Yashan H. Synthesis and photochemical properties of bimetallic nanoparticles of noble metals in water medium and silica matrix

Various synthesis methods of bimetallic Ag-Au nanopartilces (BMNP) in colloidal state as well as in mesoporous sol-gel silica films with controlled chemical composition and morphology by means of photochemical and/or thermal reduction of appropriate ions have been developed. The main principals of synthesis determining the BMNP’ optical properties and morphology within colloidal solution and silica matrixes were defined: the order of the corresponding ions photoreduction, chemical nature of stabilizers, energy and time of UV-irradiation, treatment temperature of the silica films and powders, quantity and the way of the silica coatings in dip-coating process. High absorbability of silica to the metal NP’s was determined as the interaction of functional groups of stabilizer with OHsurface groups of silica as well as the localization of BMNP within silica pores. Increase of gold NP’s content in BMNP led to the shift of SPR band maximum. The alloy, coreshell and island-like structures of BMNP is obtained on the silica surfaces. The chemical bond between BMNP and silica matrix is proved with XPS measurements of silica films containing bimetallic alloy under action of negative bias. Non-linear properties of BMNP in colloids were measured under action of femptosecond pulse laser irradiation. High bactericide activity of BMNP/silica suspensions against E.colі were observed. The obtained BMNP-silica films demonstrated the photocatalytic activity in the process of antibiotic tetracycline destruction.