In this work, we tried to combine the advantages of microemulsion and emulsion synthesis to obtain stable concentrated organosols of Ag nanoparticles, promising liquid-phase materials. Starting reagents were successively introduced into a micellar solution of sodium bis-(2-ethylhexyl)­sulfosuccinate (AOT) in n-decane in the dynamic reverse emulsion mode. During the contact of the phases, Ag+ passes into micelles and Na+ passes into emulsion microdroplets through the cation exchange AOTNaOrg + AgNO3 Aq = AOTAgOrg + NaNO3 Aq. High concentrations of NaNO3 and hydrazine in the microdroplets favor an osmotic outflow of water from the micelles, which reduces their polar cavities to ∼2 nm. As a result, silver ions are contained in the micelles, and the reducing agent is present mostly in emulsion microdroplets. The reagents interact in the polar cavities of micelles to form ∼7 nm Ag nanoparticles. The produced nanoparticles are positively charged, which permitted their electrophoretic concentration to obtain liquid concentrates (up to 30% Ag) and a solid Ag–AOT composite (up to 75% Ag). Their treatment at 250 °C leads to the formation of conductive films (180 mOhm per square). The developed technique makes it possible to increase the productivity of the process by ∼30 times and opens up new avenues of practical application for the well-studied microemulsion synthesis.

A comparative analysis of the chemiresistive sensor response of thin films of a series of tetrasubstituted phthalocyanines of various metals with F-substituent in peripheral (MPcF4-p, M = Cu, Co, Zn, Pb, VO) and non-peripheral (MPcF4-np) positions in macroring to low concentrations of ammonia (1–50 ppm) was carried out. It was found that MPcF4-p films exhibit a higher sensor response than MPcF4-np ones. A CoPcF4-p film demonstrated a calculated LOD of 0.01 ppm with a recovery time of 215 s, while a VOPcF4-p film had LOD of 0.04 ppm and the recovery time of 270 s. The selectivity test showed that CO2, ethanol, acetone, benzene, and formaldehyde did not interfere with the determination of ammonia, while H2S at a concentration of more than 10 ppm could act as an interfering gas. It was shown that, as a result of quantum-chemical calculations, the observed regularities are best described by the interaction of NH3 with phthalocyanines through the formation of hydrogen bonds between NH3 and side atoms of the macroring. In the case of MPcF4-p, the NH3 molecule approaches the macrocycle more closely and binds more strongly than in the case of MPcF4-np. The stronger binding leads to a stronger effect of the ammonia molecule on the electronic structure of phthalocyanine and, as a consequence, on the chemiresistive sensor response of the films to ammonia.

The systematic study of the platinum speciation in sulfuric acid solutions of platinum (IV) hydroxide { [Pt-(OH) 4 (H 2 O) 2 ], HHPA} was performed with the use of a combination of methods. Depending on the prevailing Pt form, the three regions of H 2 SO 4 concentration were marked: (1) up to 3 M H 2 SO 4 forms unstable solutions gradually generating the PtO 2 • xH 2 O particles; (2) 4−12 M H 2 SO 4 , where the series of mononuclear aqua−sulfato complexes ([Pt(SO 4 ) n (H 2 O) 6−n ] 4−2n , where n = 0•••4) dominate; and (3) 12 M and above, where, along with [Pt(SO 4 ) n (H 2 O) 6−n ] 4−2n species, the polynuclear Pt(IV) species and complexes with a bidentate coordination mode of the sulfato ligand are formed. For the first time, the salts of the aqua−hydroxo Pt(IV) cation [Pt(OH) 2 (H 2 O) 4 ]SO 4 (triclinic and monoclinic phases) were isolated and studied with a combination of methods, including the single-crystal X-ray diffraction. The formation of PtO 2 •xH 2 O particles in sulfuric acid solutions (1−3 M) of HHPA and their spectral characteristics and morphology were studied. The deposition of PtO 2 •xH 2 O was highlighted as a convenient method to prepare various Pt-containing heterogeneous catalysts. This possibility was illustrated by the preparation of Pt/g-C 3 N 4 catalysts, which show an excellent performance in catalytic H 2 generation under visible light irradiation with a quantum efficiency up to 5% and a rate of H 2 evolution up to 6.2 mol•h −1 per gram of loaded platinum.