Controlled Synthesis of Gold Nanorods via Seeded Growth Approach

Abstract

AbstractThis work describes the synthesis of gold nanorods (AuNRs) produced using the seeded growth method. The properties of AuNRs with varying synthesis parameters such as amount of cetyltrimethylammonium bromide (CTAB), concentration of ascorbic acid, volume of seed solution and amount of HNO3 were studied. Sufficient CTAB amount is important in order to obtain AuNRs. Below 0.2 M CTAB, aspect ratio of AuNRs (length divide by width) was low because the AuNRs formed were short and thick. Insufficient CTAB amount could not form micelles that blocked the seed in a certain direction for growth of AuNRs. The aspect ratio of AuNRs increased up to 0.2 M CTAB, beyond which the spherical shaped Au nanoparticles were formed. The addition of ascorbic acid up to 0.08 M increased the aspect ratio of AuNRs. However, further increase in ascorbic acid concentration caused the aspect ratio to decrease due to fast reduction of Au ions. The aspect ratio of AuNRs rose with increasing the volume of seed solution of up to 50 μl, beyond which the aspect ratio decreased. The addition of HNO3 was beneficial to increase the aspect ratio of AuNRs up to 300 μl due to slower Au ions reduction. However, further addition of HNO3 formed shorter and unstable AuNRs colloids.KeywordsGold nanoparticlesGold nanorodsSeeded growthChemical synthesis