Direct Visualization of a Gold Nanoparticle Electron Trapping Effect
AuthorsWilliams, Oscar Bentley Jerdmyr
KAUST DepartmentKAUST Solar Center (KSC)
Surface Science and Advanced Characterisation, SABIC-CRD at King Abdullah University for Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
Embargo End Date2023-01-05
Permanent link to this recordhttp://hdl.handle.net/10754/675023
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AbstractA new atomic-scale anisotropy in the photoreaction of surface carboxylates on rutile TiO<sub>2</sub>(110) induced by gold clusters is found. STM and DFT+U are used to study this phenomenon by monitoring the photoreaction of a prototype hole-scavenger molecule, benzoic acid, over stoichiometric (s) s-TiO<sub>2</sub>, Au<sub>9</sub>/s-TiO<sub>2</sub>, and reduced (r) Au<sub>9</sub>/r-TiO<sub>2</sub>. STM results show that benzoic acid adsorption displaces a large fraction of Au clusters from the terraces toward their edges. DFT calculations explain that Au<sub>9</sub> clusters on stoichiometric TiO<sub>2</sub> are distorted by benzoic acid adsorption. The influence of sub-monolayers of Au on the UV/visible photoreaction of benzoic acid was explored at room temperature, with adsorbate depletion taken as a measure of activity. The empty sites, observed upon photoexcitation, occurred in elongated chains (2 to 6 molecules long) in the [11̅0] and  directions. A roughly 3-fold higher depletion rate is observed in the  direction. This is linked to the anisotropic conduction of excited electrons along , with subsequent trapping by Au clusters leaving a higher concentration of holes and thus an increased decomposition rate. To our knowledge this is the first time that atomic-scale directionality of a chemical reaction is reported upon photoexcitation of the semiconductor.
CitationWilliams, O. B. J., Katsiev, K., Baek, B., Harrison, G., Thornton, G., & Idriss, H. (2022). Direct Visualization of a Gold Nanoparticle Electron Trapping Effect. Journal of the American Chemical Society. doi:10.1021/jacs.1c12197
SponsorsThis work was supported by the European Research Council Advanced Grant ENERGYSURF and EPSRC (U.K.) (EP/L015277/1).
PublisherAmerican Chemical Society (ACS)
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