Synthesis of copper(II) oxide nanoparticles by anion-exchange resin precipitation and production of their stable hydrosols

Copper (II) oxide nanoparticles are promising materials for applications in catalysis, biomedicine and photovoltaics. It is also possible to use them for the preparation of nanocomposites and hybrid nanoparticles. This work presents a new method for the synthesis of CuO nanoparticles, which allows their one-step preparation without washing and heating. The proposed anion-exchange deposition method is simple, fast and easily reproducible under normal laboratory conditions. It is shown that anion-exchange precipitation of copper in the presence of the polysaccharide dextran-40 from copper chloride and sulphate solutions produces well crystallised hydroxychloride Cu2Cl(OH)3 and hydroxysulphate Cu4(SO4)(OH)6, respectively, and from copper nitrate a weakly crystallised Cu(OH)2 phase. In the absence of polysaccharide, copper oxide nanoparticles are formed irrespective of the nature of the anion of the parent salt. The obtained materials were used to obtain hydrosols with high aggregation and sedimentation stability over a wide pH range (from 5 to 11). These sols are stable for more than 3 months at a concentration of 2 g/l (the average hydrodynamic diameter of the particles is 245 nm; the average ζ-potential is -31.1 mV). Based on the study of the optical and electronic properties of the obtained hydrosols, it was found that they could be of interest for photocatalysis and application in optoelectronic devices.