Adsorption properties of immobilized metal nanoparticles

The adsorption properties of the original TiO₂, MgO, and SiO₂ surfaces and those modified with nanoscale gold and nickel particles are studied using the dynamic sorption in a range of low coverages. N-alkanes (C₆–C₉) and adsorbate molecules with different donor and acceptor properties were taken as the reference compounds. Differential molar heats of adsorption of the adsorbates (Q _ν) are determined from the experimental retention data and, in the case of polar adsorbates, contributions from the dispersion and specific interactions to Q _ν are found. Donor and acceptor characteristics of the original and modified oxide surfaces are estimated. The immobilization of gold and nickel nanoparticles is shown to result in the formation of less active donor (K _D ) and acceptor (KA) sites compared to those on the original substrate surfaces. Changes in the surface chemistry and adsorption properties of Au/SiO₂ composites compared to the original substrate are less pronounced than in the case of Au,Ni/TiO₂ and Au,Ni/MgO composites.