Mechanistic and Stability Study of the Integrated CO2 Capture-Electroreduction Process in Ethanolamine Solution over Ni/NC Atomic Catalysts

Abstract

In recent years, the integrated systems for the cost-effective conversion of CO₂ into high-value products have emerged as a major research focus in advancing sustainable green chemistry. The integrated process not only addresses the high energy consumption during desorption but also simplifies the process and reduces costs. However, further improving CO₂ conversion efficiency and achieving system stability remain significant challenges. Here, we report an integrated CO₂ capture and electroreduction process (ICCE) using atomically dispersed Nickel catalysts (Ni/NC) for the direct electroreduction of CO₂ absorbed in 30 wt.% ethanolamine (MEA, MAE, EAE, DMEA) solutions to CO, achieving a high Faradaic efficiency of up to 91%. In addition, the authors compared the effects of different reaction temperatures and different partial pressures of CO₂ in the gas phase on the prolonged electroreduction reaction, and suggested that the integrated system maintaining a gas-liquid equilibrium, can be guaranteed to continuously electrolyze to produce CO at a high Faraday efficiency. Through multiple characterizations, like NMR spectroscopy and In-situ Raman spectroscopy, revealed that CO is primarily derived from interfacially regenerated free CO₂, while carbamate species are not directly reduced but instead adsorb on the Ni/NC catalyst surface as inhibitory intermediates.