (PO4)3 anode material for lithium - ion batteries

Advanced Li-ion batteries with high rate properties are highly in demand and have generated much attention in the research community. Here, we present a simple solid-state reaction to synthesise NASICON-structured LiTi2 − xSnx (PO4)3 (x = 0–1.8) as anode material for lithium ion batteries. Their structures were determined from X-ray powder diffraction using Rietveld analysis. All the compositions present the space group R-3c. The refinements show that theta and Sn cations are statistically distributed over the same position while the Li ones are exclusively located on the M1site. The lattice constants a and c exhibit linear variation over the whole composition range. The bond lengths are in accordance with those of other NASICON structures. The SEM micrographs of the samples show relative porous microstructures. The ionic conductivity is about 10−4–10−5 (S. cm−1); for the activation energy, a typical value of 0.30 (eV) is obtained for x = 0.8 composition whereas significant deviation from linearity in the temperature dependence of the dc conductivity, is observed for the Sn- rich ones. This tendency is discussed along with the structural features.

Sn promoted BaFeO3−δ catalysts for N2O decomposition: Optimization of Fe active centers

A series of BaFe1−xSnxO3−δ catalysts were prepared by sol-gel method and tested for N2O decomposition to shed light on the effect of B-site substitution on the catalytic behavior of perovskite catalysts. 119Sn and 57Fe Mössbauer results confirmed that the 5-fold coordinated Fe3+ cations with one adjacent oxygen vacancy (Fe3+O5) were the main active centers for N2O decomposition. Doping of Sn cations can significantly improve the percentage of Fe3+O5 from 30% (x=0) to 68% (x=0.8). More importantly, the valence state of Fe could be gradually reduced due to weakening of FeO bond with increasing the Sn content, which was attributed to the stronger force of Sn than Fe in FeOSn structure to draw the oxygen anion and expansion of unit cell volume. Such change of Fe chemical state favored the oxygen mobility of the catalyst, leading to reduction in activation energy for N2O decomposition from ca. 241 (x=0) to 178kJmol−1 (x=0.8). BaFe0.2Sn0.8O3−δ catalyst exhibited the highest intrinsic rate of 1.49s−1 (550°C), nearly 4 times larger than that of BaFeO3−δ (0.43s−1).

Electrochemical synthesis and physical properties of Sn-doped CdO nanostructures

Un- and Sn-doped CdO thin films were deposited on FTO-coated glass substrates using electrodeposition method. Crystalline study revealed a cubic phase for all samples. SEM images showed flower- and rod-like morphologies for the Sn-doped samples in nano-dimensions. Optical energy band gaps of 2.70, 2.79, and 2.84 eV were obtained for Sn0, Sn1, and Sn2 samples, respectively. Electrical investigations indicted that CdO thin films revealed n-type conductivity with high density of donor levels, which exceeded by corporation of Sn cations in the crystalline structures of CdO thin films.

Mild Synthesis of Pt/SnO2 /Graphene Nanocomposites with Remarkably Enhanced Ethanol Electro-oxidation Activity and Durability.

We have designed a new Pt/SnO2 /graphene nanomaterial by using L-arginine as a linker; this material shows the unique Pt-around-SnO2 structure. The Sn(2+) cations reduce graphene oxide (GO), leading to the in situ formation of SnO2 /graphene hybrids. L-Arginine is used as a linker and protector to induce the in situ growth of Pt nanoparticles (NPs) connected with SnO2 NPs and impede the agglomeration of Pt NPs. The obtained Pt/SnO2 /graphene composites exhibit superior electrocatalytic activity and stability for the ethanol oxidation reaction as compared with the commercial Pt/C catalyst owing to the close-connected structure between the Pt NPs and SnO2 NPs. This work should have a great impact on the rational design of future metal-metal oxide nanostructures with high catalytic activity and stability for fuel cell systems.