Electrochemical functionalization at anodic conditions of multi-walled carbon nanotubes with chlorodiphenylphosphine

Covalent functionalization of multi-walled carbon nanotubes (MWCNTs) and oxidized MWCNTs (o-MWCNTs) with chlorodiphenylphosphine (Ph₂PCl) has been studied by cyclic voltammetry in organic medium. Depending the upper potential limit used in the electrochemical functionalization, different amount of phosphorus incorporation n is obtained, as result of the formation of radical species during the electrochemical oxidation of the Ph₂PCl. The electrochemical oxidation of Ph₂PCl promotes the covalent attachment of diphenylphosphine-like structure on the carbon nanotube surface. At the same time, the incorporation of Cl on the carbon nanotubes is observed during the functionalization. Furthermore, the presence of oxygen surface groups on the MWCNTs provides a favorable attachment of the Ph₂P^∙+ species, which has promoted preferentially the formation of C–P bonds, whereas the amount of Cl is reduced.