Interfacial synthesis of noble metal nanoparticles

Palladium and gold metallic nanoparticles were generated two-dimensionally via the chemical decomposition of precursor molecules in a mixed Langmuir monolayer with arachidic acid (AA) or octadecyl amine (ODA) used as surfactants at the gas/aqueous borohydride solution interface in a gaseous phase of the monolayer (at low or no surface pressure). Water-insoluble Pd3(CH3COO)6 and Au(P(C6H5)3)Cl molecules were used as precursors. Surface pressure–monolayer area isotherms of control and particulate Langmuir monolayers were studied. It was found that the generation of nanoparticles can change the compression isotherm of the mixed monolayer and that synthesis of nanoparticles without surfactant also resulted in characteristic compression isotherm of the gas/sodium borohydride solution interface with floating nanoparticles. The morphology of synthesized nanoparticles was characterized by transmission electron microscopy (TEM). The size and shape of grown nanoparticles, and the structure of two-dimensional (2-D) aggregates and nanostructures, which resulted from the time-dependent self-organization processes, were dependent substantially on the monolayer composition and state during the growth process.