Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Tuesday 19th September 2017 from 8.00am to 4.00pm (BST).

During this time our website performance may be temporarily affected. If you have any questions please use the feedback button available under our menu button. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 26, 2015
Previous Article Next Article

Thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2 thin films

Author affiliations

Abstract

The catalytic and photo-catalytic activity of well-defined anatase TiO2 nanocrystals for the partial oxidation of methanol was investigated using temperature-programmed desorption (TPD) in ultra-high vacuum in order to determine how crystallite size and shape affect reactivity. The TiO2 films used in this study were prepared from well-defined TiO2 nanocrystals synthesized by colloidal methods. These nanocrystals had a truncated bi-pyramidal shape which exposes primarily (101) and to a lesser extent (001) surfaces and ranged in size from 10 to 25 nm. Two distinct regimes of reactivity were investigated, namely in the dark and under UV light illumination. In the dark, methanol adsorbed dissociatively on the (001) planes and only molecularly on the (101) surfaces. Dissociated methoxy groups on the (001) surfaces coupled to produce dimethyl ether, suggesting the presence of fourfold coordinate Ti cations. Under UV light illumination, the nanocrystals were additionally found to be active for the photo-catalytic oxidation of methanol to methyl formate. On the (101) surfaces, this reaction proceeded in a stepwise photocatalytic pathway involving dehydrogenation of methanol to form methoxy groups and then formaldehyde, followed by coupling of these latter two species to form methyl formate. The (001) surfaces were also found to be photo-catalytically active but surface methoxy groups could be produced thermally and the reaction proceeds only to formaldehyde in the absence of molecularly adsorbed methanol. The overall photocatalytic activity of the nanocrystals was also was found to increase with increasing crystallite size. The results of this study show that thin films of well-defined nanocrystals are excellent model systems that can be used to help bridge the materials gap between studies of single crystal surfaces and high surface area polycrystalline catalysts.

Graphical abstract: Thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2 thin films

Back to tab navigation

Supplementary files

Publication details

The article was received on 20 Apr 2015, accepted on 04 Jun 2015 and first published on 08 Jun 2015


Article type: Paper
DOI: 10.1039/C5CP02307F
Citation: Phys. Chem. Chem. Phys., 2015,17, 17190-17201
  •   Request permissions

    Thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2 thin films

    D. A. Bennett, M. Cargnello, T. R. Gordon, C. B. Murray and J. M. Vohs, Phys. Chem. Chem. Phys., 2015, 17, 17190
    DOI: 10.1039/C5CP02307F

Search articles by author

Spotlight

Advertisements