Dissertation Seminar: Chen Wang will present his dissertation research “Anodic Metal Dissolution in Haloaluminate Molten Salts/Ionic Liquids” to the department.

The anodization of aluminum was investigated in the low-melting, mixed halide molten salt system, LiAlBr₄-NaAlCl₄-KAlCl₄ (30-50-20 m/o), and in the Lewis acidic chloroaluminate ionic liquid, aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl₃-EtMeImCl) using rotating disk electrode voltammetry. In both cases, at modest overpotentials, the anodization reaction proceeds under mixed kinetic/mass-transport control. However, at larger positive overpotentials and correspondingly higher anodization rates, the reaction transitions to a mass transport-limited process governed by the dissolution of a passive layer of AlCl₃(s) and/or AlBr₃(s) on the electrode surface. In AlCl₃-EtMeImCl, the passive current density scales linearly with the concentration of AlCl₄^– in the ionic liquid. The heterogeneous rate constant, referenced to the equilibrium potential, and the transfer coefficient of the Al anodization reaction were measured in the absence of passivation in both ionic solvents. The exchange current densities were independent of the composition of the AlCl₃-EtMeImCl ionic liquid, and the anodic transfer coefficients were close to zero in both cases. Surprisingly, the kinetic results were independent of the Al grain size.
The anodic dissolution of copper was also investigated in the AlCl₃-EtMeImCl ionic liquid. A kinetic analysis of the anodic dissolution of copper in the Lewis acidic and basic compositions of the AlCl₃-EtMeImCl ionic liquid was completed. In the Lewis acidic ionic liquid, the current density is potential-dependent and time-independent under all experimental conditions. That is, the anodization of copper proceeds under mixed kinetic/mass-transport control without complication from surface species, e.g., salt precipitates. However, in the Lewis basic ionic liquids, when the anodic dissolution rate is increased above a certain critical value, the current density becomes potential-independent. This behavior is due to the formation of a CuCl surface film, and the passive current density is governed by the dissolution of this species. At lower anodization rates, when the Cu reaction exhibits mixed control, modeling indicated that CuCl₂^– is the diffusion-limited species. The anodic transfer coefficient was close to 0.5.

Dr. Frank Fronczek (LSU) will present a seminar to the department.

Seminar: Graduate Student John Kelly will present his dissertation research to the department.

Seminar: Graduate Student Milan Rambukwella will present a seminar to the department.

Graduate Student Lizhu Chen will present “Robust Fe=O Catalysts for Water Oxidation” to the department.

Many environmental problems like global warming; ocean level rises and ocean acidification fused with our reliance on fossil fuels as an energy source. To avoid or mitigate the impact of fossil fuel consumption, new technologies for sustainable, carbon-neutral energy are needed. Water oxidation, a key step in natural and artificial photosynthesis, is responsible for supplying the protons and electrons needed in reductive half reactions that convert solar energy into chemical fuels. Developing inexpensive and efficient catalysts for this multi-electron/multi-proton process remains an important research objective.¹In this context, one site iron nuclear catalysts have been reported for water oxidation, and the mechanism based on noble metal catalysts studies has been well developed, but limited reactivity and poor catalyst stability are common among these systems.²

Reference

1) Kärkäs, M. D.; Verho, O.; Johnston, E. V.; Åkermark, B. Chem. Rev. 2014, 114, 11863.

2) Fillol. J. L; Codola. Z; Bosch. I. G; Gomez. L; Pla. J. J; Costas. M. Nature Chem. 2011, 3, 807.

Graduate Student Tanya Jones will present “Bulky-Thiolated Gold Nanomolecules: Synthesis, Characterization, and Crystal Structures” to the department.

Dr. Gregg Davidson (Ole Miss Department of Geology and Geological Engineering) will present “The Evolution of an Oxbow lake: Changes in Sediment Accumulation Inferred from 210Pb, 137Cs, and the 14C Activity of Bulk Sediment Fractions” to the department.

Graduate Student Yanbing Zhang will present “Near-Infrared Fluorescence Imaging Dyes in Living Systems” to the department.

Dr. Patrick Curtis (Ole Miss Biology) will present a seminar to the department.

Graduate Student Adithya Peddapuram will present “Anchoring Groups for Dye-Sensitized Solar Cells (DSCs)” to the department.