Date of Award
Doctor of Philosophy (PhD)
Materials Science & Engineering
Hydrogen has the potential to meet the growing demand for clean energy, but several major challenges still need to be addressed. Metal hydrolysis is an approach proposed to produce and utilize hydrogen and to store hydrogen in the form of solid metals and liquid water to address some of these challenges. However, few works focus on studying the reaction of nanostructured metals with deionized water because of the passivation layer that typically forms on metals when exposed to air or water during the metal hydrolysis process. Electrolytic dealloying can be used to prepare nanoporous aluminum metal with high surface areas for hydrolysis, but this method has drawbacks in experimental flexibility. Thus, the focus of this work is on investigating the underlying reactivity of nanoporous aluminum metal in its hydrolysis reaction with pure water and on investigating the additional challenges associated with both the nanoporous metals used for hydrolysis and the electrolytic dealloying synthesis method. First, addressing the challenges of hydrogen were explored. The hydrolysis of nanoporous aluminum at room temperature was explored to create activated alumina as a value-added product to lower the costs of hydrogen produced by this approach. Practical investigation in using nanoporous aluminum showed safety concerns regarding the high reactivity and pyrophoricity of the metal; creating a pellet form of nanoporous aluminum with hygroscopic lithium borohydride was shown to nullify pyrophoricity via accumulation of water vapor at the surface of the pellet and thus increase the air-stability of NP-Al for practical purposes. Finally, the electrolytic dealloying synthesis method to create nanoporous aluminum for hydrolysis was also investigated. Here we show changing the electrolyte was able to synthesis ultrafine nanoporous aluminum, which fundamentally changes the reactivity and possible applications for this material. Changing the parent alloy is also investigated to show isolation and synthesis of the Mg11Cu6Al12 phase, which is difficult to synthesize by regular thermal means. Thus, the capabilities of electrolytic dealloying are fundamentally enhanced from this investigation.
Lee, Timothy Eng, "Electrolytic Demagnesiation Of Magnesium Alloys Towards Nanoporous Aluminum And Intermediate Ternary Compounds For Hydrogen Generation And Beyond" (2022). Publicly Accessible Penn Dissertations. 4849.