Novel (NH4)4[NiMo6O24H6]·5H2O ? TiO2 composite system: Photooxidation of toluene under UV and sunlight-type illumination

MARIO J. MUÑOZ-BATISTA; GUILLERMO BERTOLINI

APPLIED CATALYSIS B-ENVIRONMENTAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 238 p. 381 - 392

0926-3373

A series of composite materials based on titania and growing quantities of the (NH4)4[NiMo6O24H6]·5H2Oheteropolyacid (NiMo6 HPA) was tested in the gas-phase toluene photo-oxidation reaction. Materials werecharacterized with the help of chemical analysis, X-ray diffraction, porosimetry, electron transmission andscanning microscopies, as well as X-ray photoelectron and UV?visible diffuse-reflectance spectroscopies. Photoactivityperformance was assessed under UV and sunlight-type illumination conditions through the calculation ofthe true quantum efficiency to measure activity as well as the analysis of the selectivity of the reaction. Thecomposite system having a 3 wt. % of the NiMo6 component presents improved performance with respect to welldefined titania references (parent nanosized anatase or P25) under all illumination conditions tested. Thecharacterization of the solids indicates that the NiMo6 component supported on titania suffers a significantmodification of its physico-chemical properties as a function of the loading of the composite system. Suchmodification appears as a consequence of the interface interaction between the components of the compositesystem. An electron paramagnetic resonance study of the radical species formed under illumination shows thatcharge handling through the NiMo6 ? TiO2 interface controls the photo-catalytic properties.