Visible-light-absorbing mesoporous TiO2modified with tungstosilicicacid as photocatalyst in the photodegradation of 4-chloropheno

JULIÁN A. RENGIFO-HERRERA; ROMINA FRENZEL; MIRTA N. BLANCO; LUIS R. PIZZIO

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2014 vol. 289 p. 22 - 30

1010-6030

tVisible-light-absorbing materials based on TiO2modified with tungstosilicic acid (TSA; H4SiW12O40) wereprepared using titanium isopropoxide as precursor and urea as a low-cost pore-forming agent. X-raydiffraction (XRD) measurements show evidence about the presence of anatase TiO2in all samples andshifting of the anatase?rutile transition temperature toward temperatures higher than 600◦C. The FT-IRand FT-Raman studies showed that the main heteropolyoxometallate species present in the compositesannealed up to 500◦C is the [SiW12O40]4−anion, which exhibited a strong interaction with TiO2surfaceprobably due to the formation of TSA?TiO2complexes that should be responsible for its visible lightabsorption. The photocatalytic activity of these materials was tested using 4-chlorophenol as model pol-lutant. Results revealed that photocatalytic activity mainly depends on the TSA amount and the annealingtemperature. The amount of degraded 4-CP increased with the increment of TSA content, with the onecalcined at 600◦C being more active. Finally, it was found that these photocatalysts can be reused at leastthree times without an important decrease in the degradation and mineralization degrees.Visible-light-absorbing materials based on TiO2modified with tungstosilicic acid (TSA; H4SiW12O40) wereprepared using titanium isopropoxide as precursor and urea as a low-cost pore-forming agent. X-raydiffraction (XRD) measurements show evidence about the presence of anatase TiO2in all samples andshifting of the anatase?rutile transition temperature toward temperatures higher than 600◦C. The FT-IRand FT-Raman studies showed that the main heteropolyoxometallate species present in the compositesannealed up to 500◦C is the [SiW12O40]4−anion, which exhibited a strong interaction with TiO2surfaceprobably due to the formation of TSA?TiO2complexes that should be responsible for its visible lightabsorption. The photocatalytic activity of these materials was tested using 4-chlorophenol as model pol-lutant. Results revealed that photocatalytic activity mainly depends on the TSA amount and the annealingtemperature. The amount of degraded 4-CP increased with the increment of TSA content, with the onecalcined at 600◦C being more active. Finally, it was found that these photocatalysts can be reused at leastthree times without an important decrease in the degradation and mineralization degrees.