CO<sub>2</sub> upgrading into bioproducts using a two-step abiotic-biotic system.

Lee, Geonhui; Jo, Hye-Jin; Choi, Jihoon; Guzman, Maria Fonseca; Shan, Yu; Le, Han K D; Feijoo, Julian; Soland, Nathan et al. · Proc Natl Acad Sci U S A · 2025

basic_science · Level V

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Abstract

The valorization of CO<sub>2</sub> to chemicals beyond C<sub>1-2</sub> products is receiving significant interest; however, the direct electrosynthesis of C<sub>n</sub> molecules (n > 4) remains a challenge. Here, we present a two-step abiotic-biotic system for upgrading CO<sub>2</sub> into the biopolymer, poly(3-hydroxybutyrate). In the electrolysis system, CO<sub>2</sub> is converted into C<sub>2</sub> oxygenates using a Cu-Ag tandem electrocatalyst. The electrolysis process generates a liquid stream containing ~ 200 mM acetate in a bio-compatible electrolyte. This electrosynthesized acetate is then fed to a bioreactor, where the substrate is upgraded by <i>Cupriavidus necator</i> to biopolymer with a maximum rate of 32 ± 3.5 mg L<sup>-1</sup> h<sup>-1</sup>. We further demonstrate the purification of the resulting biopolymer into a powder. The high productivity of the abiotic-biotic system demonstrates its feasibility for sustainable chemical manufacturing.