Preparation and characterization of polyoxometalate-modified carbon nanosheets

We report an original approach for the preparation of quasi two-dimensional graphite sheets by exfoliation of highly oriented pyrolytic graphite. Pieces of HOPG were sonicated for variable time in aqueous solutions of phosphomolybdic acid. This leads to a gradual cleavage of the HOPG along the basal plane. The driving force of the process is the free energy resulting from the well-known strong chemisorption of phosphomolybdate ions on carbon. The resulting carbon nanostructures exhibit certain properties of the adsorbed polyoxometalate-anions. They form colloidal suspensions due to the negative surface charge and can be immobilized on surfaces containing cationic groups.