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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Bifunctional Ionic Deep Eutectic Electrolytes for CO2 Electroreduction
AU - Halilu, Ahmed
AU - Hadj-Kali, Mohamed Kamel
AU - Hashim, Mohd Ali
AU - Yusoff, Rozita
AU - Aroua, Mohamed Kheireddine
PY - 2022/10/25
Y1 - 2022/10/25
N2 - CO2 is a low-cost monomer capable of promoting industrially scalable carboxylation reactions. Sustainable activation of CO2 through electroreduction process (ECO2R) can be achieved in stable electrolyte media. This study synthesized and characterized novel diethyl ammonium chloride−diethanolamine bifunctional ionic deep eutectic electrolyte (DEACl−DEA), using diethanolamine (DEA) as hydrogen bond donors (HBD) and diethyl ammonium chloride (DEACl) as hydrogen bond acceptors (HBA). The DEACl−DEA has −69.78 °C deep eutectic point and cathodicelectrochemical stability limit of −1.7 V versus Ag/AgCl. In the DEACl−DEA (1:3) electrolyte, electroreduction of CO2 to CO2•− was achieved at −1.5 V versus Ag/AgCl, recording a faradaic efficiency (FE) of 94%. After 350 s of continuous CO2 sparging, anasymptotic current response is reached, and DEACl−DEA (1:3) has an ambient CO2 capture capacity of 52.71 mol/L. However,DEACl−DEA has a low faradaic efficiency <94% and behaves like a regular amine during the CO2 electroreduction process whenmole ratios of HBA−HBD are greater than 1:3. The electrochemical impedance spectroscopy (EIS) and COSMO-RS analysesconfirmed that the bifunctional CO2 sorption by the DEACl−DEA (1:3) electrolyte promote the ECO2R process. According to theEIS, high CO2 coverage on the DEACl−DEA/Ag-electrode surface induces an electrochemical double layer capacitance (EDCL) of3.15 × 10−9 F, which is lower than the 8.76 × 10−9 F for the ordinary DEACl−DEA/Ag-electrode. COSMO-RS analysis shows thatthe decrease in EDCL arises due to the interaction of CO2 non-polar sites (0.314, 0.097, and 0.779 e/nm2) with that of DEACl(0.013, 0.567 e/nm2) and DEA (0.115, 0.396 e/nm2). These results establish for the first time that a higher cathodic limit beyond the typical CO2 reduction potential is a criterion for using any deep eutectic electrolytes for sustainable CO2 electroreduction process.
AB - CO2 is a low-cost monomer capable of promoting industrially scalable carboxylation reactions. Sustainable activation of CO2 through electroreduction process (ECO2R) can be achieved in stable electrolyte media. This study synthesized and characterized novel diethyl ammonium chloride−diethanolamine bifunctional ionic deep eutectic electrolyte (DEACl−DEA), using diethanolamine (DEA) as hydrogen bond donors (HBD) and diethyl ammonium chloride (DEACl) as hydrogen bond acceptors (HBA). The DEACl−DEA has −69.78 °C deep eutectic point and cathodicelectrochemical stability limit of −1.7 V versus Ag/AgCl. In the DEACl−DEA (1:3) electrolyte, electroreduction of CO2 to CO2•− was achieved at −1.5 V versus Ag/AgCl, recording a faradaic efficiency (FE) of 94%. After 350 s of continuous CO2 sparging, anasymptotic current response is reached, and DEACl−DEA (1:3) has an ambient CO2 capture capacity of 52.71 mol/L. However,DEACl−DEA has a low faradaic efficiency <94% and behaves like a regular amine during the CO2 electroreduction process whenmole ratios of HBA−HBD are greater than 1:3. The electrochemical impedance spectroscopy (EIS) and COSMO-RS analysesconfirmed that the bifunctional CO2 sorption by the DEACl−DEA (1:3) electrolyte promote the ECO2R process. According to theEIS, high CO2 coverage on the DEACl−DEA/Ag-electrode surface induces an electrochemical double layer capacitance (EDCL) of3.15 × 10−9 F, which is lower than the 8.76 × 10−9 F for the ordinary DEACl−DEA/Ag-electrode. COSMO-RS analysis shows thatthe decrease in EDCL arises due to the interaction of CO2 non-polar sites (0.314, 0.097, and 0.779 e/nm2) with that of DEACl(0.013, 0.567 e/nm2) and DEA (0.115, 0.396 e/nm2). These results establish for the first time that a higher cathodic limit beyond the typical CO2 reduction potential is a criterion for using any deep eutectic electrolytes for sustainable CO2 electroreduction process.
KW - General Chemical Engineering
KW - General Chemistry
U2 - 10.1021/acsomega.2c04739
DO - 10.1021/acsomega.2c04739
M3 - Journal article
C2 - 36312381
VL - 7
SP - 37764
EP - 37773
JO - ACS Omega
JF - ACS Omega
SN - 2470-1343
IS - 42
ER -