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Quantum chemical calculations were performed on azacyclo C5 to C14 amines, open chain C6 to C14 amines and phenylazacyclo C5 to C14 amines. Inspection of the calculated parameters and corrosion inhibition efficiencies were made to observe any clear links, which might exist between the two. Possible correlations between experimental inhibition efficiencies and parameters such as dipole moment (μ), highest occupied (EHOMO) and lowest unoccupied (ELUMO) molecular orbitals and the differences between them, HOMO-LUMO gap (Δ), as well as some structural characteristics were investigated. The models of the inhibitors were optimized with the Modified Neglect of Diatomic Overlap (MNDO) method. The Quantitative Structure Activity Relationship (QSAR) approach has been used and a composite index of some quantum chemical parameters were constructed in order to characterize the inhibition performance of the tested molecules. The inhibition effect of polymethylene amines is closely related to orbital energies and/or energy gap and dipole moment. 相似文献
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Xiaowei Li 《Electrochimica acta》2008,53(22):6662-6667
Carbon-supported PdCo alloy electrocatalysts of different Pd/Co atomic ratios were simply prepared in an aqueous solution at room temperature with NH4F as a complexing agent and H3BO3 as a buffer, followed by NaBH4 reduction. As-prepared PdCo bimetallic nanoparticles show a single-phase face-centered-cubic (fcc) disordered structure, and the mean particle size is found to decrease with increase in Co content. TEM images demonstrated that the as-prepared PdCo alloy nanoparticles are well dispersed on the surface of the carbon support with a small particle size and a relatively narrow particle size distribution. For example, the average particle size of a Pd2Co1/C catalyst is ca. 3.0 nm, which is much smaller than that of the PdCo/C bimetallic nanoparticles reported by others. An activity evaluation of the oxygen reduction reaction (ORR) on as-prepared PdCo/C catalysts with a rotating disk electrode (RDE) technique indicated that the maximum ORR mass activity was observed for a Pd:Co atomic ratio of 4:1, but the highest specific activity was found on a Pd:Co atomic ratio of 2:1. Kinetic analysis reveals that the ORR on PdCo/C catalysts follows a four-electron process leading to water. Moreover, the PdCo/C catalyst exhibited much higher methanol tolerance during the ORR than the Pt/C catalyst, assessing that it may function as a methanol-tolerant cathode catalyst in a direct methanol fuel cell (DMFC). 相似文献