Chronoamperometry-based controllable fabrication of gold nanoparticle monolayers and their hydrophobic force-induced movement on indium tin oxide glass substrate

Owing to their unique plasmonic properties, noble metals have been the materials of choice for photovoltaics, photocatalysis and sensors. Here, we demonstrate novel gold(Au) monolayers with tailorable particle diameters and optical property on transparent indium tin oxide (ITO) using a simple electrochemical deposition. The nanoparticles on ITO are spherical and isolated, and are identified as Au0 nanoparticles. The gold nanoparticles are uniformly distributed on ITO surface, but the gold nanoparticle sizes increase and the particle population densities decrease at lower current densities, resulting in higher light scattering. There is a positive correlation between mean particle size and maximum extinction wavelength of gold nanoparticles prepared with different current densities under a fixed total charge, whereas the maximum extinction wavelength of gold nanoparticles does not change with the total charge under the fixed current densities. The localized surface plasmon resonance change of Au nanoparticles on ITO can be effectively tuned by regulating deposition current density. With the existence of alkanethiols on Au monolayers surface, the original pink color of gold monolayers changed to blue after immersion in toluene for 30 min, indicating hydrophobic force produced by oil-in-water (O/W) or water-in-oil (W/O) phenomenon caused gold nanoparticles to migrate and produce a color change.