Titanyum dioksit üzerinde tutturulmuş rodyum(0) nanoparçacıkları: Amonyak boranın hidrolizinden hidrojen üretimi için sentezi ve karakterizasyonu

The activity of catalyst is directly related to its surface area, the reduction of particle size of the catalyst is a promising way to increase the catalytic activity. An efficient way of increasing catalytic activity is the usage of metal nanoclusters which are expected to be more active catalysts than the respective bulk metal counterparts, because a large percentage of atoms are on the surface of nanoclusters. This dissertation reports the preparation, characterization and investigation of the catalytic activity of rhodium(0) nanoparticles supported on the surface of titanium dioxide (Rh(0)@TiO2) were in situ generated from the reduction of rhodium(III) ions impregnated on nanotitania during the hydrolysis of ammonia borane. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques as ICP-OES, XRD, SEM-EDS, TEM, XPS and the N2 adsorption-desorption spectroscopy. Highly dispersed rhodium(0) nanoparticles of size in the range 1.3-3.8 nm were formed on the surface of titanium dioxide. Kinetics of the hydrogen generation from the hydrolysis of ammonia borane in the presence of rhodium(0) nanoclusters were investigated depending on catalyst concentration, substrate concentration and temperature. As a result, hydrogen generation rate was found to be first-order with respect to the catalyst concentration and zero-order regarding the substrate concentration. In addition rhodium(0) nanoparticles supported on nanotitania show high catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value up to 260 min-1 at room temperature. Moreover, the results of kinetic study on the hydrogen generation from the hydrolysis of ammonia borane were also reported including the activation energy of 65.5 ± 2 kJ/mol for this reaction.