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COMMON PART

Project Number23-23-00583

Project titleDevelopment of green methods for the synthesis of functional materials based on germanium compounds from highly soluble germanium oxide

Project LeadMedvedev Alexander

AffiliationKurnakov Institute of General and Inorganic Chemistry RAS,

Research area 03 - CHEMISTRY AND MATERIAL SCIENCES, 03-201 - Synthesis, structure, and reactivity of inorganic compounds

KeywordsGermanium oxide, ammonium peroxogermanate, coordination chemistry, inorganic chemistry, methods for obtaining inorganic substances and materials, green chemistry, functional materials

PROJECT CONTENT

Annotation
The properties of germanium and its compounds determine its wide application in various fields of science and technology. For example, germanium is transparent in the IR region and is used to make optical lenses and glasses; germanium dioxide has a high refractive index and low optical dispersion and is used to manufacture optical systems, in particular fiber optics [1]. In addition, germanium compounds and materials based on them are used in the production of electronic components, semiconductors and photovoltaic systems, as well as a polymerization catalyst in the production of polyethylene terephthalate. The main methods for obtaining germanium compounds based functional materials mainly involve the use of germanium(IV) halides and alkoxides as starting compounds, which requires the disposal of formed acidic and other toxic wastes. In addition, the widely used solvothermal synthesis methods are associated with the use of expensive equipment, large volumes of organic solvents, and low product yields. This greatly increases their cost. The use of GeO2 as a starting reagent is also limited due to its low solubility in water (0.43 g per 100 g H2O at 20°С). It should be noted that germanium(IV) oxide usually contains an admixture of halides, which requires additional purification steps and reduces the yield of the final product. On the other hand, germanium compounds are expensive reagents, which determines the need to develop production methods with a quantitative yield in terms of germanium. This is the reason for the search for new convenient starting compounds of germanium with high reactivity and good solubility in water, in comparison with known precursors. The project is aimed at solving the scientific problem of modern chemistry of materials associated with the development of environmentally safe and inexpensive methods for obtaining functional materials based on germanium compounds with a yield close to 100%. In this case, use highly soluble germanium oxide (HSGO) as the initial germanium compound, which is obtained by rapid decomposition of ammonium peroxogermanate (NH4)6[Ge6(μ-OO)6(μ-O)6-( OH)6] 6H2O at 300°C is proposed. Previously, it was shown that HSGO has a high solubility (up to 100 g per 1 L of water) and reactivity and, therefore, is a convenient starting reagent for the preparation of various germanium compounds [1]. However, until now, HSGO has not been used to obtain functional materials containing germanium compounds, which is the reason for the scientific novelty of this project. The solution of this problem will make it possible to propose new methods for the synthesis of functional materials based on germanium compounds. The use of a highly soluble form of amorphous germanium oxide will increase the germanium yield to a quantitative level, and also opens up new possibilities for controlling the morphology and composition of composite materials during the synthesis. One of the tasks of the project is related to the selection of optimal conditions for the controlled crystallization of hexagonal germanium oxide of various morphologies as a separate phase and on substrates of various compositions, including graphene oxide. The second task is related to the study of the reactivity of GeO2 of various morphologies as a separate phase and as part of composite materials in order to develop methods for obtaining materials based on GeS2, Ge3N4, and other germanium compounds. In addition, in the course of the project, solve the problem of studying the functional properties of a number of obtained materials is proposed. In particular, study the materials in the electrode materials of metal-ion batteries and gas sensors is proposed. This will make it possible to establish the relationship between the properties of the obtained materials and the method of their preparation and to evaluate the feasibility of using highly soluble amorphous germanium oxide as the initial compound. For the successful implementation of the project, it is proposed to apply a number of original synthetic methods and approaches. Thus, the proposed project is aimed at solving an actual modern scientific problem and will allow to develop green methods for obtaining functional materials based on germanium oxide, sulfide and other compounds for use as electrode materials in metal-ion batteries, gas sensors and other applications. Highly soluble germanium oxide is supposed to be used as the starting compound. 1. Grishanov D.A., Churakov A.V., Medvedev A.G., Mikhaylov A.A., Lev O., Prikhodchenko P.V. Inorganic Chemistry 2019, 58 (3), 1905-1911. DOI:10.1021/acs.inorgchem.8b02747.

Expected results
In the course of this project, green methods for obtaining functional materials based on germanium compounds using highly soluble germanium oxide as a starting compound will be developed. The new methods will allow to obtain functional materials of various compositions and morphologies with a quantitative yield on germanium and without the use of large amounts of organic solvents, without heating the reaction solutions, and without the use of expensive equipment. The optimal conditions for the controlled crystallization of hexagonal germanium oxide will be determined and materials of various morphologies in the form of separate phases and on substrates of various compositions, including graphene oxide will be obtained. The resulting materials will be used for the subsequent synthesis of materials based on germanium compounds The reactivity of GeO2 of various morphologies as a separate phase and as part of composite materials will be studied in order to develop methods for obtaining materials based on GeS2, Ge3N4 and other germanium compounds. All received materials will be studied by a set of physical and chemical methods of analysis. In addition, the properties of a number of obtained materials will be studied, including those in the composition of electrode materials of lithium- and sodium-ion batteries. Cycling stability and rate dependences will be obtained for prepared materials as metal-ion battery anodes. Cyclic voltyammetry will be carried out to study the electrochemical processes during the interaction of lithium and sodium with electrode material . The functional properties of a number of obtained materials in the composition of gas sensor electrodes will be investigated. Values of sensitivity and response time will be obtained when various amounts of hazardous gases (hydrogen, hydrogen sulfide, nitrogen oxides, ammonia, methane, etc.) are introduced into the atmosphere. Based on the obtained results, the feasibility of using highly soluble amorphous germanium oxide as a starting compound for obtaining functional materials based on germanium compounds (oxide, sulfide, nitride, phosphide, etc.) will be evaluated.

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