Morphological transition of gold nanostructures induced by continuous ultraviolet irradiation

Gold nanoparticles were synthesized through a continuous UV irradiation method using citric acid as a reducer and protective agent. After a period of continuous UV irradiation, the nanoparticles transformed into two-dimensional (2D) nanonetworks, porous nanoplates and compact nanoplates with hexagonal, triangular or truncated triangular pores through a self-assembly process which was dependent on the citric acid concentration. Selected area electron diffraction (SAED) patterns indicated that both the nanonetworks and the porous nanoplates were single crystalline. The influence of citric acid concentration and irradiation time on the morphological transition of Au nanostructures was investigated. The process of morphological transition was presumably discussed.