We have studied thin oxide films supported on metal single crystals in order to model fundamental phenomena in heterogeneous catalysis. These films are prone to electron transfer through the film by tunneling. Depending on the electron affinity of the adsorbate on the film surface and the response of the oxide film itself, electrons may be trapped on the adsorbate. We have demonstrated this, both for metals such as Au as well as molecules such as O2 (Angew. Chem. Int. Ed., 52 11385 (2013); Angew. Chem. Int. Ed.,50 11525 (2011)). This concept has recently been extended to the activation of CO2. While CO2 is a thermodynamically very stable molecule, the presence of electrons leads to a considerable destabilization to a point where the transfer of electrons is energetically favorable. Electron rich metal nanoparticles, which accumulated charge via electron tunneling from the metal substrate underneath the film, are therefore potential sites for CO2 activation. We have utilized this knowledge to study the transformation of CO2 into oxalate C2O42- species at Au nanoparticles as a function of the nanoparticles shape.

Thin film oxide systems for electron transfer control

251st National Meeting (2016)

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