Synthesis of highly photoactive TiO2 and Pt/TiO2 nanocatalysts for substrate-specific photocatalytic applications

Abstract

The relative activity of TiO2 photocatalysts depends to a large extent on the type of test substrate. With this in mind, phenol, formic acid, 2,4-dichlorophenoxyacetic acid (2,4-D) and methyl orange (MO) were selected as test substrates due to their different degradation mechanisms. In this work, the aim behind the synthesis and subsequent surface modification of the nanocatalysts was to obtain the most efficient material for removing these test substrates from water. A series of nanocatalysts with different average particle size, specific surface area and anatase phase content were synthesized by sol–gel method followed by calcinations at different annealing temperatures or hydrothermal treatment. Subsequently, platinization of certain samples was carried out using a photodeposition method. The most efficient catalyst for phenol photodegradation was found to be that with the largest average particle size as well as the highest anatase phase ratio. The photodeposition of platinum on this sample had detrimental effects on phenol photodegradation. The platinized sample and anatase TiO2 with the lowest average particle size were the most efficient catalysts for the removal of formic acid. Finally, the platinized material also showed the highest photoactivity in the removal of 2,4-D and in the methyl orange bleaching test.