Synthesis and photocatalytic activity of silane-coated and UV-modified nanoscale zinc oxide

Abstract

A new nanoporous material consisting of nano-ZnO particles bridged by –O–Si–O–Si–O– units has been synthesized and characterized. The two-step synthesis involves a precipitation of zinc oxide from a 1 mol l−1 methanolic zinc acetate solution with methanolic KOH in the presence of alkoxyalkylsilanes as coating agents and a UV irradiation of the obtained material in aqueous suspension with air supply. This procedure leads to a nanoscale ZnO network with a high surface area (130 m2 g−1), a better chemical stability than other types of ZnO and a remarkable photocatalytic activity. The photocatalytic mineralization of tetrachloroethylene occurs in the presence of this material at pH = 8 even faster than with the well known and most appreciated nano-TiO2 (anatase).

ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation of Staphylococcus epidermidis biofilms

“…The antibacterial properties of ZnO in powder or nanoparticle forms have also been studied [18][19][20][21][22] and can be further enhanced by ultraviolet light activation [23]. Nanostructured ZnO has interesting properties towards the photocatalytic decomposition of organic pollutants [24] and dyes [25], while La-doped and silane-coated ZnO nanoparticles have recently shown remarkable photocatalytic action against monocrotophos [26] and tetrachloroethylene [27], respectively. Several studies have compared the effectiveness of the photocatalytic properties of ZnO for the inactivation of several pathogens with that of various metallic oxides and demonstrated that ZnO is highly effective in this context [23,28,29].…”

“…We have already mentioned that the hole diffusion length in ZnO is in the range 0.5-2 µm, thus it is reasonable to assume that some photogenerated holes will be driven towards the surface and reach the ZnO/biofilm interface. The photo-holes can then directly oxidize the bacterial organic matter [26,27]. Alternatively, they can oxidize water to produce hydroxyl OH…”

CuO/ZnO Nanoparticles in a Matrix of Amorphous Silica as High‐Surface Precursors for Methanol Synthesis

“…[30] The coating with silane prevented crystal growth and agglomeration of the primary oxides. The subsequent photochemical treatment almost completely destroyed the organic fragments of the silane and led to the formation of X-ray amorphous silica ("SiO 2 ").…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) prepare nanoscale ZnO. [30] By precipitating the oxides in the presence of a silane in alcohol, a highly dispersed mixture of the oxides with a high specific surface area [31] is obtained because the silane prevents the growth and agglomeration of the oxide crystals. [32] Subsequently, the organic substituents of the silane are photochemically oxidized and almost completely removed.…”

“…[32] Subsequently, the organic substituents of the silane are photochemically oxidized and almost completely removed. [30] The ratio of copper to zinc can be easily varied by this method, opening a way to nanocrystalline systems of CuO/ZnO in amorphous silica with a high overall specific surface area. Copper oxide can then be reduced to Cu, resulting in Cu/ZnO/SiO 2 , i.e.…”