Low-Energy Electrochemical Carbon Dioxide Capture Based on a Biological Redox Proton Carrier
Heping Xie, Wenchuan Jiang, Tao Liu, Yifan Wu, Yufei Wang, Bin Chen, Dawen Niu, Bin Liang
Abstract
Carbon capture and storage, in which CO2 is selectively removed and sequestrated from flue gas, is a promising strategy to mitigate CO2 emissions and global warming. Conventionally, CO2 capture involves an energy-consuming absorbent regeneration step by thermal decomposition (2.0–4.0 GJ ton−1 CO2), which accounts for the majority (60%–70%) of the total cost. Here, we propose an alternative electrochemical cycle to capture CO2 in an aqueous alkaline solution, facilitated by the pH swing effect from a proton-coupled electron transfer redox reaction of a biological proton carrier, riboflavin 5′-monophosphate sodium salt hydrate (FMN/FMNH2). Under lab conditions, an electrolysis cell implementing the FMN proton carrier demonstrates a high energy efficiency, with only 9.8 kJ mol−1 CO2 captured, which is much lower than traditional approaches using a monoethanolamine absorbent (2.0–4.0 GJ ton−1 CO2, 88–176 kJ mol−1 CO2). Thus, this system may contribute toward lowering the cost of CO2 capture.