Functional Nanoporous Metals Fabricated through Electrochemical Dealloying


Student thesis: Doctoral Thesis

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  • Jie ZHANG


Awarding Institution
Award date3 Feb 2016


Dealloying, as an ancient technology for generating nanoporous metals by selectively etching away the more reactive metal component from an alloy system, is widely applied to fabricate various kinds of nanoporous metals. Major obstacles are present for the current dealloying techniques, such as, difficulty in controlling the dealloyed morphology/composition, slow dealloying rate, mechanical weakness of the dealloyed metals, and self-coarsening effect. These obstacles largely limit the practical applications of dealloyed nanoporous metals.
The first chapter provides a general introduction to electrochemically dealloying, severe plastic deformation and applications of dealloyed porous metals. The second chapter describes a novel study on dealloying Ni-Cu alloys using pulsed voltage waveforms. It is found that dealloying with pulsed voltage waveforms can significantly lower the compositional threshold of the more reactive metal component for the dealloying reaction to take place, remove the more reactive metal component more thoroughly, and better control the morphology/composition of the generated porous metal framework. The third chapter further demonstrates a pioneer work combining mechanical pretreatment—Surface Mechanical Attrition Treatment (SMAT) with dealloying for mass producing bulk porous metallic framework with finer nanostructures, accelerated dealloying kinetics, improved hardness and refrained self-coarsening effect. Monolithic supercapacitor electrodes enabled by SMAT-facilitated dealloying show a remarkable ultrahigh areal specific capacitance of 11 F/cm2 (at current density of 6 mA/cm2), and an ultrahigh energy density of 0.021 Wh/cm3 and power density of 0.80 W/cm3. The forth chapter describes another method of introducing plastic deformation to the parent alloy by cold rolling in order to tune the dealloying behaviors. The fifth chapter summarizes the findings of this thesis.