Activity and Stability Design Principles of Transition Metal Compounds for Decarbonization
Name
peng-jypeng-phd-dmse-2022-thesis.pdf
Description
Thesis PDF
Size
40.15 MB
Format
Adobe PDF
Checksum (MD5)
e34b2df9c55c58c3d07aa53034fd5b9b
Author(s)
Peng, Jiayu
Advisor(s)
Shao-Horn, Yang
Date Issued
May 2022
Publisher
Massachusetts Institute of Technology
Abstract
Enabling sustainability while mitigating the ever-increasing carbon dioxide emissions is one of the most significant challenges of our time. A key element in achieving these goals lies in developing renewable energy technologies (e.g., rechargeable batteries, fuel cells, and water splitting devices) enabled by low-cost, earth-abundant materials. One of the most promising sustainable technologies is transforming earth-abundant molecules and compounds into value-added fuels, chemicals, and materials with electricity converted from solar and wind energy using electrolyzers. Moreover, as such an approach stores energy from intermittent sources in chemical bonds, renewable electricity can be regenerated utilizing fuel cells to meet our energy needs at scale and on-demand. Unfortunately, the cost and efficiency of these clean energy technologies have been hampered by the slow kinetics of oxygen electrocatalysis, currently requiring costly noble-metal-based catalysts to drive these electrochemical reactions at practical rates. To tackle this challenge, transition metal compounds, such as oxides and nitrides, have been utilized as low-cost, non-precious catalysts for these sustainable energy technologies. However, the best-known non-precious catalysts to date are still much less active and stable than their precious-metal-based counterparts, particularly in acidic systems. Thus, it is crucial to elucidate the activity and stability design principles (i.e., descriptors) of transition metal compounds for these electrochemical systems. Such design principles can offer a mechanistic understanding of the physical origin of their activity and durability and provide new guiding principles to optimize these compounds for energy storage and chemical transformation. In this thesis, we combine electrochemical characterizations, X-ray spectroscopies, and ab initio calculations to develop intrinsic descriptors for tuning the activity and stability of transition metal oxides/nitrides for decarbonization. First, we leverage the inductive effect to design catalysts with optimized electronic structures and redox properties by incorporating highly acidic/electronegative metals into perovskite oxides and constructing hybrid organic-inorganic oxide-based catalysts with stronger tunability in electronic structures than pure oxides. Second, we establish descriptors and mechanistic insights for optimizing the stability of oxides/nitrides in acid by tuning the electronic structures, bonding interactions, and thus, dissolution energetics. Lastly, we examine opportunities to extend such a descriptor-centered approach to a data-driven materials design paradigm.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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