A. K. Gatin

Interaction of hydrogen and oxygen on the surface of individual gold nanoparticles

Adsorption properties of gold nanoparticles on pyrolytic graphite were studied. Water molecules are formed due to the consecutive adsorption of hydrogen and oxygen on the nanoparticle surface. The energies of bonds between chemisorbed hydrogen, water, and gold were determined.

Adsorption and interaction of hydrogen and oxygen on the surface of separate crystalline gold nanoparticles

Crystalline 4- to 5-nm gold nanoparticles supported on graphite and oxidized silicon have been obtained by the impregnation method. Specific features of the adsorption and interaction of H2 and O2 on the Au surface have been investigated by scanning tunneling microscopy, Auger electron spectroscopy, and mass spectrometry. Hydrogen adsorbs dissociatively on separate Au nanoparticles. The Au-H bond energy is ∼1.7 eV. Oxygen adsorbs on the separate Au nanoparticles after hydrogen adsorption. The support nature has a significant effect on the reactivity of the H2 and O2 molecules adsorbed on the surface of the Au nanoparticles. A sufficient condition for water formation from oxygen and hydrogen on Au/SiO2/Si is that Au/SiO2/Si is exposed to H2 and then to O2. As distinct from what is observed for Au/SiO2/Si, water on the Au/graphite surface forms solely due to the successive adsorption of H2, O2, and H2.

Interaction of ammonia with organoboron nanoparticle-based coatings

The interaction between ammonia and (C2B10H4)n nanoparticle-coated and uncoated graphite plates combined with molybdenum surface heated to 700 K was investigated. It was found that in both cases the interaction leads to the decomposition of ammonia into hydrogen and nitrogen; however, the presence of organoboron nanoparticles (OBN) accelerates this process. The tunneling current-voltage dependences of the nanoparticles before and after interaction with NH3 were measured. The close similarity of the measured I–V curves suggests that the interaction preserves the organoboron-nanoparticle electronic structure.

Structure and Physicochemical Properties of Nanostructured Metal Oxide Films for Use as the Sensitive Layer in Gas Sensors

The morphological features of nanostructured films of tin, zinc, indium, and cerium oxides are established. The parameters of electron traps, such as adsorbed oxygen atoms and structural defects, responsible for the sensory effect are determined. An increase in the conductance of indium oxide films upon annealing in vacuum is revealed.

Adsorption properties of nanoparticles

Scanning tunneling microscopy and spectroscopy, Auger spectroscopy, and mass spectrometry were used to study the physicochemical properties of nanoparticles of several metals and their oxides. The adsorption properties of the nanoparticles were determined for their interaction with hydrogen, oxygen, and nitrogen.

Effect of the substrate material on the catalytic decomposition of ammonia on organoboron nanoparticles

The catalytic decomposition of ammonia on (C2B10H4)n organoboron nanoparticles deposited onto SiO2, Al2O3, and graphite substrates at 750 K and 10–6 Torr is studied. The effect of the substrate material on the rate of NH3 decomposition is established. It is demonstrated that the replacement of SiO2 by Al2O3 or graphite increases the decomposition rate 1.9- and 2.3-fold, respectively. The catalytic activity of the nanoparticles increases with the contact potential difference between the nanoparticles and the substrate. The potential difference between the nanoparticles particles and the SiO2, Al2O3 and graphite substrates are found to be–0.5,–0.2, and 0.0 V, respectively.

Adsorption of hydrogen on nickel nanoparticles with different crystallinity

The adsorption of hydrogen on nickel nanoparticles (NPs) deposited on the surface of highly oriented pyrolytic graphite by laser electrodispersion and by precipitation from colloidal dispersion has been studied by scanning tunneling microscopy and spectroscopy, as well as by Auger spectroscopy. The elemental composition of the NPs, structure, electronic structure, and interaction parameters with molecular hydrogen have been established.

Organoboron nanoparticles: synthesis, structures, and some physicochemical properties

Organoboron nanoparticles synthesized from carborane C2B10H12 by high-temperature pyrolysis of carborane vapor were investigated. The structures, electronic characteristics, and related physicochemical properties were found to depend on the sizes and shapes. The data of quantum chemical calculations performed in the framework of the density functional theory also indicate a relationship between sizes, dimensionalities, and electronic structure of the nanoparticles.

Interaction of hydrogen and oxygen with bimetallic nanostructured coating

The morphology of bimetallic coating formed in vacuum on the graphite surface at a high-temperature decomposition of HAuCl4 and Ni(NO3)2 has been found. The procedure of applying the precursors onto the substrate required for the formation of nanoparticles has been determined. The features of interaction of hydrogen and oxygen on the gold–nickel coating that we have formed are revealed.

Correlation between the catalytic activity of polyoxometallates and the special features of their tunnel and optical spectra

The tunnel spectra of phosphomolybdic acid, a classic heteropoly acid with a Keggin anion, were measured in ultrahigh-vacuum experiments with the use of scanning tunnel microscopy. The dependences of the resonance characteristics of the spectra, “negative differential resistances,” on the vacuum gap, material of contacts, and field polarity were studied. An earlier unknown mechanism of the formation of these characteristics was described. The mechanism included the action of strong electric fields in scanning tunnel microscope nanocontacts and a low degree of the delocalization of Keggin anion peripheral electrons. Strong electric fields (∼107 V/cm) characteristic of spectroscopic measurements with the use of scanning tunnel microscopes could break exchange bonds in heteropoly acids and their derivatives. This produced spectroscopic effects of interest for catalysis and nanoelectronics.