Normal reaction conditions synthesis of colloidal titanium, tin and zinc oxides nanoparticles with potenciallities in photocatalysis

Semiconductor oxides nanoparticles have attracted the interest of the scientific community in the last decades. These particles have been widely studied and applied in photovoltaic conversion [1] and different photocatalytic reactions [2,3]. Their potentialities are determined by its size and shape, that is why the synthesis process is a crucial step for particle properties and many methods have been published [4-7]. Due to the great importance of the synthesis process the searching for new, low cost, simple or accessible ways still as one of the main goals in nanoparticle research. In this contribution we report new simple synthesis methods of TiO2, SnO2 and ZnO nanoparticles in quantum confinement regime. We have avoided using titanium alkoxides due to their high hydrolysis speed and cost. The reactions take place using dimethylsulfoxide (DMSO) as solvent and different precursor salts (TiI4, SnCl4, 5H2O or ZnAc (Zinc Acetate)) depending on the case. A solution of NaOH is added to produce the reaction under magnetic stirring. Absorption and Raman spectrocopies, X-ray diffraction and transmission electron microscopy (TEM,) were applied for characterization of the nanoparticles. The photocatalytic behavior in 1,4 dichlorobenzene (DCB) and bis(4-nitrophenyl) phosphate (BNPP) degradation is discussed. Particles obtained are in 1-4 nm size range and the smallest size are produced when using Na3C6O7H5. The formed semiconductor nanoparticles present a 'blue' shift in band gap energy (Eg) respect macrocrystals. That is explained on the base of quantum confinement effect due to the small particle dimensions that are comparable with the respectively Borh's exciton radio. Preliminary results point to photocatalytic decomposition of the studied pollutants, but further studies are required for clear explanation of the observed effects. New experiments are subjected to continue this work. (Full text)