Fabrication of gold/silica composite artificial opal by a multiple-step electroplating process

摘要

Artificial opal with a three-dimensional periodic structure was prepared using mono-dispersed silica microspheres by a force packing method in an Indium Tin Oxide (ITO) glass cell. The gold/silica composite opal was obtained through the infiltration of gold nano-particles into the voids of the silica opals by electroplating technique. The transmission and reflection spectrum of the gold/silica composite opal presented a red shift with increasing electroplating time. The optical images were taken after each treatment of electroplating-washing-drying circle, which were precisely selected at same area using an optical microscope. The SEM images show that the gold nano-particles could be directly deposited on the surface of silica spheres in the opaline structure after electroplating. We proposed that the effective refractive index of the composite opal was increased because of the infiltration of gold, which resulted in the spectra shifting to a longer wavelength. The gold/silica composite opal film could provide a simple way to tune the opal properties by controlling the ratio of gold in the silica opal.