Synthesis of Au nanorods via autocatalytic growth of Au seeds formed by sonochemical reduction of Au(I): Relation between formation rate and characteristic of Au nanorods

• Published in: Ultrasonics sonochemistry 2020-12, Vol.69, p.105229-105229, Article 105229
• Main Authors: Okitsu, Kenji, Semboshi, Satoshi
• Format: Article
• Language: English
• Subjects: Au nanorod; Au seed; Autocatalytic growth; Autocatalytic reduction; Sonochemical reduction
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2020.105229

•Yield, size, and shape of Au nanorods were evaluated by UV–vis and TEM analysis.•Characteristics of Au nanorods depended on ultrasonic irradiation condition.•Relation between formation rate and characteristic of Au nanorod was discussed.•Concentration balance between HAuCl4 and AA affected the reduction rate of Au(I).•Au nanorod became dog-bone shape and the size became small at high AA concentration. The sonochemical formation of Au seeds and their autocatalytic growth to Au nanorods were investigated in a one-pot as a function of concentration of HAuCl4, AgNO3, and ascorbic acid (AA). The effects of ultrasonic power and irradiation time were also investigated. In addition, the formation rate of Au nanorods was analyzed by monitoring the extinction at 400 nm by UV–Vis spectroscopy and compared with the growth behavior of Au seeds to nanorods. Most of the reaction conditions affected the yield, size, and shape of Au nanorods formed. It was confirmed that the concentration balance between HAuCl4 and AA was important to proceed the formation of Au seeds and nanorods effectively. The formation rate became faster with increasing AA concentration and dog-bone shaped nanorods were formed at high AA concentration. It was also confirmed a unique phenomenon that the shape of Au nanorods changed even after the completion of the reduction of Au(I) in the case of short-time ultrasonic irradiation for Au seed formation.