Intercalation and coordination of copper(II)–2,2′-bipyridine complexes into graphite oxide

Copper-intercalated graphite oxides (GO) were prepared by adding complex solutions of cupric ions and 2,2′-bipyridine (L) ligands to exfoliated GO dispersion at pH = 7. High adsorption capacity (>140 mg Cu/g GO) was found for adsorption from equimolar solution of Cu2+ and L, while the excess of ligand results in progressively decreasing adsorbed amounts. Electron paramagnetic resonance spectra revealed two principal adsorption mechanisms: the CuL32+ complex undergoes ion exchange adsorption, while CuL2+ and CuL22+ bind to graphene oxide layers by coordination.