DFT Studies on Polyoxopalladates and Polyoxometalate-surface Composites: From Structure to Catalysis

Identificador:  TDX:2641

Handle: https://hdl.handle.net/20.500.11797/TDX2641

Autors:  Lang, Zhongling

Resum:
The following general conclusions can be drawn from this thesis • The capture of a Mq+ ion by a peripheral PdII-oxo shell involves the competition between the mother PdII and the guest metal ions, the main factors governing the formation of a particular MPd12 being the electrostatic-interaction between the cation and the surrounding oxo ligands and the dehydration ability of the cation in solution, in which the charge and size of the guest cation are critical. The following general conclusions can be drawn from this thesis: • The capture of a Mq+ ion by a peripheral PdII-oxo shell involves the competition between the mother PdII and the guest metal ion. The main factors governing the formation of a particular MPd12 are the electrostatic interaction between the cation and the surrounding oxo ligands and the dehydration ability of the cation in solution, in which the charge and size of the guest cation are critical. • The nature of the interaction for Pd-Ag and Ag-Ag-Ag in novel Ag4Pd13 and Ag5Pd15 compounds have been characterized with QTAIM method. • The Kabanos-type POM is proved to electron sufficient resources for completely Au(III)→Au(0) reduction. This process is highly favourable from thermodynamic perspectives. • We have established a robust strategy for the modelling of charged species adsorbed on surfaces. The incorporation of counterions in the computational models is crucial for accurately reproducing the electronic properties. The inclusion of solvent reduces the over stabilization of the anion-cation or anion-surface interactions, describing much better the adsorbed system. • The lacunary PW11 cluster does not preferentially adsorb on the gold surface via its more nucleophilic mono defect face but, rather, through less negatively charged terminal oxygen ligands, induced by the strong anion−cation interactions from the same and neighbouring units. • The WGSR mechanism is proposed to mainly involves the adsorbed carboxyl (COOH*) intermediate induced from CO and H2O adsorbed on the PMo12-Au(111) interface. The role of POMs is to serve as both electron and proton acceptors. • The interaction of the TiO2 surface with both the fully oxidized PW11Ti and its reduced partner exhibits a covalent nature. The presence of the reduced anion efficiently improves the weak absorption of TiO2 in the visible