CO Adsorption Site Preference on Platinum: Charge Is the Essence
G. T.Kasun Kalhara Gunasooriya, Mark Saeys
文献索引：10.1021/acscatal.8b00214
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摘要
The adsorption of CO on transition-metal surfaces is a key step in catalysis and a reference system for surface science and computational catalysis. Here, the change in CO site preference with coverage, from top to bridge and back to top, is analyzed using charge transfer and chemical bonding. The relative stability of top and bridge sites is related to the variation in the surface platinum charge with CO coverage. Both the Pt–C σ* (Pauli repulsion) and the C–O π* (back-donation) occupancies increase with platinum charge; however, destabilizing Pauli repulsion dominates over stabilizing back-donation, and adsorption weakens with increasing surface charge. CO at the top sites is more sensitive to Pauli repulsion, leading to a change in site preference from top to bridge with increasing platinum charge and, consequently, with increasing CO coverage. The higher back-donation at the bridge sites eventually switches the site preference back to top near monolayer coverage.