Photocatalytic production of hydrogen from methanol offers tremendous promise for the generation of clean fuel for use in combustion and fuel cells. With the objective of gaining a more complete understanding of the mechanism and kinetics of methanol photocatalytic oxidation, we employ high-vacuum surface-sensitive infrared spectroscopy as a probe of molecular and electronic changes to the system during catalysis (J. Phys. Chem. C 2012, 116, 6623). The catalysts we have studied are a unique class of ultraporous TiO2 and TiO2-supported Au aerogels that feature a nanoscale solid network interpenetrated in three dimensions (3D) by mesopores and small macropores. The 3D networks significantly stabilize metallic Au particles against thermal migration, provide open pathways for mass transport to and from the active centers, and significantly increase the number of metal�semiconductor junctions where charge transport and surface chemistry may occur. The utility of IR spectroscopy in semiconductor photochemistry stems from its ability to simultaneously probe both the discrete vibrational transitions of surface adsorbates and the electronic population within or close to the continuum of the semiconductor conduction band (J .Phys. Chem. C 2012, 116, 4535). Our experiments show that the initial uptake of methanol at 3D TiO2 and Au�TiO2 aerogels is governed by dissociation to methoxy adsorbates within both systems and that UV irradiation of the porous solids efficiently oxidizes methoxy species to surface-bound formates. Further, we find that networked-entrained Au particles sensitize the oxide nanoarchitecture and activate it toward photochemistry that extends well into the visible range with photooxidation rates at 550-nm that nearly match those at the UV-irradiated TiO2 aerogel (J. Phys. Chem. C 2013, 117, 15035).

Photochemistry of methanol at 3D networked aerogels of TiO<sub>2</sub> and Au/TiO<sub>2</sub>

247th National Meeting (2014)

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Photochemistry of methanol at 3D networked aerogels of TiO2 and Au/TiO2

Photochemistry of methanol at 3D networked aerogels of TiO₂ and Au/TiO₂