Photocatalytic hydrogen production using TiO2–Pt aerogels

• Synthesis and characterization of TiO2–Pt aerogels.
• Materials of high specific surface up to 162 m2 g−1.
• Hydrogen production by photocatalytic ethanol reforming.
• Colloidal Pt nanoparticle formation and size control.
• Importance of the number of active catalytic sites.

TiO2–Pt aerogel composites have been synthesized by mixing sol–gel titania with Pt colloidal suspensions followed by supercritical drying. The highest specific surface achieved with these materials ranged between 550 and 600 m2 g−1 before annealing and stayed relatively high, i.e. 162 m2 g−1, after calcination. The concentration of Pt nanoparticles ranged between 0.3 and 1.0 wt.% while their size ranged between 5.75 and 6.5 nm. These composites were employed as photocatalysts for room-temperature photocatalytic reforming of ethanol and hydrogen production. The highest hydrogen production rate, 7.2 mmol H2 h−1 g−1, was obtained in the case of the smallest and most concentrated metal nanoparticles underlying the importance of the number of active sites on the TiO2–Pt composites. This rate of hydrogen production is relatively high and reflects the relatively high specific surface of the employed photocatalysts.

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