Size control of Au@Cu2O octahedra for excellent photocatalytic performance

Abstract

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.