Study Of Catalyst For MEthanol Oxidation In The Light Of Quantum Chemistry

These days, some types of fuel cells approach commercial feasibility. Fuel cell technology is now becoming applicable for a large variety of technical areas. Direct methanol fuel cell (DMFC) is the most promising power generator for electric powered vehicles (EV). However, the expensive cost and poor catalysis of the Pt catalysts used in DMFC, together with other technical problems, block DMFC from commercialization. In the present study, we aimed to clarify the mechanism of the electro-oxidation of methanol on electrodes of platinum and platinum alloy using ab-initio and density function theory (DFT) of quantum chemistry. It has been studied as well that the influences of the surface structure and properties of catalyst on catalysis activity. The structure of chemisorptions of methanol on catalysts, followed with Mulliken overlap population and energy of the complexes has been performed. We obtain the mechanism of the electro-oxidation of methanol on platinum. Methanol shuck off atom H when adsorbed on platinum, a Pt-H bond formed synchronously. A specific adsorptive pattern occurs on specific platinum surface because of specific atomic arrangement and specific electronic structure of electrocatalyst surface, which leads to specific intermediates on platinum surface. Methanol dissociates to CO and H on platinum electrode, on which CO is strongly adsorbed and accordingly becomes a detrimental intermediate. Ru, Sn, Cr and Mo surface atoms appear to favor the formation of oxygen-containing species OHads ,which can oxidize off CO adsorbed on Pt. The calculations have shown that the adsorption of OHads on atomic Pt, Ru, Sn, Cr and Mo belongs to chemisorptions. OHads on Pt, Ru and Mo show obvious capability of oxidizing CO; while, the capability of OHads on Sn and Cr is highly depend on the potential of metal electrode .In other words, the oxidation contribution of species OHads on Sn and Cr only takes place at a relatively high potential.. In addition, it has been found that the extent of poisoning is different for low-index single-crystal platinum surface. Chemisorptions of CO on Pt forms σ-π bond .On Pt[111],the feedback of π electron is the most, so the poisoning is the most . The calculations and analyses shows the extent of poisoning decreases in the orderPt[110]>Pt[100]>>Pt[111].