Assessing state of water protection zones of Volga River within Ilyinka village area (Astrakhan region)

Anthropogenic pollution of water basins may become a serious threat for ecosystems and human health. Pollutants are transferred through food chains or directly when untreated water is used, released to soil through subsoil waters or during floods. The increased anthropogenic load on rivers’ hydrosystems, especially in their del-tas, is becoming rampant these days. The goal of the research is to study the coastal areas and to assess the state of vegetation. To achieve this goal, standard methods of biotesting and bioindication were applied in the territories of two water-protection zones – those of the Volga River and the Nozhovskiy erik (shallow channel in the Volga delta – translator’s note) near the Ilyinka village. The water quality in the Volga River, within the examined range, is stably characterized as “dirty” (4th class). The exceeded level of maximum permissible concentrations for petroleum products, heavy metals (mercury, zinc, molybdenum), sulfides and phenols is observed. The research has not revealed the impact of the quality of water on phytotoxicity of the soil and indices of abundance of the vegetation that grows in this territory. Toxicity of soils is weak in the area of the Nozhovskiy erik, it is very weak in the area of the Volga River: the germination capacity of the test object (watercress) ranges between 67 and 88%, morpho-metric indices of plants do not differ much from those in control groups. Within the summer period the monitoring sites were characterized by the maximum frequency-abundance indices of typical representatives of the local flora, which are camel thorn (Alhagi pseudalhagi) and greater burdock (Arctium lappa). Vegetation in these areas is abundant, its state is assessed as satisfactory.

Substitution of copper atoms into defect-rich molybdenum sulfides and their electrocatalytic activity

Colloidal technique was used to synthesize copper atom substituted molybdenum sulfides and used as a catalyst. The derived materials were characterized using several analytical methods and revalidated using DFT calculations.

Structure of Nanocrystalline, Partially Disordered MoS2+δ Derived from HRTEM—An Abundant Material for Efficient HER Catalysis

Molybdenum sulfides (MoSx, x > 2) are promising catalysts for the hydrogen evolution reaction (HER) that show high hydrogen evolution rates and potentially represent an abundant alternative to platinum. However, a complete understanding of the structure of the most active variants is still lacking. Nanocrystalline MoS2+δ was prepared by a solvothermal method and immobilized on graphene. The obtained electrodes exhibit stable HER current densities of 3 mA cm−2 at an overpotential of ~200 mV for at least 7 h. A structural analysis of the material by high-resolution transmission electron microscopy (HRTEM) show partially disordered nanocrystals of a size between 5–10 nm. Both X-ray and electron diffraction reveal large fluctuations in lattice spacing, where the average c-axis stacking is increased and the in-plane lattice parameter is locally reduced in comparison to the layered structure of crystalline MoS2. A three-dimensional structural model of MoS2+δ could be derived from the experiments, in which [Mo2S12]2− and [Mo3S13]2− clusters as well as disclinations represent the typical defects in the ideal MoS2 structure. It is suggested that the partially disordered nanostructure leads to a high density of coordinatively modified Mo sites with lower Mo–Mo distances representing the active sites for HER catalysis, and, that these structural features are more important than the S:Mo ratio for the activity.