Surface characteristics and modification of different carbon materials

Abstract

In this work, surface characteristics of different carbon materials were investigated. The materials under consideration were: activated carbon, carbon monolith, carbon felt and glassy carbon (powder, plate and broken plate). The surface functional groups of the studied carbon materials were determined by Boehms method and point of zero charge by mass titration. The specific surface area was studied by BET method with N-2 adsorption. As a specific test for surface activity, cementation of silver from aqueous solution of silver salts was used. The rate of silver deposition on the carbon materials was studied as a function of immersion time (AgNO3 concentration 75 mg/dm(3)), as well as a function of concentration of AgNO3 solution (25, 50, 75, 100, 125 mg/dm(3)) by atomic absorption spectrometry (AAS) to determine the concentration of Ag in the solution. The morphology of silver coatings was characterized by scanning electron microscopy (SEM) and structural characteristics by X-ray diffraction. The results obtained show that metallic silver deposits were formed at the surface of all examined samples. Oxygen complexes at the surface of glassy carbon samples were analysed by temperature programmed desorption (TPD) before and after silver deposition in order to establish the mechanism of silver deposition.