Capillary Gradient-Induced Self-Assembly of Periodic Au Spherical Nanoparticle Arrays on an Ultralarge Scale via a Bisolvent System at Air/Water Interface

A capillary gradient-induced self-assembly strategy is developed to successfully fabricate 2D periodic Au nanosphere arrays on a centimeter-sized scale through a bisolvent system at air/water interface. The bisolvent system used in this strategy consists of two steps. It first induces Au nanoparticles (NPs) floating on the water surface. Then, it compresses the sparse Au NPs into a densely close-packed array by creating an effective capillary gradient along the water surface. This study indicates that the effects of the capillary gradient depend on water solubility and vapor pressure of a compressing solvent. A compression mechanism of capillary gradient is reasonably proposed for such self-assembly of a densely packed monolayer on the water surface. This proposed self-assembly strategy has advantages of having a simple operation and being environment-friendly. The assembled Au NP arrays can provide an important and promising platform for major applications in biosensors and catalysis.