Tandem amine scrubbing and CO2 electrolysis via direct piperazine carbamate reduction

Abstract

Transforming CO2 into valuable products presents a promising route for reducing emissions across various industry sectors. However, conventional methods, including sequential CO2 electrolysis or reverse water–gas shift reaction, depend on energy-intensive CO2 purification; while emerging reactive CO2 capture strategies still face challenges in designing optimal system components that enable efficient electrochemical regeneration without compromising catalytic performance. Here we systematically screen a broad library of amine-based absorbents to establish a design rationale for tandem amine scrubbing and CO2 electrolysis. We identify piperazine as an optimal capture medium and show that its carbamate form can be directly reduced using a nickel single-atom catalyst. This charge-neutral intermediate facilitates spontaneous adsorption, rapid transport and efficient C–N bond cleavage, enabling stable carbon monoxide production alongside in situ amine regeneration. The process achieves an energy efficiency of ~48.8 GJ per tonne CO, offering a scalable and energy efficient pathway towards carbon-neutral chemical feedstocks. Integrating CO2 capture and electrochemical conversion avoids the thermal release of CO2 and thus could potentially lower the energy needed to make useful products from CO2, but choosing optimal system components is still challenging. Here the authors use piperazine alongside a nickel catalyst for capture and achieve high energy efficiency and stable CO production.