Summary

The goal of my research has been to find cost-effective ways to decompose very low concentrations (2-1000 parts per million; ppm) of methane. If developed, such a process could be very useful for mitigating the global warming effect of methane emissions. Our general approach has been to identify a promising approach for oxidizing dilute methane, then to conduct parallel cost modeling and benchtop experiments in order to decide whether it could be practically deployable in the next few decades.

We began by studying photocatalysts, a class of materials that can decompose dilute pollutants including methane under ambient conditions. However, in my first two thesis chapters (listed below), we found that current photocatalysts' rates would have to improve >1000x to have a cost-plausible methane mitigation strategy. We then switched to catalyst-free 'gas-phase advanced oxidation' processes, starting with a process that destroys methane using chlorine radicals. This work is ongoing. I'm also working to publish a paper on PyOpticon, the open-source lab automation and control software that I developed to support this research.

Doctoral Thesis

Download here (41-MB .pdf file): resources/richard_thesis_final.pdf

First-Author Publications

A Humidity-Tolerant Photocatalyst for Methane Removal
Kessler, Randall, et al., Environmental Science and Technology (2025). Shared first authorship.
DOI: https://doi.org/10.1021/acs.est.5c16764

PyOpticon: An Open-Source Python Package for Laboratory Control, Automation, and Visualization
Randall and Majumdar, ACS Chemistry of Materials (2025)
DOI: https://doi.org/10.1021/acs.chemmater.5c00644

Cost Modeling of Photocatalytic Removal of Atmospheric Methane and Nitrous Oxide
Randall et al., Environmental Research Letters (2024)
DOI: doi.org/10.1088/1748-9326/ad4376

Under review: Efficiencies and Products of a Chlorine Radical Photoreactor for Dilute Methane Oxidation
Randall et al., submitted to Environmental Science and Technology (2025)

Other Publications

A semi-continuous process for co-production of CO2-free hydrogen and carbon nanotubes via methane pyrolysis
Sun et al., Cell Reports Physical Science (2023)
Preprint: https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864(23)00103-0

Low-temperature carbon dioxide conversion via reverse water-gas shift thermochemical looping with supported iron oxide
Sun et al., Cell Reports Physical Science (2023)
Preprint: https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864(23)00389-2

Requirements for CO2-free hydrogen production at scale
Sun et al., Joule (2024)
Preprint: https://www.cell.com/joule/abstract/S2542-4351(24)00238-1

Conference Posters

American Geophysical Union 2023
American Geophysical Union 2024