Surface hydrogen‑bonded network boosts plasma‑driven CO2 to C2H4 conversion

Non‑thermal plasma (NTP) technology is gaining attention as a way to convert carbon dioxide directly into fuels and chemicals under ambient conditions, using H₂O vapor as a cheap and abundant hydrogen source. However, the intense electrical discharge dissociates H₂O into gaseous hydrogen (·H) and hydroxyl (·OH) radicals that react indiscriminately, leading to poor selectivity for desired multi‑carbon products such as ethylene (C₂H₄), a key feedstock for plastics and chemicals.

Now, a team of materials scientists led by Professors Tao Chen, Rong He, and Wenkun Zhu at Southwest University of Science and Technology (Mianyang, China) has developed a ternary metal‑cluster organic framework (CeHfZr) that overcomes this limitation. The catalyst, reported in the journal Nano Research on July 9, 2026, features a UiO‑66‑type structure doped with cerium, hafnium, and zirconium. When exposed to H₂O vapor, the catalyst’s abundant Lewis acid sites capture H₂O molecules, which assemble into an interconnected hydrogen‑bonded network on the surface.

“This hydrogen‑bonded network acts as a protective and functional layer,” explains Prof. Tao Chen. “Instead of letting high‑energy electrons dissociate gaseous H₂O into free‑floating radicals, the network confines and ionizes H₂O in situ, producing solvated ·H and ·OH radicals right at the catalytic sites.” The solvated ·H radical rapidly converts to adsorbed atomic hydrogen (∗H) via proton transfer along the hydrogen‑bonded network, while the ·OH radical serves as mild oxidants to remove carbon deposits that would otherwise deactivate the catalyst.

In tests using a dielectric‑barrier discharge plasma reactor with 20% CO₂ (simulating industrial exhaust), the CeHfZr catalyst achieved a CO₂ conversion of about 26% and a C₂H₄ production rate of 164.6 μmol per gram per hour, nearly 15 times higher than that of the cerium‑only analogue. Notably, no oxygenated by‑products (such as ethanol or propanol) were detected, indicating that the reaction proceeds through a deep deoxygenation pathway: CO₂ is first reduced to adsorbed CO (∗CO), which then undergoes hydrogen‑assisted C-O bond cleavage followed by C-C coupling to form C₂H₄.

“Our work reveals that the hydrogen‑bonded microenvironment not only supplies hydrogen atoms in a controlled manner but also optimizes the plasma discharge mode, shifting from gas‑phase to surface‑mediated catalysis,” adds Prof. Rong He. “This synergy is key to achieving high selectivity toward C₂H₄ rather than a messy mixture of hydrocarbons and oxygenates.”

The team also performed in‑situ infrared spectroscopy, electron paramagnetic resonance, and electrochemical impedance measurements to confirm the mechanism. They found that the mixed‑metal cluster structure creates lattice distortions and unsaturated metal sites that strongly adsorb both CO₂ and H₂O, while the enhanced conductivity and lower work function of CeHfZr facilitate electron transfer to activate intermediates.

The researchers believe this strategy could be extended to other plasma‑catalytic systems that convert CO₂‑rich flue gases (especially those with H₂O vapor) into valuable chemicals. “C₂H₄ is one of the most important building blocks in the chemical industry,” says Prof. Wenkun Zhu. “If we can tap into waste CO₂ and moisture from power plants or factories to produce it, we not only reduce greenhouse gas emissions but also create a circular carbon economy.”

The study was supported by the National Natural Science Foundation of China (U2267224, U23A20105), the Sichuan Science and Technology Program, and other regional funding bodies (SKLIVGR-2024-03). The authors declare no competing interests.

DOI Link:

https://doi.org/10.26599/NR.2026.94909015

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.