Study Of Methanol Electro-oxidation In The Light Of Quantum Chemistry

The direct methanol fuel cell (DMFC) is a variant of the proton exchange membrane (PEM) fuel cell, which uses aqueous methanol directly without prior reforming and releases final products just CO2 and H2O, meeting human being's environmental friendly demand. DMFC is regarded as one of the most promising fuel cells, but the cost and poor catalysis of electrode materials in DMFC, together with other technical problems, block DMFC from commercialization. In recent years, intensified research focuses on intermediates to speculate methanol dehydrogenation step. To further and systemically investigate the methanol dehydrogenation model is the hard and hot point in electrochemistry research.In this paper the methods of ab-initio and density function theory (DFT)of quantum chemistry were used to study the mechanism of the electro-oxidation of methanol on electrodes of platinum; the adsorption of carbon monoxide (CO) on Pt(100),Pt(110),Pt(111) and the antipoisoning ability of bimetallic catalysts in the form of mixed atoms and mixed quantity.The dehydrogenation process of methanol was investigated. It covers optimization of the geometry structure of methanol and its intermediate fragments on Pt (111), calculation of Mulliken overlap population, and analysis of Atomic Net Charge of the optimized systems. The study concluded: The Pt-H bond formed by the H of methanol and the Pt catalyst accelerated the dehydrogenation as methanol molecules are close to Pt (111). The three H atoms of methyl are not dehydrogenation at the same time, but the H at the same side with hydroxyl dehydrates first, then the other two H atoms dehydrate simultaneously. Owing to the reconstruction of surface and relaxation, the COH deflects and the H atom points to the Pt surface, when it comes to a certain distance the H dehydrogenation and the CO adsorbed on the Pt surface with a bridge pattern.The absorption of CO on three low index surfaces of Pt (100), Pt (110) and Pt (111) was studied in the light of quantum chemistry. With CO molecule absorption on the surface of Pt, the bond of C-O is decreased, and then the CO molecule was activated. By the comparing the surface binding energy, the strenths of the bond between CO and Pt has the following sequence, Pt(111)> Pt(100)> Pt(110). The calculation of electrons number at atomic orbits showed that the CO poison to Pt resulted from the formation ofσ-πbond between CO and Pt atoms. The extent of poisoning decreases in...