Comparison of the Photodesorption Activities of cis-Butene, trans-Butene and Isobutene on the Rutile TiO₂(110) Surface

Journal Article · Thu Oct 17 04:00:00 EDT 2013 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/jp408426y· OSTI ID:1114886

Henderson, Michael A. ^[1]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

The chemical and photochemical properties of three butene molecules (cis-butene, trans-butene and isobutene) were explored on the clean rutile TiO₂(110) surface using temperature programmed desorption (TPD) and photon simulated desorption (PSD). At the low coverage limit, trans-butene was the most strongly bound butene on the TiO₂(110) surface, desorbing at ~ 210 K, however increased intermolecular repulsions between trans-butene molecules at higher coverage diminished its binding. Both cis-butene and isobutene saturated the first layer on TiO₂(110) at a coverage of ~0.50 ML in a single TPD feature at 184 and 192 K, respectively. In contrast, the maximum coverage that trans-butene could achieve in its 210 K peak was ~1/3 ML, with higher coverages resulting a low temperature desorption at ~137 K. Coverages of these molecules above 0.50 ML resulted in population of second layer and multilayer states. The instability of trans-butene at a coverage of 0.5 ML on the surface was linked to the inversion center in its symmetry. In the absence of coadsorbed oxygen, the primary photochemical pathway of each butene molecule on TiO₂(110) was photodesorption. The photoactivities of these molecules on TiO₂(110) at an initial coverage of 0.50 ML followed the trend: isobutene > cis-butene > trans-butene. In contrast, the photoactivities of low coverages of cis-butene and trans-butene exceeded those measured at 0.50 ML. These data suggest that intermolecular interactions (repulsions) play a significant role in diminishing the photoactivities of weakly bound molecules on TiO₂ photocatalysts. Work reported here was supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences, and Biosciences, and performed in the Williams R. Wiley Environmental Molecular Science Laboratory (EMSL), a Department of Energy user facility funded by the Office of Biological and Environmental Research. Pacific Northwest National Laboratory is a multiprogram national laboratory operated for the U.S. Department of Energy by the Battelle Memorial Institute under contract DEAC05-76RL01830.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1114886
• Report Number(s): PNNL-SA--97705; 47406; KC0302010
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 45 Vol. 117; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Environmental Molecular Sciences Laboratory
cis-butene
isobutene
photon stimulated desorption
rutile TiO2(110)
surface photochemistry
temperature programmed desorption
trans-butene