Preparation and Photocatalytic Properties of Nanosized La~(3+) and Co~(2+) Co-doped TiO_2 by Microemulsions

摘要

La~(3+) and Co~(2+) co-doped titania nanoparticles were prepared from reacting TiOSO_4, La(NO_3)_3 and Co(NO_3)_2 with NH_4OH in water/Triton X-100-hexanol/cyclohexane microemulsions. The structure, surface morphology and the specific surface area of the samples were characterized. The photocatalytic efficiency of as-prepared TiO_2 was tested by photodegrading methyl orange. The results showed that doping with La~(3+) and Co~(2+) could suppress the growth of TiO_2 grains and increase the specific surface area; When the calcination temperature increased from 300℃ to 900℃, the average crystallite size of the particles increased from 7.3nm to 35.6 nm and the specific surface area of the particles decreased rapidly from 205.5m~2/g to 41.2m~2/g. The synthesized amorphous particles were transformed into anatase phase at 300℃, and further into rutile phase at 900℃. UV-Vis diffuse reflectance spectrum revealed that La3+ and Co~(2+) co-doped TiO_2 absorbed UV light and visible light, while pure TiO_2 could only absorb UV light. In the experiments of photodegrading methyl orange, it was proved that La~(3+) and Co~(2+) co-doped TiO_2 had high photocatalytic activity under UV light and visible light, while pure TiO_2 showed photocatalytic activity just under UV light.