Size-controlled TiO2 nanoparticles on porous hosts for enhanced photocatalytic hydrogen production

• Highly dispersed TiO2 nanoparticles of 6 nm were successfully synthesized on ZSM-5 and SBA-15 hosts via a sol–gel impregnation method.
• TEM analysis revealed that particle size of TiO2 was strongly dependent on titania precursor concentration.
• Both TiO2 particle size and the support architecture strongly affect the photocatalytic activity of TiO2/porous host nanocomposites.
• 10 wt% TiO2/ZSM-5 exhibited the highest photocatalytic activity with respect to H2 evolution and external quantum yield.

Nanocystalline TiO2 particles were successfully synthesized on porous hosts (SBA-15 and ZSM−15) via a sol–gel impregnation method. Resulting nanocomposites were characterized by XRD, TEM, BET surface analysis, Raman and UV–vis diffuse reflectance spectroscopy, and their photocatalytic activity for H2 production evaluated. XRD evidences the formation of anatase nanoparticles over both ZSM-5 and SBA-15 porous supports, with TEM highlighting a strong particle size dependence on titania precursor concentration. Photocatalytic activities of TiO2/ZSM-5 and TiO2/SBA-15 composites were significantly enhanced compared to pure TiO2, owing to the smaller TiO2 particle size and higher surface area of the former. TiO2 loadings over the porous supports and concomitant photocatalytic hydrogen production were optimized with respect to light absorption, available surface reaction sites and particle size. 10%TiO2/ZSM-5 and 20%TiO2/SBA-15 proved the most active photocatalysts, exhibiting extraordinary hydrogen evolution rates of 10,000 and 8800 μmol gTiO2−1 h−1 under full arc, associated with high external quantum efficiencies of 12.6% and 5.4% respectively under 365 nm irradiation.

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