Size control of Au@Cu2O octahedra for excellent photocatalytic performance

Due to its intrinsic structure and characteristics, small size and monodispersity, control of single-crystalline Cu2O polyhedra in aqueous media is a challenge, which is important to overcome to achieve enhanced photocatalytic activity. Here, we use heterogeneous nucleation, rather than homogeneous nucleation, of Cu2O with gold nanorods as seeds to realize subsequent uniform crystal growth. We obtained nearly monodisperse octahedral Au@Cu2O nanocrystals with single-crystalline shells, which are distinct from the pentagonal column-shaped structures previously described. Due to the fact that one Au@Cu2O holds only one Au nanorod, two formulas were deduced for convenient size control of the Cu2O shell. The formulas were calculated by adjusting the amount of Au rods that are relatively quantified. The formula also allows the size of the final product to be predicted when a given amount of gold seeds are employed. The experimental results agree well with the calculated data. The result of larger surface area and improved charge separation from core-shell interaction, made five samples of different sizes exhibit excellent photocatalytic activity toward MO degradation. The synthetic strategy reported here provides a clue to monodispersity and size control of core-shell nanocrystals, which is useful in developing new catalysts with better performance that are urgently needed in the fields of both science and technology.