Influence of <i>p</i>H<i> </i>and supporting electrolyte on electrochemical reduction of CO₂ using nickel(II) macrocyclic complex of 1, 3, 6, 9, 11, 14 - hexaazacyclohexadecane as catalyst at HMDE

472-477Electrochemical studies on the title compound using cyclic voltammogram (CV) and control potential electrolysis (CPE) techniques reveal that it reduces CO2 electrocatalytically at -1.36V /SCE at hanging mercury drop electrode (HMDE) in aqueous medium using LiClO4 as a supporting electrolyte. The products are found to be CO and H2 in 3:2 mole ratio in the gaseous phase as detected using gas chromatography (GC) and trace amounts of formic acid in solution phase as detected using colorimetric technique. The Ik / Id values (where Ik is the kinetic current measured in the presence of CO2 and Id is the diffusion current measured in N2 atmosphere) observed at various pH values show that pH 5.0 is best suited for CO2 reduction. In addition, the hydrophobicity/hydrophilicity near the electrode surface provided by the cation of the supporting salt and its influence on CO2 reduction is discussed

3₁₀ helix formation in protected tripeptide

The conformational analysis of a synthetic peptide Boc-Lys(Z)-Gly-Val-NHMe has been carried out, as a model for nucleating segment in helix formation. 1H NMR studies (270 MHz) suggested that the Gly (2) NH, Val (3) NH and NHMe groups are solvent shielded. Conformational energy calculations and intramolecular hydrogen bonding constrains favour 310 helix structure for the peptide. Theoretical and spectroscopic results are consistent with the presence of a transannular 4 -> 1 hydrogen bond between Lys (1) CO and NHMe with Gly (2) NH and Val (3) being sterically shielded from the solvent environment

Development of nanophase CeO2-Pt/C cathode catalyst for direct methanol fuel cell

Incorporation of nanophase ceria (CeO2) into the cathode catalyst Pt/C increased the local oxygen concentration in an air atmosphere, leading to enhanced single-cell performance of direct methanol fuel cell (DMFC). Ceria doped catalysts were effective at low oxygen partial pressure (≤0.6 atm) conditions and 1 wt.% CeO2 doped Pt/C exhibited the highest performance. The effect of ceria was more prominent with air as the cathode reactant and the ceria acted as a mere impurity in a pure oxygen atmosphere, decreasing the DMFC performance. Impedance spectra showed a decrease in polarization resistance with the ceria addition to the cathode catalyst in low-potential regions confirming the facile mass transfer of the reactant oxygen molecules to catalytic sites. Transmission electron microscopy (TEM) pictures showed a uniform distribution of CeO2 around platinum sites.Korean Federation of Science and Technology Societies (KOFST) and Korea Science and Engineering Federation (KOSEF) for support and assistance through Brain Pool Progra