Films of copper(I) oxide can be electrodeposited by reduction of copper(II) lactate in alkaline solution. Rietveld analysis of electrochemically grown films reveals pure copper(I) oxide with no copper(II) oxide or copper metal present in the films and a lattice parameter of a ) 0.4266 nm. The cathodic deposition current is limited by a Schottky-like barrier that forms between the Cu 2 O and the deposition solution. A barrier height of 0.6 eV was determined from the exponential dependence of the deposition current on the solution temperature. At a solution pH of 9 the orientation of the film is [100], while at a solution pH of 12 the orientation changes to [111]. Atomic force images of the [100] oriented films have crystals shaped as four-sided pyramids, while the [111] films have triangular crystals. The grain size for films grown at 65 °C ranges from 2 to 5 µm. A refractive index of 2.6 was measured from the transmission spectrum for wavelengths between 1350 and 2800 nm. The p-type semiconductor has a direct bandgap of 2.1 eV.

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Quantum confinement of carriers in nanometer-scale materials leads to size-dependent optical and electrical properties that are intermediate between those of molecules and those of extended network solids. The quest in this area of research is to engineer a normally intrinsic property such as a semiconductor bandgap by simply changing the siLe of the material. Semiconductors in this size regime can also show enhanced carrier mobility, nonlinear optical properties, and quantized charge transport. Examples of quantum-confined materials include superlattices,i',2J quantum dots,["'1 and surface-confined systems such as quantum corralsi7] Work on chemically produced nanometer-scale materials has mostly focused on toxic, heavy-metal chalcogenides such as CdS and CdSe.[3,5,61 Since it is difficult to make actual devices out of individual quantum dots, these materials have not been technologically exploited. Here we show that composite films of cop-

Nanocrystalline cerium oxide films with grain sizes as small as 6 nm are deposited by anodic deposition. Cyclic voltammetry studies of a series of complexing ligands indicate that formation constants below 1×103 and a solution pH between 7 and 10 are needed for CeO2 film formation. A mechanism is proposed for the deposition of polycrystalline CeO2 films by anodic deposition. © 2003 The Electrochemical Society. All rights reserved.

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Nanostructured CeO2 films are produced by anodic electrodeposition onto a variety of substrates. The crystal structure and oxidation state of the films are studied by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), respectively. Calculations from XRD show that crystallite sizes of the electrodeposited films range from 6–10 nm. Sintering of these films to 700 °C increases the grain size to approximately 25 nm. A study of Ce 3d, Ce 4d, O 1s, and the valence-band region indicates that the Ce(IV)/Ce(III) ratio increases with sintering temperature, with features of both Ce4+ and Ce3+ identified by XPS. Ce 3d and O 1s characteristics show that high-temperature sintering of the films facilitates Ce(IV) oxide formation.

Eastman-AQ55D is a new poly(ester sulfonic acid) cation exchanger available in a commercial dissolved form. Films of this polymer were coated onto glassy carbon surfaces, and the resulting electrodes exhibit attractive permselectivity, ion-exchange, and antifouling properties. Substantial improvement in the selectivity is observed as a result of excluding anionic species from the surface. The charge-selective behavior is demonstrated in the presence of a variety of compounds of neurological significance. A rapid response to dynamic changes in the concentration of cationic and neutral species is observed. The polymer strongly binds multiply charged counterions. Cyclic voltammetry is used to determine the quantity of incorporated ions as a function of time, concentration, and other variables. The oxidation of hydrogen peroxide is catalyzed when Ru(bpy)3(2+) is incorporated in the coating. The film can also protect the substrate electrode from foulants present in the contacting solution. These features, as well as the low cost, simple coating procedure, strong adherence to surfaces, and versatility, make the Eastman-AQ55D polymer well-suited for a variety of electro-analytical applications.

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