On the Elusive Link between Adsorbate's Binding Energy and Bond Strength: An Illustration from CO Adsorption on Metal-Doped Graphene

Autor: Marisol Alcántara Ortigoza, Sergey Stolbov, Nagendra Dhakal
Rok vydání: 2017
Předmět:
Zdroj: ChemistrySelect. 2:9479-9485
ISSN: 2365-6549
Popis: Adsorbates’ binding energy is often used as an indicator of the adsorbate-substrate bond strength. Although one can compute any binding energy, models to gauge bond-strength are developed to rationalize and anticipate it for the rational search for efficient catalysts. Unfortunately, bond-strength alone fails to predict trends in binding energy because, as hinted by models since the 1970s, the binding energy is the outcome of a complex response of the system to the created bond. Therefore further understanding the difference between binding energy and bond strength is essential to catalysts design. Indeed, the adsorbate-substrate bond formation perturbs, not only the geometry of the system, but also the substrate and adsorbate's electronic charge density. Both effects overall reduce the binding energy by an energy attached to such perturbations, the so-called perturbation energy. Here, with the example of carbon monoxide adsorption on metal-doped graphene, we show that such perturbation energy may exceed 1 eV and render an unusual situation: Namely, although the binding energy of CO to the Au-doped graphene indicates that binding does not happen, we find evidence of a strong bond between CO and such substrate. Thus, in this case, the large perturbation energy totally disrupts the equivalency between bond strength and binding energy. Here we propose a method to compute the perturbation energy that bypasses dealing with an excited electronic state of the system.
Databáze: OpenAIRE
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