Size and shape-tuned overgrowth on Au nanorods regulated by polyallylamine

Au nanorods prepared by a photochemical method were used as seeds for the overgrowth of thin shell of gold by using a mild reducing agent, ascorbic acid at ambient conditions. The overgrowth rate along different crystal facets of the starting gold nanorods was regulated by the addition of polyallylamine. The shape of the resulting gold nanorods was different from the naturally overgrown Au nanorods without any additives.