Light-induced reshaping of gold nanorods supported by graphene oxide

The reshaping of gold nanorods (AuNR) adsorbed onto graphene oxide (GO) and free-standing AuNR while they are irradiated by high intensity light is investigated in order to understand the transformational behaviors of hybrid materials. AuNRs are synthesized using the seed-mediated method and their characteristic surface plasmon resonance (SPR) bands are identified via UV-Vis spectroscopy. Aqueous solution of AuNRs are prepared following the procedure that has been used to successfully synthesize AuNR by others. However, the difficulty regarding the reproducible synthesis of AuNR using the seed mediated method initially hampered with the progress of this study. With a careful examination and some modification to the initial procedure, AuNRs with expected optical properties are obtained. AuNRs are then imaged by atomic force microscopy (AFM) to characterize their size and shape. Afterwards, the characterized AuNRs are irradiated by a solar simulator under the exposure of 1∼sun for 16∼min of time to investigate the reshaping behavior of AuNR. AFM scans located a few AuNRs on the Si substrate, but mostly gold nanoparticles (AuNPs) were found. AFM images of the AuNR-GO sample show that AuNRs can be located and they tend to become spherical AuNPs after light irradiation. Further extensive studies will be necessary to check the validity of these results and acquire more data concerning the rate of reshaping and effect of light intensity and exposure time to AuNRs.