Voitko K. Catalase-like properties of nanoporous and nanoscale carbon materials.

The influence of structural characteristics and surface chemistry of natural and synthetic nanoporous (activated carbon) and nanoscale (carbon nanotubes, graphene oxide) carbon materials on their catalytic (catalase-like) properties was investigated. Effect of changing external factors (H2O2 concentration, pH, temperature) on the catalytic ability of carbon materials in the hydrogen peroxide decomposition reaction has been analyzed. The laws of enzyme kinetics have been applied for describing and comparing catalytic activity of carbon materials with the activity of the enzyme catalase. The influence of diffusion and chemical components of the activated carbon on it's catalytic activity was quantitatively estimated. Using Thiele-Zeldovich and oscillation theories correlation analysis between reactivity, diffusion and structural characteristics of catalysts has been done, the effective diffusion coefficients of molecules of H2O2 were calculated. It was shown that diffusion is not a determining factor in the catalytic activity of carbon materials. For increasing of the samples activity their surface was modified by oxygen-and nitrogen-containing functional groups and the enzyme catalase. The structure of functional groups of carbon materials has been determined using XPS and TPD MS methods and quantitative elemental analysis. Correlation between the structure of carbon matrix, changing their surface chemistry and catalase-like properties was established and based on these correlation rows of samples activity were proposed. Experimentally proved that the modification of active carbon's surface by oxygen-containing groups reduces its catalytic ability, whereas activity of oxidized carbon nanotubes is increasing. Modification by nitrogen heteroatoms leads to increasing of the catalytic properties of activated carbon and carbon nanotubes. It has been proved that the removal of oxygen-containing functional groups and modifying by nitrogen heteroatoms leads to decreasing of graphene oxide catalytic properties. The regularities of the influence of the electronic structure of the carbon materials model nanoclusters (C43O3H16, C42H16 and C40N2H16) on their catalytic activity in the decomposition of hydrogen peroxide have been determined.