DFT study of catalytic activity of an ultrathin TiO2(110) layer covering Au(112): O2 activation, CO oxidation, and replacing Au with Ag

•CO oxidation over a rutile(110) layer covering Au(112) has been examined by DFT.•O2 adsorbs and activates on pentacoordinate Ti due to electron transfer via oxide.•O2 adsorption weakens with increasing oxide thickness and O2 coverage.•Barriers to reaction with CO(g) are ~ 0.6 eV for ad-O2 and ad-O.•O2 is similarly activated on Au/rutile(110), rutile(110)/Au, and rutile(110)/Ag.

As a model of Au-titania core-shell catalysts, an ultrathin rutile TiO2(110) layer inversely supported on Au(112) has been examined by DFT. O2 adsorbs and activates on the pentacoordinate Ti site of rutile(110) as O2 π* orbitals accept electronic charge from the Au support via the oxide, as was found for Au/TiO2. O2 reacts with CO to yield CO2 and O, which then reacts with CO to yield CO2 (barrier ~ 0.6 eV). O2 adsorption weakens with increasing O2 coverage and oxide thickness. The reactivity of O2 changes negligibly even if we replace Au with Ag.

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