Electrochemical oxidation of PAN- and pitch-based carbon fibers and deposition of palladium on the obtained materials

The electrochemical oxidation of polyacrylonitrile (PAN)- and pitch-based carbon fibers and the deposition of palladium on the electro-oxidized materials are comparatively studied. Electrooxidation of both kinds of carbon fibers is achieved by application of alternate anodic and cathodic pulses. Through this procedure cation-exchangeable groups are created on the carbon support. Under the same oxidation conditions the quantity of the cation exchangeable groups on the pitch-based carbon fibers is double in comparison to the PAN-based ones; this fact is correlated with the axial cross section of the pitch-based fibers. After cation exchange of Pd2+ followed by its electrochemical reduction to Pd0, Pd-modified carbon-fiber systems with strong catalytic properties are obtained. The catalytic activity of these systems is studied in the electrooxidation of hydrazine and the hydrogenation of benzoyl chloride, and is proved to be much more pronounced in the case of the Pd-modified pitch-based fibers, in agreement with the distribution of the Pd particles on the corresponding carbon substrate.