In a significant step toward a more sustainable future, scientists at Caltech have developed a system that can convert carbon dioxide directly into a durable, industrially useful plastic. The innovative process utilizes only CO₂, water, and electricity from renewable sources, effectively transforming a greenhouse gas into valuable materials. This new method, detailed in the journal Angewandte Chemie International Edition, mimics a key aspect of nature’s carbon cycle without relying on plants —a process sometimes referred to as artificial photosynthesis. The final product is a type of high-performance plastic known as a polyketone, valued for its strength and thermal stability in products ranging from car parts to sports equipment.

The breakthrough relies on a tandem system that links two separate chemical reactions in distinct loops. In the first step, a process known as electrochemical CO₂ reduction, or eCO₂R, utilizes electricity to convert carbon dioxide gas into a mixture of two smaller molecules: ethylene and carbon monoxide. By using a combination of copper and silver catalysts on special gas diffusion electrodes and recirculating the gas, the team successfully generated a gas stream with concentrations of over 11% ethylene and 14% carbon monoxide. These concentrations are significantly higher than those of previous methods, which often produced less than 5% and were a significant bottleneck in creating plastics.

The concentrated gas mixture is then fed into a second reactor for the polymerization step. Here, the ethylene and carbon monoxide monomers are bubbled through a solution containing a palladium catalyst, which stitches the small molecules together into long polymer chains, forming the polyketone plastic. A key achievement of the Caltech team was demonstrating that this entire two-step process could work together. “Most work in the literature focuses on either the first or the second step, separately and with pure feedstocks,” said lead author and Caltech graduate student Max Zhelyabovskiy in a university press release. “Not both.”

While the technology shows great promise, the researchers note it requires further refinement before it is ready for large-scale application. The system does not yet produce plastics with the same molecular weight as those made conventionally, and its commercial viability depends on access to cheap, renewable electricity. However, by demonstrating that a robust catalyst can produce plastic directly from the output of CO₂ reduction, even in the presence of impurities such as water vapor, the work opens a new frontier. “With our new work, we have taken a significant step in that direction,” said Theo Agapie, a Caltech professor of chemistry.

References

• Fesenmaier, K. & California Institute of Technology. (2025, June 24). Two-step system makes plastic from carbon dioxide, water and electricity. Phys.Org; California Institute of Technology. https://phys.org/news/2025-06-plastic-carbon-dioxide-electricity.html

• Zhelyabovskiy, M., Jung, H., Diaconescu, P. L., Peters, J. C., & Agapie, T. (2025). Plastic from co₂ , water, and electricity: Tandem electrochemical co₂ reduction and thermochemical ethylene‐co copolymerization. Angewandte Chemie International Edition, 64(24), e202503003. https://doi.org/10.1002/anie.202503003