Highly efficient electrochemical upgrade of CO2 to CO using AMP capture solution as electrolyte

Electrochemical CO2 reduction reaction (ECO2RR) offers an eco-friendly way to produce value-added products by utilizing the waste CO2 from the environment. Recently, amines have been utilized as electrolytes for direct conversion of CO2 but processes were energy-intensive and lack selectivity due to the formation of highly stable carbamate. 2-amino-2-methyl-1-propanol (AMP) is a sterically hindered amine, produces less stable carbamate, and generates more HCO3-. Herein, ECO2RR performance using AMP aqueous solution as electrolyte was investigated over Ag, Cu, and Zn metal electrodes. Ultimately, 91 +/- 7% CO selectivity on HCl modified polycrystalline Ag electrode at -0.91 V vs RHE in 1 M AMP aqueous solution in the presence of CTAB was achieved, 1.7 times greater than in 1 M aqueous ethanolamine (MEA) solution. Synergetic effects of unstable AMP-carbamate, generation of nano-agglomerates on pitted/porous Ag surface arising from HCl treatment, and a compact electrical double layer due to CTAB present are responsible for the high selectivity of CO. Our findings provide the understanding of electrode-electrolyte interactions and offer a facile strategy to directly convert CO2 to CO from CO2 capture solutions. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the performance of the electrochemical CO2 reduction reaction using an AMP aqueous solution as the electrolyte. It achieves high selectivity for CO production, which is attributed to the unstable AMP-carbamate, generation of nano-agglomerates on the pitted/porous Ag surface, and the compact electrical double layer formed by CTAB.