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Gas-phase electrochemical CO2 reduction on silver-copper BTC MOF in a zero-gap membrane electrode assembly.

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Title: Gas-phase electrochemical CO2 reduction on silver-copper BTC MOF in a zero-gap membrane electrode assembly.
Authors: Nambi, Ashwin1 (AUTHOR), Chatzitakis, Athanasios2 (AUTHOR), Olsbye, Unni2 (AUTHOR), Hjelm, Johan1 (AUTHOR), Zhao, Yujie1 (AUTHOR), Kaiser, Andreas1 (AUTHOR) akai@dtu.dk
Source: Electrochimica Acta. Dec2024, Vol. 506, pN.PAG-N.PAG. 1p.
Subjects: Hydrogen evolution reactions, Carbon dioxide, Ionic structure, Water supply, Ligands (Chemistry), Electrolytic reduction
Abstract: • A fast co-precipitation method using a deprotonated BTC ligand was developed to be able to incorporate Ag ions into the structure of bimetallic AgCu-BTC MOFs. • For the first time, the electrocatalytic reduction of CO 2 was investigated in the gas phase and as a function of different humidity levels on AgCu-BTC MOF. • The presence of Ag in the Cu-BTC based framework improves the gas phase CO 2 reduction reaction towards CO and suppresses the competing H 2 evolution. • Lowering the humidity levels in the CO 2 gas stream enhances CO production due to the reduced availability of water. Bimetallic AgCu-BTC MOFs, derived from Cu-BTC (HKUST-1), have been synthesized by fast co-precipitation method and evaluated for CO 2 reduction reaction (CO 2 RR) using humidified CO 2 gas in a zero-gap configuration. Three compositions with varying Ag content – AgCu-1 (9.4 at.%), AgCu-2 (12.5 at.%), and AgCu-3 (16.5 at.%) – were characterized by SEM-EDS, PXRD, FTIR, and XPS. These structural analyzes confirmed the formation of a low-crystalline AgCu-BTC MOF with Ag+1 ions coordinated to the BTC framework. Electrochemical tests (CV and LSV) revealed that AgCu-3 MOF, with the highest Ag content (16.5 at.%), exhibited a more positive onset potential at -0.65 V vs Ag/AgCl compared to HKUST-1 MOF, indicating enhanced CO 2 RR activity, owing to Ag incorporation. Constant potential (CP) experiments showed that AgCu-3 MOF predominantly produced CO and H 2 , achieving faradaic efficiency of approximately 65 % for CO production and 5 % for H 2 production. Moreover, lowering the relative humidity (RH%) in the inlet CO 2 gas stream from 80% to 20% increased CO production by 2-fold from 6.2 µmol s-1 cm-2 to 13 µmol s-1 cm-2, simultaneously suppressing the hydrogen evolution reaction (HER). This reduction in humidity resulted in an increased local concentration of CO 2 at the catalyst site, leading to an enhanced CO 2 RR rate. However, substantial morphological changes have been observed in the AgCu-3 MOF after the CP experiment under humid CO 2 reduction conditions. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:• A fast co-precipitation method using a deprotonated BTC ligand was developed to be able to incorporate Ag ions into the structure of bimetallic AgCu-BTC MOFs. • For the first time, the electrocatalytic reduction of CO 2 was investigated in the gas phase and as a function of different humidity levels on AgCu-BTC MOF. • The presence of Ag in the Cu-BTC based framework improves the gas phase CO 2 reduction reaction towards CO and suppresses the competing H 2 evolution. • Lowering the humidity levels in the CO 2 gas stream enhances CO production due to the reduced availability of water. Bimetallic AgCu-BTC MOFs, derived from Cu-BTC (HKUST-1), have been synthesized by fast co-precipitation method and evaluated for CO 2 reduction reaction (CO 2 RR) using humidified CO 2 gas in a zero-gap configuration. Three compositions with varying Ag content – AgCu-1 (9.4 at.%), AgCu-2 (12.5 at.%), and AgCu-3 (16.5 at.%) – were characterized by SEM-EDS, PXRD, FTIR, and XPS. These structural analyzes confirmed the formation of a low-crystalline AgCu-BTC MOF with Ag+1 ions coordinated to the BTC framework. Electrochemical tests (CV and LSV) revealed that AgCu-3 MOF, with the highest Ag content (16.5 at.%), exhibited a more positive onset potential at -0.65 V vs Ag/AgCl compared to HKUST-1 MOF, indicating enhanced CO 2 RR activity, owing to Ag incorporation. Constant potential (CP) experiments showed that AgCu-3 MOF predominantly produced CO and H 2 , achieving faradaic efficiency of approximately 65 % for CO production and 5 % for H 2 production. Moreover, lowering the relative humidity (RH%) in the inlet CO 2 gas stream from 80% to 20% increased CO production by 2-fold from 6.2 µmol s-1 cm-2 to 13 µmol s-1 cm-2, simultaneously suppressing the hydrogen evolution reaction (HER). This reduction in humidity resulted in an increased local concentration of CO 2 at the catalyst site, leading to an enhanced CO 2 RR rate. However, substantial morphological changes have been observed in the AgCu-3 MOF after the CP experiment under humid CO 2 reduction conditions. [ABSTRACT FROM AUTHOR]
ISSN:00134686
DOI:10.1016/j.electacta.2024.144763