The role played by the metal - support (MSI) and metal - metal (MMI) interactions on two important processes in controlling the catalyst performance - nucleation and molecular adsorption - has been investigated using density functional theory (DFT), by means of B3LYP functional, combined with localized molecular orbital energy decomposition analysis (LMOEDA), and natural bond orbital (NBO) calculations, with aid of a Pd/γ-alumina (110D) model (Pd/AlOH). Our results indicate the occurrence of an electronic metal - support interaction (EMSI) which induces a most intense charge transfer in the Pd → γ-alumina backdonation direction, most expressive in Pd → Al, promoting an electronic redistribution within the units and attenuating the MMI. Nevertheless, the MSI/MMI synergistic effect seems to favor slightly the nucleation of a fifth palladium atom, leading to a distorted square pyramidal arrangement for Pd.
View Article and Find Full Text PDFThe formation of a polyelectrolyte complex through dimers of alginate and chitosan in the presence of sodium cations (SA/CS), and its interaction with the glyphosate herbicide, has been investigated at the DFT level (B3LYP/6‒311+G(d,p)). The lowest energy structure for SA/CS presents one Na cation coordinated to both dimers and formation of two H-bonds involving COO- and NH. The coordination energy of Na contributes with about 40% of the total complex stabilization energy.
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