TEMPERATURE-PROGRAMMED DESORPTION MASS-SPECTROMETRIC STUDY OF THE SURFACE-PROPERTIES OF GLASSY-CARBON

The temperature-programmed desorption (TPD) method combined with mass spectrometric analysis has been applied to the characterization of gla ssy carbon (GC) and modified glassy carbon surfaces. Five different sa mples of GC were obtained from a commercial resol type of phenol forma ldehyde resin that bad undergone several treatments: the samples were either pure GC, GC treated with boron and phosphorus, or GC modified b y metal (silver and palladium). Mass spectrometric analysis has shown that the thermal decomposition of surface oxide species results in des orption of H2O, CO and CO2, these being the major gas products. On the basis of the TPD spectra obtained, desorption energies have been calc ulated using a peak position method. The influence of CO2 oxidation on the surface properties of the samples was also investigated. It was c oncluded that metal deposition on a glassy carbon surface contributes to increased stability of surface oxide species, the most stable surfa ce being one that has been modified by palladium deposition.