Petr V. Prikhodchenko

High-capacity antimony sulphide nanoparticle-decorated graphene composite as anode for sodium-ion batteries

Sodium-ion batteries are an alternative to lithium-ion batteries for large-scale applications. However, low capacity and poor rate capability of existing anodes are the main bottlenecks to future developments. Here we report a uniform coating of antimony sulphide (stibnite) on graphene, fabricated by a solution-based synthesis technique, as the anode material for sodium-ion batteries. It gives a high capacity of 730 mAh g(-1) at 50 mA g(-1), an excellent rate capability up to 6C and a good cycle performance. The promising performance is attributed to fast sodium ion diffusion from the small nanoparticles, and good electrical transport from the intimate contact between the active material and graphene, which also provides a template for anchoring the nanoparticles. We also demonstrate a battery with the stibnite-graphene composite that is free from sodium metal, having energy density up to 80 Wh kg(-1). The energy density could exceed that of some lithium-ion batteries with further optimization.

Nanocrystalline tin disulfide coating of reduced graphene oxide produced by the peroxostannate deposition route for sodium ion battery anodes

A highly stable sodium ion battery anode was prepared by deposition of hydroperoxostannate on graphene oxide from hydrogen-peroxide-rich solution followed by sulfidization and 300 °C heat treatment. The material was characterized by electron microscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy which showed that the active material is mostly rhombohedral SnS2 whose (001) planes were preferentially oriented in parallel to the graphene oxide sheets. The material exhibited >610 mA h g−1 charge capacity at 50 mA g−1 (with >99.6% charging efficiency) between 0 and 2 V vs. Na/Na+ electrode, high cycling stability for over 150 cycles and very good rate performance, >320 mA h g−1 at 2000 mA g−1.

Peroxide induced tin oxide coating of graphene oxide at room temperature and its application for lithium ion batteries

We describe a new, simple and low-temperature method for ultra-thin coating of graphene oxide (GO) by peroxostannate, tin oxide or a mixture of tin and tin oxide crystallites by different treatments. The technique is environmentally friendly and does not require complicated infrastructure, an autoclave or a microwave. The supported peroxostannate phase is partially converted after drying to crystalline tin oxide with average, 2.5 nm cassiterite crystals. Mild heat treatment yielded full coverage of the reduced graphene oxide by crystalline tin oxide. Extensive heat treatment in vacuum at >500 °C yielded a mixture of elemental tin and cassiterite tin oxide nanoparticles supported on reduced graphene oxide (rGO). The usefulness of the new approach was demonstrated by the preparation of two types of lithium ion anodes: tin oxide-rGO and a mixture of tin oxide and tin coated rGO composites (SnO(2)-Sn-rGO). The electrodes exhibited stable charge/discharge cyclability and high charging capacity due to the intimate contact between the conductive graphene and the very small tin oxide crystallites. The charging/discharging capacity of the anodes exceeded the theoretical capacity predicted based on tin lithiation. The tin oxide coated rGO exhibited higher charging capacity but somewhat lower stability upon extended charge/discharge cycling compared to SnO(2)-Sn-rGO.

Crystal structures of natural amino acid perhydrates

The structures of various natural amino acid hydrogen peroxide solvates are presented. All “active” hydrogen atoms (amino, hydroxy, peroxy, and water) in the studied amino acid perhydrates are involved in hydrogen bonding. Peroxide molecules form at least two donor hydrogen bonds. In the most common case, the H2O2 molecule is engaged in four hydrogen bonds (two donors with –CO2−groups and two acceptors with –NH3+groups). In peroxosolvates of amino acids bearing hydrocarbon side-chains, double layers were observed. These bilayers are hydrophilic inside, while their outer surfaces are hydrophobic. It was found that donor hydrogen bonds formed by hydrogen peroxide in amino acid perhydrates are significantly stronger than those formed by water molecules in amino acid hydrates.

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.

Zinc dioxide nanoparticulates: a hydrogen peroxide source at moderate pH.

Solid peroxides are a convenient source of hydrogen peroxide, which once released can be readily converted to active oxygen species or to dissolved dioxygen. A zinc peroxide nanodispersion was synthesized and characterized, and its solubility was determined as a function of pH and temperature. We show that zinc peroxide is much more stable in aqueous solutions compared to calcium and magnesium peroxides and that it retains its peroxide content down to pH 6. At low pH conditions H2O2 release is thermodynamically controlled and its dissolution product, Zn(2+), is highly soluble, and thus, hydrogen peroxide release can be highly predictable. The Gibbs free energy of formation of zinc peroxide was found to be -242.0 ± 0.4 kJ/mol and the enthalpy of formation was -292.1 ± 0.7 kJ/mol, substantially higher than theoretically predicted before. The biocidal activity of zinc peroxide was determined by inactivation studies with Escherichia coli cultures, and the activity trend agrees well with the thermodynamic predictions.

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.

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.

The preparation and crystal structures of novel perhydrates Ph4X+Hal−·nH2O2: anionic hydrogen-bonded chains containing hydrogen peroxide

Eight novel perhydrates Ph4X+Hal−·nH2O2 (X = P, As; Hal = Cl, Br; n = 0.98–1.90) were prepared and their structures were determined by X-ray crystallography. All the structures are formed by parallel infinite zigzag chains of Ph4X+ cations and hydrogen-bonded anionic chains [(H2O2)x(Hal−)y]∞ (x, y = 1, 2). Hydrogen peroxide is partially substituted by admixed water molecules. Some of the studied perhydrates were found to be isostructural with the related hydrates Ph4X+Hal−·nH2O.

GeO2 Thin Film Deposition on Graphene Oxide by the Hydrogen Peroxide Route: Evaluation for Lithium-Ion Battery Anode

A peroxogermanate thin film was deposited in high yield at room temperature on graphene oxide (GO) from peroxogermanate sols. The deposition of the peroxo-precursor onto GO and the transformations to amorphous GeO2, crystalline tetragonal GeO2, and then to cubic elemental germanium were followed by electron microscopy, XRD, and XPS. All of these transformations are influenced by the GO support. The initial deposition is explained in view of the sol composition and the presence of GO, and the different thermal transformations are explained by reactions with the graphene support acting as a reducing agent. As a test case, the evaluation of the different materials as lithium ion battery anodes was carried out revealing that the best performance is obtained by amorphous germanium oxide@GO with >1000 mAh g-1 at 250 mA g-1 (between 0 and 2.5 V vs Li/Li+ cathode), despite the fact that the material contained only 51 wt % germanium. This is the first demonstration of the peroxide route to produce peroxogermanate thin films and thereby supported germanium and germanium oxide coatings. The advantages of the process over alternative methodologies are discussed.