Photocatalytic Synthesis of Au Nanoplates

Shape-controlled Au nanoparticles are synthesized in general by liquid-phase chemical reactions that require reducing and organic protective agents as well as an Au complex, via seed-mediated growth. In the present study, we report a one-step photocatalytic synthesis of Au nanoplates and their dispersion in aqueous solution without using any reducing or organic protecting agents, simply by irradiating a TiO2 substrate with ultraviolet (UV) light in an aqueous solution containing [AuCl4]−. Chemical species necessary for Au nanoplate formation, such as [AuCl2]−, should be generated through photocatalytic reactions, and Au nanoplates without a thick organic protective layer are grown in the solution phase. X-ray diffraction (XRD) measurements revealed that the obtained Au nanoplates are single crystals with (111) as the basal planes. Additionally, it was demonstrated that the nanoplates deposited on glass show sufficient electronic conductivity and that the nanoplates are metallic, and they can directly exchange electrons with each other.