V. A. Kharitonov

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.

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.

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.

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.

Ammonia decomposition on a platinum nanocoating at various electric potentials

It was shown that the rate of ammonia decomposition on a platinum nanocoating can be controlled by applying an external electrostatic field to the coating to create a negative or positive platinum potential of variable magnitude. In experiments conducted with a contact time of 15 min between platinum and ammonia at a temperature of 700 K and a pressure of 5 × 10–7 Torr, the decomposition rate increased by 44% at a negative potential of the coating of–6 V and by 70% at a positive potential of +6 V.

Effect of the electric potential of organoboron nanoparticles on their catalytic activity in the decomposition of ammonia

For the first time, it has been shown that the rate of the catalytic decomposition of ammonia over (C2B10H4)n organoboron nanoparticles can be controlled via generating an electric potential of different polarity and magnitude on the particles using an external voltage source. At a temperature of 700 K, a pressure of 10–6 Torr, and a positive potential of the particles of +6 V, the decomposition rate increases by 26%, while at a negative potential of–6 V, it decreases by 37% compared to the decomposition rate of ammonia at a zero potential of the particles.

Catalytic hydrogenation of ethylene on organoboron nanoparticles formed by pyrolysis of C2B10H12 carborane

The ability of organoboron nanoparticles (C2B10H4)n to multiply enhance the yield of C2H6 in the hydrogenation of C2H4 at temperatures 770–970 K is experimentally demonstrated. The observed acceleration is of catalytic nature, since the electronic structure of the nanoparticles remains unchanged in the hydrogenation reaction.

Ethylene Hydrogenation on a Platinum Nanocoating at Various Electric Potentials

The possibility of controlling the rate of ethylene hydrogenation on a platinum nanocoating is established by applying to it electric potentials of different polarities and magnitudes from an external voltage source. At a negative potential of −10 V, the hydrogenation rate increases by 4%, whereas at a positive potential of +10 V, the hydrogenation rate increases by 42% under the conditions of the experiment at room temperature, atmospheric pressure, and an initial mixture composition of 0.09C2H4 + 0.91H2. Quantum-chemical calculations of the energy of the reaction of platinum hydride with hydrogen, Pt2H2 + H2 → Pt2H3 + H, and the energy characteristics of similar reactions involving negatively and positively charged Pt2H2 are performed. It has been demonstrated that the presence of a negative or positive charge on Pt2H2 lowers the endothermicity of formation of H radicals by 18.4 or 22.5 kcal/mol, respectively. Based on the calculation results, a mechanism is proposed to explain the effect of the charge of a platinum coating on its catalytic activity in ethylene hydrogenation.

The influence of electric charging on the catalytic ability of organoboron nanoparticles

The catalytic decomposition of ammonia on (C2B10H4)n composition organoboron nanoparticles deposited on the substrates of SiO2, Al2O3, and highly ordered pyrolytic graphite at T = 750 K and p = 1 × 10–6 Torr is investigated. It is found that the substrate material has a significant effect on the rate of decomposition of NH3. Replacing the SiO2 substrate by Al2O3 and graphite increases decomposition rate by 1.9 and 2.3 times. The possibility of controlling the speed of ammonia decomposition on organoboron nanoparticles by applying thereto an electric potential of different polarity and magnitude with an external voltage source is shown. The decomposition rate is increased by 26% at the positive potential of particles φ = +6 V and is reduced by 37% at the negative potential φ =–6 V compared to the ammonia decomposition rate at the ground potential of the particles.