Nanostructured copper oxides and phosphates from a new solid-state route

Nanostructured copper containing materials of CuO, Cu₃(PO₄)₃ and Cu₂P₂O₇ have been prepared by solid-state pyrolysis of molecular CuCl₂·NC₅H₄OH (I), CuCl₂·CNCH₂C₆H₄OH (II), oligomeric [Cu(PPh₃)Cl]₄ (III), N₃P₃[OC₆H₄CH₂CN·CuCl]₆[PF₆] (IV), N₃P₃[OC₆H₅]₅[OC₅H₄N·Cu][PF₆] (V), polymeric chitosan·(CuCl₂)_n (VI) and polystyrene-co-4-vinylpyridine PS-b-4-PVP·(CuCl₂) (VII) precursors. The products strongly depend on the precursor used. The pyrolytic products from phosphorus-containing precursors (III), (IV) and (V) are Cu phosphates or pyrophosphates, while non-phosphorous-containing precursors (VI) and (VII), result in mainly CuO. The use of chitosan as a solid-state template/stabilizer induces the formation of CuO and Cu₂O nanoparticles. Copper pyrophosphate (Cu₂P₂O₇) deposited on Si using (IV) as the precursor exhibits single-crystal dots of average diameter 100 nm and heights equivalent to twice the unit cell b-axis (1.5-1.7 nm) and an areal density of 5.1-7.7 Gigadots/in.². Cu₂P₂O₇ deposited from precursor (VI) exhibits unique labyrinthine high surface area deposits. The morphology of CuO deposited on Si from pyrolysis of (VI) depends on the polymer/Cu meta ratio. Magnetic measurements performed using SQUID on CuO nanoparticle networks suggest superparamagnetic behavior. The results give insights into compositional, shape and morphological control of the as-formed nanostructures through the structure of the precursors.