Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2

Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding material properties. These properties mainly rely on maximizing the number of strong covalent bonds, with crosslinked XN₆ octahedra frameworks being particularly attractive. In this study, the phosphorus–nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells, and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. δ-P₃N₅ and PN₂ were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN₆ units. The two compounds are ultra-incompressible, having a bulk modulus of K₀=322 GPa for δ-P₃N₅ and 339 GPa for PN₂. Upon decompression below 7 GPa, δ-P₃N₅ undergoes a transformation into a novel α′-P₃N₅ solid, stable at ambient conditions, that has a unique structure type based on PN₄ tetrahedra. The formation of α′-P₃N₅ underlines that a phase space otherwise inaccessible can be explored through materials formed under high pressure.     

Photochemical oxidation of persistent cyanide-related compounds

Russian Journal of Physical Chemistry A - Kinetic regularities of the photolysis of thiocyanate solutions using of mono- and polychromatic UV radiation sources with different spectral ranges are...     

Cavitational activation of the galvanochemical oxidation of phenol

Possibility of intensifying the galvanochemical oxidation of phenol under hydrodynamic cavitation conditions was studied.     

Catalytic destruction of organic contaminants by galvanochemical oxidation

The possibility of intensifying the catalytic destruction of phenol by galvanochemical oxidation was confirmed experimentally. The treatment time can be reduced due to the sluggish occurrence of chain radical oxidation (aftereffect). The oxidation can be performed in less acidic media in the presence of chlorides. The possibility of increasing the efficiency of oxidation by introducing H₂O₂ in the reaction zone in doses and reducing the undesired reactions of the oxidant was confirmed experimentally.     

High‐Pressure Synthesis of Metal–Inorganic Frameworks Hf4N20⋅N2, WN8⋅N2, and Os5N28⋅3 N2 with Polymeric Nitrogen Linkers

Polynitrides are intrinsically thermodynamically unstable at ambient conditions and require peculiar synthetic approaches. Now, a one‐step synthesis of metal–inorganic frameworks Hf₄N₂₀?N₂, WN₈?N₂, and Os₅N₂₈?3 N₂ via direct reactions between elements in a diamond anvil cell at pressures exceeding 100 GPa is reported. The porous frameworks (Hf₄N₂₀, WN₈, and Os₅N₂₈) are built from transition‐metal atoms linked either by polymeric polydiazenediyl (polyacetylene‐like) nitrogen chains or through dinitrogen units. Triply bound dinitrogen molecules occupy channels of these frameworks. Owing to conjugated polydiazenediyl chains, these compounds exhibit metallic properties. The high‐pressure reaction between Hf and N₂ also leads to a non‐centrosymmetric polynitride Hf₂N₁₁ that features double‐helix catena‐poly[tetraz‐1‐ene‐1,4‐diyl] nitrogen chains [?N?N?N=N?]_∞.     

Photoactivation of the oxidation process of <Emphasis Type="Italic">para</Emphasis>-chlorophenol in aqueous solutions

Kinetics of the oxidative destruction of para-chlorophenol in a combined iron-persulfate system under the action of simulated sunlight was studied. It was shown that, under additional photoirradiation, a deep conversion of chlorophenol and main intermediate products of its destruction is provided, with iron compounds serving not only as catalysts, but also as photochemical oxidation sensitizers. The degree of mineralization of para-chlorophenol and products of its oxidation under a photoactivated treatment for two hours reached a value of 60%, whereas that in the “dark” reaction did not exceed 1%. In the combined oxidizing system S₂O ₈ ^2– /Fe²⁺/UV-Vis, a considerable synergic effect was observed due to the formation of reactive oxygen intermediate both via decomposition persulfate and through reduction of Fe³⁺ from inactive Fe³⁺ intermediates.     

Oxidation of atrazine by photoactivated potassium persulfate in aqueous solutions

General laws of the photochemical oxidation of atrazine by inorganic peroxo compounds under the impact of solar radiation are studied. It is found that almost complete conversion of atrazine can be achieved via photochemical oxidation with persulfate after 120 min, but no deep mineralization is observed. The effect an aqueous matrix has on the processes of atrazine degradation in combined oxidation systems is considered.     

Electrochemical oxidation of phenols

Electrochemical oxidation of chlorinated phenols was studied.     

Effect of Hydrocarbonates and Chlorides on the Photodestruction of Bisphenol A

Russian Journal of Physical Chemistry A - The effect hydrocarbonates and chlorides, the most common anions in natural and waste waters, on the oxidation of bisphenol A by persulfate activated with...