A novel tandem reactor design based on nano-Cu electrocatalysts and microbial biocatalysts for converting CO2 into ethylene and acetate

Abstract

CO₂ electrochemical conversion on copper electrocatalysts demonstrates selectivity and activity towards multicarbon compounds such as ethylene. However, the complex product distribution, as well as the wasted carbon and electrons in non-target products such as HCOOH, CO, and H₂, can significantly increase the energy input and separation costs. As a result, we designed an electro-bio tandem reactor using copper electrocatalysts and microorganisms to transform CO₂ into specific multicarbon compounds in both the gas and liquid phases. The unavoidable reducing products from electrocatalysis, including HCOOH in the liquid phase, and CO and H₂ in the gas phase, can be consumed and recycled as electron donors or better carbon feedstocks for selective acetate synthesis in Moorella thermoacetica via the Wood–Ljungdahl pathway. In neutral electrolytes, the faradaic selectivity of acetate in liquid products is the highest (79.6%) for Cu-based CO₂ electroreduction, and the electron conversion rate to ethylene and acetate is the highest for microbial electrosynthesis (8113.8 mmol h⁻¹ m⁻²), demonstrating a green design for CO₂ upcycling targeting multicarbon products via the parallel integration of electrocatalysis and fermentation.