Peculiarities of Structure and Morphology of Copper-Cerium Nanopowders Produced by Laser Ablation

Abstract

Copper-cerium nanopowders CuOx–CeO2 (mass ratio Cu:Ce = 6:100) are prepared by mixing the dispersions of the copper and cerium oxides produced by the method of pulse laser ablation (PLA) in liquid, followed by drying. The initial dispersions of copper oxides were prepared by the method of PLA of a metal copper target in distilled water or 1% hydrogen peroxide solution, and those of cerium oxide – by PLA of metal cerium in distilled water. It is shown that ablation of copper in water and water solution of peroxide is followed by the formation of copper oxide particles of different morphologies and compositions (structure). It is established that no crystal phases of copper oxides are formed in the copper-cerium nanopowders produced from separate dispersions. Given this approach to forming copper-cerium nanoparticles, the oxidized copper is distributed in the form of a thin layer on the CeO2 surface, which is demonstrated by the results of investigation of these particles by the methods of high-resolution transmission electron microscopy and X-ray diffraction. The formation of a Cu–O–Ce interface at the interphase boundary gives rise to the formation of defects on the CeO2 surface, which is confirmed by the Raman spectroscopy. An investigation of the composition and electronic structure of the surface of CuOx nanoparticles and CuOx–CeO2 nanopowders performed by the method of X-ray photoelectronic spectroscopy reveals the presence of copper in the form of a combination of Cu (I) and Cu (II) with the prevailing contribution from a single-valence state for CuOx–CeO2 nanopowders, which could have resulted from the interaction between CuOx and CeO2 particles.