Influence of Ti source on the Ti-HMS photocatalyst synthesis used in a water splitting reaction

• Published in: Materials research bulletin Vol. 109; pp. 82 - 89
• Main Authors: Sanches, Sabrina Guimarães, Flores, Jhonny Huertas, Pais da Silva, Maria Isabel
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2019
• Subjects: P25; Ti organic source; Ti-HMS; Water splitting; Ti-HMS; Water splitting; P25; Ti organic source
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2018.09.021

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•Ti was introduced into the framework of HMS mesoporous silica.•The organic source with best performance was the Ti isopropoxide.•Hydrogen was produced by water splitting reaction.•The activity was due to isolated Ti-oxide species exposed at HMS surface walls.
Photocatalysts based on Ti-HMS were prepared using different Ti sources. Ti organic sources (isopropoxide, butoxide and ammonium oxalate) and TiO2 bulk (P25) were introduced during the synthesis of hexagonal mesoporous silica (HMS) and compared to the pure TiO2-P25 bulk in water splitting reaction using UV radiation. The Ti-HMS photocatalysts were characterized by N2 physisorption, thermogravimetry, X-ray diffraction, infrared spectroscopy, diffuse reflectance spectroscopy and transmission electron microscopy. All Ti-HMS samples presented higher H2 production than pure TiO2 bulk no supported. Ti-HMS samples prepared from Ti organic source showed to be more photoactive in water splitting reaction. Ti(VI) isopropoxide as Ti source showed the highest photoactivity because of higher concentration of isolated tetrahedrally coordinated Ti-oxide species spread at the surface walls of the silica channels. These photoactive sites were considered the main active sites in water splitting reaction. However, isolated octahedral coordinated Ti species showed also a role as active sites in water splitting.