Achieving High Selectivity and Stability in Electrocatalytic CO2 Reduction in Acidic Media via Ion Confinement

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Angewandte Chemie Int Ed, Wiley-VCH

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Angewandte Chemie International Edition, EarlyView.

To address the challenge of carbonate deposition during CO2RR in acidic MEA, this work proposes a solid‐state electrolyte‐mediated ion‐confinement strategy. Using this approach, the effects of various confined anions and cations on the reaction were systematically investigated. Ultimately, we achieved a FECO of 98.4% and remarkably long stability of 460 h, under acidic conditions with non‐ or dilute‐alkali metal cations. ABSTRACT Immobilizing cation‐type organic molecules at the cathode represents a transformative strategy for enhancing the electrocatalytic CO2 reduction reaction (CO2RR) in acidic or pure water. However, the investigation of anion‐type organic molecules is missing, and the roles of cations and anions are not well understood, especially in the membrane electrode assembly (MEA) configuration. Employing an ionic‐confinement strategy mediated by a solid‐state electrolyte, we systematically investigate the influence of cation‐ and anion‐type organic molecules on CO2RR. Our findings show that cations in both cation‐ and anion‐type molecules play a crucial role in inhibiting the hydrogen evolution reaction and promoting CO2RR in MEA. Utilizing an anion‐type organic molecule, we achieved exceptional CO Faradaic efficiencies of 98.4% in H2SO4 media (pH = 1) and 95.8% in pure water‐fed MEAs on Ag. Additionally, with cation‐type organic molecules, we demonstrated robust operational stability of 150 h in H2SO4 (pH = 1) electrolyte and 460 h in an ultra‐low potassium concentration (2 mM) acidic electrolyte in MEA configuration. This work establishes a versatile framework for achieving high‐efficiency, long‐term CO2 electrolysis across diverse electrolyte environments, highlighting its potential for industrial‐scale application.

To address the challenge of carbonate deposition during CO₂RR in acidic MEA, this work proposes a solid-state electrolyte-mediated ion-confinement strategy. Using this approach, the effects of various confined anions and cations on the reaction were systematically investigated. Ultimately, we achieved a FE_CO of 98.4% and remarkably long stability of 460 h, under acidic conditions with non- or dilute-alkali metal cations.

Immobilizing cation-type organic molecules at the cathode represents a transformative strategy for enhancing the electrocatalytic CO₂ reduction reaction (CO₂RR) in acidic or pure water. However, the investigation of anion-type organic molecules is missing, and the roles of cations and anions are not well understood, especially in the membrane electrode assembly (MEA) configuration. Employing an ionic-confinement strategy mediated by a solid-state electrolyte, we systematically investigate the influence of cation- and anion-type organic molecules on CO₂RR. Our findings show that cations in both cation- and anion-type molecules play a crucial role in inhibiting the hydrogen evolution reaction and promoting CO₂RR in MEA. Utilizing an anion-type organic molecule, we achieved exceptional CO Faradaic efficiencies of 98.4% in H₂SO₄ media (pH = 1) and 95.8% in pure water-fed MEAs on Ag. Additionally, with cation-type organic molecules, we demonstrated robust operational stability of 150 h in H₂SO₄ (pH = 1) electrolyte and 460 h in an ultra-low potassium concentration (2 mM) acidic electrolyte in MEA configuration. This work establishes a versatile framework for achieving high-efficiency, long-term CO₂ electrolysis across diverse electrolyte environments, highlighting its potential for industrial-scale application.

Xuelei Lang, Ziyao Yang, Qiang Fang, Yuhui Zhang, Xinru Ning, Dazhong Zhong, Jinping Li, Qiang Zhao

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