Formation of Gold Nanoplates on Indium Tin Oxide Surface:  Two-Dimensional Crystal Growth from Gold Nanoseed Particles in the Presence of Poly(vinylpyrrolidone)

The crystal growth of a two-dimensional plate structure of Au that covers the indium tin oxide (ITO) surface has been realized for the first time through liquid-phase reduction from Au nanoseed particles attached to the ITO surface in the presence of poly(vinylpyrrolidone) (PVP). By control of the concentration of PVP in the growth process, the formation of Au nanoplates was possible with surface coverage as high as 30%, although various shaped Au nanocrystals were concurrently formed on ITO. The Au nanoplates were single crystalline in nature with the (111) basal plane and the edge length of up to ca. ∼2 μm, growing parallel to the surface of ITO. The concentration of PVP in the growth solution was a key factor for the formation of Au nanoplates, because at higher or lower concentrations of PVP the purely spherical or irregular-shaped nanoparticles were formed. The absorption spectra implied anisotropic and specific optical characteristics of the Au nanoplate-attached ITO.