Toward abiotic sugar synthesis from CO2 electrolysis

Although steady progress has been achieved toward upcycling waste CO2 through diverse catalytic strategies, each approach has distinct limitations, hampering the generation of complex products like sugars. Here, we provide a roadmap that evaluates the feasibility associated with state-of-the-art electrochemical processes eligible for converting CO2 into glycolaldehydes and formaldehydes, both essential components for sugar generation through the formose reaction. We establish that even in low concentrations, glycolaldehyde plays a crucial role as an autocatalytic initiator during sugar formation and identify formaldehyde production as a bottleneck. Our study demonstrates the chemical resilience of the formose reaction successfully carried out in the chemically complex CO2 electrolysis product stream. This work reveals that CO2-initiated sugars constitute an adequate feedstock for fast-growing and genetically modifiable Escherichia coli. Altogether, we introduce a roadmap, supported by experimental evidence, that pushes the boundaries of product complexity achievable from CO2 electroconversion while integrating CO2 into life-sustaining sugars. [Display omitted] •A roadmap of CO2 upcycling modules leading to abiotic sugar generation was established•CO2 electroconversion to formaldehyde and glycolaldehyde was experimentally assessed•Glycolaldehyde from CO2 initiated sugar formation in a chemically complex medium•Sugars initiated by CO2-derived glycolaldehyde served as feedstock for Escherichia coli The conversion of CO2 to drop-in and complex products would be transformative to the field of CO2 upcycling. However, limited progress has been achieved using heterogeneous catalysts due to the complexity of favoring one out of the many possible reaction pathways and associated high energy penalties. Here, we establish a pathway toward the generation of a complex product in sugars from CO2 by sequentially combining existing CO2 conversion modules. Initial CO2 products in glycolaldehyde and formaldehyde react together through the formose reaction to generate sugars. We experimentally evaluated commonly reported electrochemical platforms for formaldehyde and glycolaldehyde production from CO2. As a result, we determined that glycolaldehyde even in low quantities is a necessary initiator for sugar formation. Sugars could be an important feedstock in biomanufacturing; therefore, we demonstrated that sugars formed with CO2-derived glycolaldehyde could be used as feedsto