Breaking Methanol

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Science  01 Oct 2010:
Vol. 330, Issue 6000, pp. 12
DOI: 10.1126/science.330.6000.12-a

Titanium dioxide (TiO2) is a highly abundant material, and as such has been heavily investigated for widespread use of its photocatalytic properties. One potential application of increasing importance is the direct use of sunlight to generate hydrogen from water, a reaction that proceeds more readily at TiO2 surfaces when some methanol is mixed in. In this context, Zhou et al. have explored the behavior of methanol monolayers and submonolayers on TiO2 under ultraviolet irradiation. Using both two-photon photoemission spectroscopy and scanning tunneling microscopy, the authors present evidence for photoinduced dissociation of the adsorbed methanol via H transfer from the CH3O-H bond to a bridge-bonded oxygen on the TiO2 surface. Accompanying density functional calculations support assignment of the photoemission signal to perturbation of Ti d-orbitals by virtue of the tetravalent metal ion's interaction with the CH3O radical co-product, which pushes the ion out of plane. The temporal profile of the emission was not mono-exponential, implicating heterogeneous kinetics.

Chem. Sci. 1, 10.1039/c0sc00316f (2010).

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