Photocatalytic Synthesis\nof Au Nanoplates

Shape-controlled Au nanoparticles are synthesized in\ngeneral by\nliquid-phase chemical reactions that require reducing and organic\nprotective agents as well as an Au complex, via seed-mediated growth.\nIn the present study, we report a one-step photocatalytic synthesis\nof Au nanoplates and their dispersion in aqueous solution without\nusing any reducing or organic protecting agents, simply by irradiating\na TiO<sub>2</sub> substrate with ultraviolet (UV) light in an aqueous\nsolution containing [AuCl<sub>4</sub>]<sup>−</sup>. Chemical\nspecies necessary for Au nanoplate formation, such as [AuCl<sub>2</sub>]<sup>−</sup>, should be generated through photocatalytic\nreactions, and Au nanoplates without a thick organic protective layer\nare grown in the solution phase. X-ray diffraction (XRD) measurements\nrevealed that the obtained Au nanoplates are single crystals with\n(111) as the basal planes. Additionally, it was demonstrated that\nthe nanoplates deposited on glass show sufficient electronic conductivity\nand that the nanoplates are metallic, and they can directly exchange\nelectrons with each other.