One-step synthesis of silver nanoparticles at the air–water interface using differentmethods

Abstract

Silver nanoparticles were synthesized in a one-step process at theair–AgNO3 aqueous solution interface under Langmuir monolayers of 5,10,15,20-tetra-4-oxy(2-stearicacid) phenyl porphyrin (TSPP) at room temperature by using different methods includingUV-light irradiation, ambient light irradiation, and formaldehyde gas reduction. It wasfound that parallel aligned one-dimensional (1D) chains composed of discrete silvernanoparticles with the size of 3–5 nm were formed under UV-light irradiation for a shorttime, while large areas of uniform silver spherical nanoparticles were formed undernatural daylight illumination for several days or by formaldehyde gas treatmentfor several hours. The average size of the spherical nanoparticles ranges from6.88 ± 0.46 to11.10 ± 1.47 nm, depending on the experimental conditions. The 1D chains formed underUV-light irradiation result from the templating effect of parallel aligned linearsupramolecular arrays formed by TSPP at the air–water interface, and rapidnucleation and growth of the nanoparticles. The formation of the uniform silvernanoparticles under daylight illumination or by formaldehyde gas treatment,however, should be ascribed to a kinetically controlled growth process of thenanoparticles.