Breakthrough catalyst turns methane into ethanol using only sunlight and air
image: Catalyst structure, photocatalytic performance, and catalytic pathway
Credit: Li Li & Yongfu Sun.
Scientists have unveiled a sunlight-powered catalyst that transforms methane—the main component of natural gas—directly into ethanol, a high-value liquid fuel and chemical feedstock. The new material, described today in Frontiers in Energy, achieves an apparent quantum efficiency of 9.4 %, a record for photocatalytic methane-to-ethanol conversion, while operating under near-ambient conditions.
The breakthrough centers on a covalent triazine framework (CTF-1) engineered with an intramolecular junction that separates electrons and holes onto distinct benzene and triazine units. This dual-site architecture not only accelerates charge separation but also steers the reaction away from wasteful over-oxidation to CO₂, a persistent problem in methane activation.
“By spatially separating the sites that generate hydroxyl radicals from those that stabilize oxygen, we can break the C–H bond in methane and then stitch the fragments into ethanol instead of CO₂,” said senior author Dr. Yongfu Sun of the University of Science and Technology of China. “It’s like having two specialized hands on the same molecule, each doing one job perfectly.”
Key results
- Selectivity > 90 % for ethanol over methanol, formic acid, or CO₂.
- Stable performance for 50 hours in a continuous-flow reactor with no detectable degradation.
- Isotopic labeling with ¹³CH₄ confirmed that all carbon atoms in the ethanol originate from methane, ruling out contamination.
Mechanism in brief
- Light excites electrons in CTF-1; holes localize on triazine rings, electrons on benzene rings.
- Triazine-bound water forms hydroxyl radicals (•OH) that abstract hydrogen from CH₄, yielding •CH₃.
- Benzene-bound O₂ traps the methyl radical and guides it through a two-carbon coupling pathway to ethanol.
The team further boosted activity by decorating CTF-1 with sub-nanometer PtOx clusters, which act as electron shuttles. Packed-bed flow experiments showed six-fold higher ethanol production than benchmark TiO₂ or g-C₃N₄ catalysts under identical solar irradiation.
Path to scale
The researchers outline a roadmap that couples the catalyst with continuous-flow microreactors powered by renewable electricity or concentrated solar light. Such integration could slash the carbon footprint of ethanol production while monetizing stranded or flared methane.
“Industrial deployment will require reactor engineering and catalyst manufacturing at scale, but the fundamental science hurdle—selective C–H activation—has been cleared,” Sun noted.
About the paper
“Intramolecular junction for methane photooxidation to ethanol” by Li Li & Yongfu Sun is published in Frontiers in Energy (2025, 19:257–259). https://link.springer.com/article/10.1007/s11708-025-0993-5