Controlled reactions on a copper surface: Synthesis and characterization of nanostructured copper compound films

We report the synthesis of nanostructured copper compound films on a copper surface under mild conditions. A series of low-dimensional structures including Cu(OH)(2) fibers and scrolls, CuO sheets and whiskers, and Cu-2 (OH)(2-)CO3 rods have been successfully grown on the copper surfaces at ambient temperature and pressure. Most of the structures are phase-pure single crystallites. The films were formed by the direct oxidation of copper in aqueous solutions of NaOH with an oxidant (NH4)(2)S2O8. The evolution of the ultrafine structures as a function of the reaction conditions has been revealed, from fibers of Cu(OH)(2) to scrolls of Cu(OH)(2) to sheets or whiskers of CuO. By replacing NaOH with NaHCO3 in the synthesis, square/rectangular rod arrays of Cu-2(OH)(2)CO3 were obtained. The controlled reactions allow the large-scale, template-free, cost-effective synthesis of copper compound films with ordered, uniform, stable, ultrafine structures.