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Gold, palladium and other noble metal nanoparticles and their assembled film has a wide range of applications in optical, electronic, magnetic, catalytic. In recent years, paid close attention to the preparation of noble metal nanoparticles and assembled in the two-phase gas - liquid, liquid - liquid interface, the endless variety of ways. Development interface assembly of the new method, the preparation of two-dimensional and three-dimensional noble metal nanoparticles function film, is of great significance. In this paper, the excess stannous reducing agent and as a protective agent, were prepared stable Au the sol and Pd sol, and get on the gas - liquid interface of Au, Pd nanoparticles self-assembled film, its film-forming mechanism effects of surface-enhanced Raman scattering effect and / or electro-catalytic activity of the assembled film. The main contents are as follows: an acidic medium, with an excess of stannous restore chloroauric acid, gold sol obtained with stannous (SnCl3-form) for the stability of the protecting agent, the sol can be stored in the absence of air for several months . However, under contact with air aging sol, gold nanoparticles assembled with the porous structure of ultra-thin films can be obtained in a short time at the air - liquid interface. Raman spectroscopy experiments show, the interface assembly process involving the oxygen in the air caused by the ligand exchange. I.e., oxidation of the oxygen in the air consumption of the surface of the solution layer divalent tin (Sn (II)), causing a gold nanoparticle on the surface layer of the solution occurs between the ligand SnCl3-, and Cl-substituted, Cl-substituted SnCl3-ligand , the sol surface layer of gold nanoparticles instability, spontaneously assembled monolayer on the gas - liquid interface. In addition, the combination of the density functional theory (DFT) calculations, explain the transformation mechanism of ligand. The gold nanoparticles assembled film showed the a good SERS effect and electrocatalytic activity. The assembled monolayer SERS substrate, measured pyridine, phenanthroline, nicotinamide SERS spectrum. Further, the assembled film electro-oxidation in an alkaline solution of ethanol, glucose, vitamin C, preferably catalytic activity. 3. Acidic medium, an excess of Sn (Ⅱ) reduction by heating the palladium chloride to obtain a stable palladium sol, continuous heating aging after a certain time, can be obtained in the gas - liquid interface Pd nanoparticles assembled film. Its mechanism may be involved in the proliferation and assembly of Pd nanoparticles under heating conditions to the gas - liquid interface. The Pd nanoparticles assembled into film modified glassy carbon electrode or bright Pd electrodes in alkaline conditions showed better electrocatalytic oxidation of ethanol and formic acid activity.
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