Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide.

Germanium and germanium-based compounds are widely used in microelectronics, optics, solar cells, and sensors. Recently, germanium and its oxides, nitrides, and phosphides have been studied as active electrode materials in lithium- and sodium-ion battery anodes. Herein, the newly introduced highly soluble germanium oxide (HSGO) was used as a versatile precursor for germanium-based functional materials. In the first stage, a germanium-dioxide-reduced graphene oxide (rGO) composite was obtained by complete precipitation of GeO2 nanoparticles on the GO from an aqueous solution of HSGO and subsequent thermal treatment in argon at low temperature. The composition of the composite, GeO2-rGO (20 to 80 wt.% of crystalline phase), was able to be accurately determined by the HSGO to GO ratio in the initial solution since complete deposition and precipitation were achieved. The chemical activity of germanium dioxide nanoparticles deposited on reduced graphene oxide was shown by conversion to rGO-supported germanium nitride and phosphide phases. The GeP-rGO and Ge3N4-rGO composites with different morphologies were prepared in this study for the first time. As a test case, composite materials with different loadings of GeO2, GeP, and Ge3N4 were evaluated as lithium-ion battery anodes. Reversible conversion-alloying was demonstrated in all cases, and for the low-germanium loading range (20 wt.%), almost theoretical charge capacity based on the germanium content was attained at 100 mA g-1 (i.e., 2595 vs. 2465 mAh g-1 for Ge3N4 and 1790 vs. 1850 mAh g-1 for GeP). The germanium oxide was less efficiently exploited due to its lower conversion reversibility.

Triphenyllead Hydroperoxide: A 1D Coordination Peroxo Polymer, Single-Crystal-to-Single-Crystal Disproportionation to a Superoxo/Hydroxo Complex, and Application in Catalysis.

The synthesis, transformation, and application in catalysis of triphenyllead hydroperoxide, the first dioxygen lead complex, are described. Triphenyllead hydroperoxide is characterized by 207Pb nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and single-crystal X-ray diffraction, revealing the first one-dimensional (1D) coordination peroxo polymer. Photolytic isomorphous transformation of Ph3PbOOH yields a mixed hydroxo/superoxo crystalline structure, the first nonalkali superoxo crystalline metal salt, which is stable up to 100 °C. Upon further photolysis, another isomorphous transformation of the superoxide to hydroxide is observed. These are the first single-crystal-to-single-crystal hydroperoxide-to-superoxide and then to hydroxide transformations reported to date. Photolysis of triphenyllead hydroperoxide yields two forms of superoxide-doped crystalline structures that are distinguished by widely different characteristic relaxation times. The use of Ph3PbOOH as an easy-to-handle solid two-electron oxidant for the highly enantioselective epoxidation of olefins is described.

Identification of Barium Hydroxo-Hydroperoxostannate Precursor for Low-Temperature Formation of Perovskite Barium Stannate.

A breakthrough "superoxide colloidal solution route" for low-temperature synthesis of barium and strontium stannate perovskites and their doped analogues was recently introduced. The synthesis starts from hydrogen peroxide-rich stannate solutions and yields a so-called "crystalline superoxide molecular cluster" that is converted by low temperature (<300 °C) to the respective perovskites. In this paper, the so-called "crystalline superoxide molecular cluster" is identified as a superoxide-free, barium trihydroxo(hydroperoxo)peroxostannate, BaSn(OH)3(OOH)(OO) phase (BHHPS). EPR and Raman spectroscopy studies reveal the absence of superoxide in this crystalline phase. FTIR of the deuterated sample, 119Sn NMR, and elemental analysis uncovered the empirical formula, H4O7SnBa with two peroxides per each tin element. Rietveld refinement of the XRD confirms the BHHPS cubic phase with replacement of the perovskite oxygen atoms by the OH- and OOH-ligands and peroxobridging groups.

H2O2 induced formation of graded composition sodium-doped tin dioxide and template-free synthesis of yolk-shell SnO2 particles and their sensing application.

Sodium peroxostannate nanoparticles with graded composition were produced from aqueous hydrogen peroxide-sodium hydroxostannate solution. The uniform particles were converted to composition graded sodium stannate by mild thermal treatment for peroxide decomposition and yielded yolk-shell tin dioxide particles by dilute acid treatment. The mechanism of formation of the graded sodium concentration is explained in view of the solubility of peroxostannate in H2O2-H2O solution and based on 119Sn NMR, XRD, dynamic light scattering (DLS) and electron microscopy studies. Initial studies illuminating sensitive hydrogen sensing by yolk-shell tin oxide particles are presented.

Potassium, Cesium, and Ammonium Peroxogermanates with Inorganic Hexanuclear Peroxo Bridged Germanium Anion Isolated from Aqueous Solution.

Potassium (K6[Ge6(µ-OO)6(µ-O)6(OH)6]·14H2O, 1), cesium ammonium (Cs4.2(NH4)1.8[Ge6(µ-OO)6(µ-O)6(OH)6]·8H2O, 2), and potassium ammonium (K2.4(NH4)3.6[Ge6(µ-OO)6(µ-O)6(OH)6]·6H2O, 3) peroxogermanates were isolated from 3% hydrogen peroxide aqueous solutions of the corresponding hydroxogermanates and characterized by single crystal and powder X-ray diffraction studies and by Raman spectroscopy and thermal analysis. The crystal structure of all three compounds consists of cations of potassium and/or ammonium and cesium, water molecules, and centrosymmetric hexanuclear peroxogermanate anion [Ge6(µ-OO)6(µ-O)6(OH)6](6-) with six µ-oxo- and six µ-peroxo groups. Peroxogermanates demonstrate relatively high thermal stability: the peroxide remains in the structure even after water release after heating to 100-120 °C. DFT calculations of the peroxogermanate [Ge6(µ-OO)6(µ-O)6(OH)6](6-) anion confirm its higher thermodynamic stability compared to the hydroperoxo- and oxogermanate analogues.

H-bond network in amino acid cocrystals with H2O or H2O2. The DFT study of serine-H2O and serine-H2O2.

The structure, IR spectrum, and H-bond network in the serine-H(2)O and serine-H(2)O(2) crystals were studied using DFT computations with periodic boundary conditions. Two different basis sets were used: the all-electron Gaussian-type orbital basis set and the plane wave basis set. Computed frequencies of the IR-active vibrations of the titled crystals are quite different in the range of 10-100 cm(-1). Harmonic approximation fails to reproduce IR active bands in the 2500-2800 frequency region of serine-H(2)O and serine-H(2)O(2). The bands around 2500 and 2700 cm(-1) do exist in the anharmonic IR spectra and are caused by the first overtone of the OH bending vibrations of H(2)O and a combination vibration of the symmetric and asymmetric bendings of H(2)O(2). The quantum-topological analysis of the crystalline electron density enables us to describe quantitatively the H-bond network. It is much more complex in the title crystals than in a serine crystal. Appearance of water leads to an increase of the energy of the amino acid-amino acid interactions, up to ~50 kJ/mol. The energy of the amino acid-water H-bonds is ~30 kJ/mol. The H(2)O/H(2)O(2) substitution does not change the H-bond network; however, the energy of the amino acid-H(2)O(2) contacts increases up to 60 kJ/mol. This is caused by the fact that H(2)O(2) is a much better proton donor than H(2)O in the title crystals.

A model proton-transfer system in the condensed phase: NH4(+)OOH(-), a crystal with short intermolecular H-bonds.

The crystal structure of NH(4)(+)OOH(-) is determined from single-crystal x-ray data obtained at 150 K. The crystal belongs to the space group P2(1)/c and has four molecules in a unit cell. The structure consists of discrete NH(4)(+) and OOH(-) ions. The OOH(-) ions are linked by short hydrogen bonds (2.533 Å) to form parallel infinite chains. The ammonium ions form links between these chains (the N⋯O distances vary from 2.714 to 2.855 Å) giving a three-dimensional network. The harmonic IR spectrum and H-bond energies are computed at the Perdew-Burke-Ernzerhof (PBE)/6-31G(∗∗) level with periodic boundary conditions. A detailed analysis of the shared (bridging) protons' dynamics is obtained from the CPMD simulations at different temperatures. PBE functional with plane-wave basis set (110 Ry) is used. At 10 K the shared proton sits near the oxygen atom, only a few proton jumps along the chain are detected at 70 K while at 270 K numerous proton jumps exist in the trajectory. The local-minimum structure of the space group Cc is localized. It appears as a result of proton transfer along a chain. This process is endothermic (∼2 kJ/mol) and is described as P2(1)/c↔2Cc. The computed IR spectrum at 10 K is close to the harmonic one, the numerous bands appear at 70 K while at 270 K it shows a very broad absorption band that covers frequencies from about 1000 to 3000 cm(-1). The advantages of the NH(4)(+)OOH(-) crystal as a promising model for the experimental and DFT based molecular dynamics simulation studies of proton transfer along the chain are discussed.

Antimony tin oxide (ATO) nanoparticle formation from H2O2 solutions: a new generic film coating from basic solutions.

A generic method for conductive film coating of minerals and acid-sensitive materials by antimony-doped tin oxide (ATO) is introduced. The coating was performed from a hydrogen peroxide stabilized stannate and antimonate precursor solution. This is the first demonstration of ATO coating from an organic ligand-free solution. Uniform coating of different clays and other irregular configurations by monosized 5 nm ATO particles was demonstrated. The deposition mechanism and the observed preference for mineral surface coating over homogeneous agglomeration of the tin oxide particles are explained by a hydrogen peroxide capping mechanism and hydrogen bonding of the hydroperoxo nanoparticles to the H(2)O(2)-activated mineral surfaces.

Cesium hydroperoxostannate: first complete structural characterization of a homoleptic hydroperoxocomplex.

The crystal structure of cesium hexahydroperoxostannate Cs(2)Sn(OOH)(6) is presented. The compound was characterized by single crystal and by powder X-ray diffraction, FTIR, (119)Sn MAS NMR, and TG-DTA. Cs(2)Sn(OOH)(6) crystallizes in the trigonal space group P3, a = 7.5575(4), c = 5.1050(6) A, V = 252.51(4) A(3), Z = 1, R(1) = 0.0120 (I > 2sigma(I)), wR(2) = 0.0293 (all data), and comprises cesium cations and slightly distorted octahedral [Sn(OOH)(6)](2-) anions lying on the threefold axis. The [Sn(OOH)(6)](2-) unit forms 12 interanion hydrogen bonds resulting in anionic chains spread along the c-axis. All six hydroperoxo ligands are crystallographically equivalent; O-O distances are 1.482(2), only slightly longer than the O-O distance in hydrogen peroxide. FTIR and (119)Sn MAS NMR reveal the similarity between all alkali hydroperoxostannates.