Engineering material interfaces for advanced thermo‑optical‑electrochemical energy systems

Rising concentrations of greenhouse gas continue to fuel global warming, driving a critical need for technologies that both curb energy demand and valorize greenhouse‐gas emissions. This dissertation advances a materials‐interface approach that tackles the problem from two complementary angles: (i) optical–thermal system management for mitigating energy consumption and (ii) chemical energy conversion approaches for greenhouse gas mitigation. First, spectrally engineered metal-based nanostructured surfaces are designed and fabricated through scalable nanosphere and nanoimprint lithography. The coatings reflect mid-infrared radiation, generating localized radiative heating without external energy consumption, while preserving tunable visible functionalities such as transparency or aesthetic coloration. Building on these photonic design principles, the system extends radiative thermal control to a thermally regenerative electrochemical cycle, where a passive temperature gradient is harnessed to generate electricity from ambient heat without external charging. The second research thrust addresses methane, a potent greenhouse gas with a global warming potential approximately 25 times that of carbon dioxide, yet an abundant and underutilized carbon feedstock. Two reaction pathways under environmentally benign conditions are demonstrated. In the first, a photoelectrochemical scheme employs defect-engineered catalysts to suppress over-oxidation, achieving high Faradaic efficiency for the conversion of methane into liquid products. This is accomplished not only by reducing oxidation potential but also by minimizing the generation of hydroxyl radicals that typically lead to complete oxidation. In the second approach, an electro-Fenton-based system couples two-electron oxygen reduction at a cathode with photoelectrochemical glycerol oxidation at the anode, enabling bias-free methane oxidation under ambient conditions. Across both routes, systematic tuning of surface chemistry, electrolyte composition, and gas flow was investigated the optimized the methane valorization. By controlling heat and charge transport at the micro- and nanoscale, this work demonstrates how opto-thermal and electrochemical systems can be synergistically designed to reduce fossil fuel dependence, valorize greenhouse gases, and expand the functional boundaries of sustainable energy technologies. The findings collectively emphasize the transformative potential of materials science in shaping low-carbon, high-efficiency energy infrastructures for the future.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Woo, Ho Kun

Contributors dc:contributor

• Cai, Lili
• Lee, Tonghun
• Yang, Hong
• He, Jiajun

• Energy Conversion
• Heat Transfer
• Electrochemical Conversion

Statement dc:rights

• Copyright 2025 Woo, Ho Kun

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/130162

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F130162