Electrochemical deposition, characterization, and shape control of copper oxides
Abstract
Crystals with different shapes consist of different atomic arrangements on the surface (e.g. surface termination, symmetry, interatomic distances) which directly affect a material's reactivity and stability. Therefore, the ability to systematically tune the shape of a material would be invaluable in adjusting its properties and elucidating shape-property relationships. The two main processes that determine a crystal's shape are habit formation and branching growth. This work demonstrates how these two processes can be methodically regulated in the electrocrystallization of Cu2O from aqueous solutions. Crystal habit can be regulated by introducing additives that preferentially adsorb onto specific crystallographic planes. The effect and efficiencies of various additives (e.g. sodium dodecyl sulfate, Cl -, NH4+) in stabilizing {100}, {111} and {110} surfaces of Cu2O crystals will be discussed. While crystal habit mainly depends on the composition of the plating solution, the degree of branching can be independently regulated by controlling the reaction rate or overpotential. Two different mechanisms of branching growth during Cu 2O deposition have been identified. One is diffusion limited branching that appears with high overpotential and the other is reduction limited branching that is stabilized when using a low overpotential. These two different mechanisms will be comparatively discussed. By combining the ability to control habit and branching growth with the flexibility of electrodeposition in controlling crystal growth, numerous novel crystal architectures have been assembled by rationally designing growth conditions and a growth chronology.
Degree
Ph.D.
Advisors
Choi, Purdue University.
Subject Area
Inorganic chemistry
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