Effect of the TiO₂ Nanocrystal Dispersion Over SBA‐15 in the Photocatalytic H₂ Production Using Ethanol as Electron Donor

Abstract In this work, a series of TiO₂‐based photocatalysts supported on mesoporous silica SBA‐15, which are synthesized with different wt% (10, 20, 40, 60, and 80) of TiO_2, are studied. The catalysts are evaluated in gas‐phase H₂ photo‐production using ethanol as an electron donor, observing changes in the hydrogen evolution with the TiO₂ loading with an optimum charge of 20% w/w. In addition, the presence of Pt leads to a huge enhancement of the catalytic activity showing also a volcano plot behavior, the 20% w/w again being the best catalyst (895.9 µmol H₂ g_cat⁻¹). This system also exhibits a high stability without a decrease in the production after 15 h. By means of different characterization techniques, it is possible to determine the interaction among the active phase, the metallic nanoparticle, and the catalytic support. These studies indicate that the use of mesoporous silica SBA‐15 as a support increases the dispersion of the active phase, resulting in an increase in the evolution rate of H₂. However, the lowest percentages of TiO₂ give rise to amorphous TiO₂ particles with high amount of superficial defects increasing the e⁻‐h⁺ recombination rate and decreasing the H₂ production.