Browsing by Author "McPherson, DJ"

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    Electrochemical energy storage on nanoporous copper sponge
    (Springer Nature, 2022-03-24) McPherson, DJ; Dowd, A; Arnold, MD; Gentle, A; Cortie, MB
    A proof-of-principle double-layer symmetrical supercapacitor with nanoporous copper/copper oxide electrodes and an aqueous electrolyte is investigated. The electrodes are manufactured by selective dissolution of Al from a eutectic composition of Cu17.5Al82.5 using 5 M NaOH. The ostensible (i.e., net external) capacitance of a symmetrical two-electrode cell with 0.1 M KNO3 electrolyte is assessed over a series of charge/discharge cycles and is about 2 F per gram of Cu in this simple prototype. Capacitance varies during a discharge cycle due evidently to the deeply buried surfaces and pseudocapacitive reactions contributing charge toward the end of a discharge cycle. In principle such a device should have very low ohmic losses due to its highly conductive backbone and would be suitable for applications requiring maximum energy efficiency over repeated cycling. The aqueous electrolyte ensures fire safety but this comes at the cost of lower energy content. © The Authors - Open Access under a Creative Commons Attribution 4.0 International License
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    Strategies to control the spectral properties of Au–Ni thin films
    (Elsevier, 2014-01-31) McPherson, DJ; Supansomboon, S; Zwan, B; Keast, VJ; Cortie, DL; Gentle, A; Dowd, A; Cortie, MB
    Gold and nickel have quite different dielectric functions. Here we use a combination of calculation and sample manufacture to assess two strategies by which thin films of these elements can be produced with a controlled range of far-field optical properties. In the first approach, control can be achieved by manipulating the density of states of metastable solid solutions, which in turn controls the dielectric function. In the second approach the optical properties of the films are controlled by varying the geometry of stacks fabricated from the constituent elements. We show that the two approaches can produce equivalent results so both are viable options in practice. Modeling is used to reveal how the structure controls the optical properties and to map out the possible color gamut. Predictions are tested with thin film samples fabricated by magnetron sputtering. © 2013, Elsevier B.V.