Chemistry & Biochemistry Rebecca Gilchrist, PhD Thesis Defense: "Materials Development Toward a Sustainable Future and a Lowered Carbon Footprint: Molecular–Complex Interactions for Carbonate Formation and Metal Hydrides."

Chemistry  & Biochemistry Department

Presents

Rebecca Gilchrist PhD Defense

Materials Development Toward a Sustainable Future and a Lowered Carbon Footprint: Molecular–Complex Interactions for Carbonate Formation and Metal Hydrides.

Monday, April 27th 2026 10am in GP 1002

Human driven CO2 emissions are drastically rising and with that, the global temperature is on an upward trajectory with drastic climate implications. This thesis investigates two carbon remediation strategies targeting essential industries: construction and transportation. Combined, these sectors are responsible for over half the United States’ carbon emissions. The studies provide new insight on carbon negative cementitious materials and a deeper understanding of the hydrolysis of lithium aluminum hydride (LiAlH₄) for hydrogen storage applications. In the case of the construction sector, we utilize a molecular mimic of carbonic anhydrase, Zn(cyclen), to catalyze CO2 hydration in extreme alkaline environments to replicate activity in cementitious materials. At increased concentrations, Zn(cyclen) exhibits hydration rates comparable to the natural enzyme in extreme alkaline environments, with functionalization of Zn(cyclen) to better mimic carbonic anhydrase superstructure, unprecedented calcium carbonate conversion times are observed. These results demonstrate the feasibility of synthesizing improved catalysts for carbon sequestration within cementitious materials through development of molecular mimics that more accurately replicate the enzyme superstructure. Beyond the construction sector, the reactivity of LiAlH₄ was investigated using multiple in situ characterization techniques to deconvolve the reaction mechanism of the vapor mediated hydrolysis for hydrogen storage applications in the transportation sector. LiAlH₄ has high hydrogen storage capacities, however, has not been investigated for on-board storage applications. These studies reveal a two-step reaction mechanism – an immediate hydrogen release coupled with the formation of amorphous hydroxide intermediates ultimately resulting in a nearly complete loss of crystallinity, followed by a structural rearrangement to form a Li–Al layered double hydroxide. Collectively these discoveries provide mechanistic insight into catalytic CO₂ hydration in extreme alkaline environments and complex metal hydride reactivity, guiding the rational design of next-generation molecular catalysts and hydrogen storage materials.