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A large electrochemical isotopic effect is observed upon the electrodeposition of lithium from solutions of propylene carbonate producing isotopically light metal deposits. The magnitude of fractionation is controlled by the applied overpotential and is largest close to equilibrium. Calculated partition function ratios for tetrahedrally coordinated lithium complexes and metallic lithium predict an equilibrium fractionation close to that measured experimentally.

The application of inverse opal structured materials is extended to the ceria-zirconia (Ce 0.5 Zr 0.5 O 2 ) system and the significance of material architecture on heterogeneous catalysis, specifically, chemical oxidation, is examined.Inverse opal structures have been explored and, in some instances, perfected as photonic crystals by the optoelectronics community. 1-4Materials ranging from carbon to transition metal oxides have all been fabricated as macroporous structures with ordered pores.5-7 In photonic applications, regular arrangement of the pore structure, with pore sizes generally in the visible wavelength range, is essential for achieving optical band gap characteristics. Inverse opals also display several characteristics that render them ideal for chemical and electrochemical catalysis including low tortuosity (particularly as compared to typical microporous materials 8 or to aerogels 9 ), high porosity, and stability against high-temperature coarsening. Furthermore, the requirements for structural perfection are much less stringent than those of photonic applications, although a high degree of structural perfection ultimately lends itself to quantitative modeling of catalytic behavior to a degree not possible with conventional catalyst support structures. Despite these attributes, only a limited number of studies have been directed towards the development of inverse opals for catalysis, 10-12 and any influence of the material architecture has yet to be demonstrated.Here, we report a robust method for preparing ceria-zirconia (Ce 0.5 Zr 0.5 O 2 ) inverse opals and provide preliminary catalytic results on the role of engineered macroscale porosity on catalytic activity. The synthesis of the end-member ceria as an inverse opal has been recently demonstrated, 13 however, the catalytic properties of that material were not examined. Ceria-zirconia, which combines the benefits of the catalytic activity 14 and oxygen storage capacity offered by ceria 15 and the structural stability offered by zirconia 16 was selected for this study because of its inherent importance in three-way catalysts for the destruction of toxic gases such as SO x and NO x , 17,18 as a support in ethanol reforming catalysts for hydrogen production, 19and as an anode material in solid oxide fuel cells, 20 amongst many other applications. Furthermore, given the intermediate stoichiometry, the synthesis methodology lends itself to compositional tuning throughout the CeO 2 -ZrO 2 system, as has already been demonstrated in the mesoporous analog. 8 We have utilized here a synthesis protocol (described in complete detail in the ESI †) by which a nanoparticulate sol is produced by reaction of zirconyl chloride and cerium ammonium nitrate.21 Equal molar ratios are dissolved in deionized water and the products of the reaction are allowed to evaporate from the solution. The resulting precipitate, composed of 3-5 nm oxide particles, is resuspended in deionized water. The particles are then infiltrated into the interstices of a closedpacked array of...