Polyol synthesis and chemical conversion of Cu₂O nanospheres

Polyol synthesis route, which is a popular and effective way of synthesizing noble metal nanocrystals, has been employed for the fabrication of Cu₂O nanospheres. With this method, the particle size of the product can be readily tailored by tuning the concentration of Cu(NO₃)₂ and/or poly(vinyl pyrrolidone). It has been demonstrated that the main driving force of this reaction is the difference in redox potentials between ethylene xglycol (EG) and NO₃^-, and not that between those of EG and Cu²⁺. The resulting Cu₂O nanospheres were used as a solid precursor for generating hollow nanospheres of copper sulfide with different sulfiding degrees, as well as CuO, via suitable chemical conversions. The Kirkendall effect determined the final hollow structure. The results in this paper provide a good example of the broadening of the scope of application of polyol synthesis route and may supply a thinking clue for the synthesis of other oxide materials.