The inhibition of the proton donor ability of bicarbonate promotes the electrochemical conversion of CO2 in bicarbonate solutions

Gutiérrez-Sánchez, Oriol; Daems, Nick; Offermans, W. K.; Birdja, Yuvraj Y.; Bulut, Metin; Pant, Deepak; Breugelmans, Tom

doi:10.1016/j.jcou.2021.101521

Cited by 31 publications

(40 citation statements)

References 27 publications

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“…identified that, when the concentration of bicarbonate is higher (>1 M), bicarbonate acts as a proton donor instead of a carbon donor, promoting to a great extent the Hydrogen Evolution Reaction (HER), in accordance with the experimental observations done up to date [66] . This effect was recently confirmed by Gutierrez‐Sanchez et al., where the proton donor ability of bicarbonate was inhibited by covering the surface of the electrode with a hydrophobic layer, thus allowing only CO 2 to trespass and increasing the selectivity to carbon products by 60 % [61,67] . They conclude that, since the desorbed CO 2 from bicarbonate is most likely the main electrochemical active species, to achieve high selectivity it is important to promote its release and avoid bicarbonate to act as a proton donor.…”

Section: Post‐capture Electrochemical Co2 Conversionsupporting

confidence: 73%

“…Bicarbonate can be easily stored and delivered to the electrochemical reactor. However, its feasibility as a substrate for the direct electrochemical bicarbonate reduction reaction has been discussed within the community for a long time, since extremely low FE towards carbon products have been observed when bicarbonate electrolytes (that have not been previously purged or saturated with CO 2 ) are used, with H 2 being the main product [61] …”

Section: Post‐capture Electrochemical Co2 Conversionmentioning

confidence: 99%

“…However, its feasibility as a substrate for the direct electrochemical bicarbonate reduction reaction has been discussed within the community for a long time, since extremely low FE towards carbon products have been observed when bicarbonate electrolytes (that have not been previously purged or saturated with CO 2 ) are used, with H 2 being the main product. [61] The role of bicarbonate in the eCO 2 R has been continuously studied and debated. On the one hand, some reports claimed that bicarbonate is reduced in pure (or saturated with CO 2 ) bicarbonate electrolytes acting as a substrate of the electrochemical reduction reaction.…”

Section: Co 2 Conversion From Bicarbonatementioning

confidence: 99%

“…[66] This effect was recently confirmed by Gutierrez-Sanchez et al, where the proton donor ability of bicarbonate was inhibited by covering the surface of the electrode with a hydrophobic layer, thus allowing only CO 2 to trespass and increasing the selectivity to carbon products by 60 %. [61,67] They conclude that, since the desorbed CO 2 from bicarbonate is most likely the main electrochemical active species, to achieve high selectivity it is important to promote its release and avoid bicarbonate to act as a proton donor.…”

Section: Co 2 Conversion From Bicarbonatementioning

confidence: 99%

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A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

et al. 2022

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To valorize waste CO2, capturing and utilizing it to produce chemical building blocks is currently receiving a lot of attention. In this respect, amine and alkali base solutions have shown to be efficient CO2 capturing solutions and electrochemical CO2 conversion is a promising technology to convert CO2 and, as such, reduce greenhouse gas emissions. However, to date, CO2 capture and utilization (CCU) technologies have been investigated almost exclusively as separate processes. This has the disadvantage that CO2 has to be desorbed and compressed from the capture solution before sending it to the CO2 electrolyzer, seriously increasing the capital and operational costs of the overall technology. To improve the valorization potential of the CCU technologies, integrating both technologies by directly utilizing the capture solution as an electrolyte for the electrochemical CO2 reduction (eCO2R) is a highly promising approach. This technology is however limited by low Faradaic efficiencies (FE) and partial current densities that can be achieved with these solutions. The main reason for this is the slow CO2 release rate at the catalytic interphase. Nevertheless, in recent years, in light of tackling these challenges, several studies successfully managed to decrease the costs of the CO2 capturing step and to electrochemically convert more efficiently the CO2 capture solutions. Herein, we review the status of the integrated CO2 capture and electrochemical conversion technology, discussing the recent developments and advances both in the field of CO2 capture and eCO2R.

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Section: Post‐capture Electrochemical Co2 Conversionsupporting

confidence: 73%

Section: Post‐capture Electrochemical Co2 Conversionmentioning

confidence: 99%

Section: Co 2 Conversion From Bicarbonatementioning

confidence: 99%

Section: Co 2 Conversion From Bicarbonatementioning

confidence: 99%

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A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

et al. 2022

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“…23 However, in this case, because HCO 3 − acts as a substrate for both CO 2 R and HER, it promotes the HER even more over the CO 2 R. 24 In our recent study, the inhibiting mechanism of cationic surfactants was confirmed also in HCO 3 − electrolytes, and it was proven that they play a similar role (but with higher impact) in inhibiting the HER in this type of HCO 3 − electrolytes compared to its CO 2 -saturated analogues. 21 To summarize, because HCO 3 − is a polar molecule, it is also partially repelled after the nonpolar layer is formed, thereby limiting its role in the proton supplier, as it can no longer reach the active sites as such but it can still liberate CO 2 first, which can then travel through the nonpolar channels to the active zone (Figure 3). Its role as the proton donor for the HER is thereby inhibited, as this would need it to reach the active sites intact.…”

Section: Introductionmentioning

confidence: 99%

Effects of Benzyl-Functionalized Cationic Surfactants on the Inhibition of the Hydrogen Evolution Reaction in CO₂ Reduction Systems

Gutiérrez-Sánchez

Daems

Bulut

et al. 2021

ACS Appl. Mater. Interfaces

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Cationic surfactants, mainly hexadecyl cetrimonium bromide (CTAB), are widely used in electrocatalysis to affect the selectivity of the reaction, specifically to inhibit the hydrogen evolution reaction (HER) in CO2 reduction (CO2R) systems. However, little research has been done on the modification of the functional groups present in such surfactants in order to promote this HER-inhibiting effect. In this work, the effectiveness of CTAB was promoted by substituting a methyl group of the quaternary amine for a benzyl group. This cationic surfactant, cetalkonium chloride (CKC), increased the hydrophobicity of the surface of the electrode, promoting the HER inhibition and the CO2R when HCO3 – is used as a carbon source, which allows combining capture and conversion in one and the same medium, making it industrially highly attractive. By performing a detailed electrochemical characterization, we proved that the benzyl group formed an enhanced hydrophobic layer on the surface of the electrode in addition to the alkyl chain of the surfactant, showing higher effectiveness compared to CTAB. In fact, the Faradaic efficiency of the CO2R increased from 39 to 66% in saturated HCO3 – electrolytes by using CKC instead of CTAB as the HER inhibitor. This opens up a wide range of avenues for research on the application of surfactants in the field of electrocatalysis, because, as proven, a selective modification of it can tune the selectivity of the reaction, adding a new variable in the design of an efficient carbon capture and utilization system.

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Effects of Electrolyte Ionic Species on Electrocatalytic Reactions: Advances, Challenges, and Perspectives

Lü

Zhou

et al. 2023

Advanced Energy Materials

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Electrolytes have a profound impact on the chemical environment of electrocatalysis, influencing the reaction rate and selectivity of products. Experimental and theoretical studies have extensively investigated the interaction mechanisms between electrolyte ions (i.e., alkali metal cations, carbonate anions) and reactants or the catalyst surface in electrocatalytic reactions such as the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, water oxidation reaction, and CO 2 reduction reaction. Past studies have demonstrated a noticeable dependence of electrochemical reaction activity and selectivity on the identity of electrolyte ions. However, few overviews have comprehensively and specifically discussed the effects of electrolyte cations and anions on common electrochemical reactions. In order to clarify and give more insights on this research area, this review aims to summarize and highlight recent progress in understanding the effects of various electrolyte ionic species and their influence mechanisms in diverse electrocatalytic reactions for water splitting, H 2 O 2 production, and CO 2 reduction. The challenges and perspectives on the effect of electrolyte ions in electrocatalysis are also presented.

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The inhibition of the proton donor ability of bicarbonate promotes the electrochemical conversion of CO2 in bicarbonate solutions

Cited by 31 publications

References 27 publications

A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

Effects of Benzyl-Functionalized Cationic Surfactants on the Inhibition of the Hydrogen Evolution Reaction in CO₂ Reduction Systems

Effects of Electrolyte Ionic Species on Electrocatalytic Reactions: Advances, Challenges, and Perspectives

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The inhibition of the proton donor ability of bicarbonate promotes the electrochemical conversion of CO2 in bicarbonate solutions

Cited by 31 publications

References 27 publications

A State‐of‐the‐Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems

A State‐of‐the‐Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems

Effects of Benzyl-Functionalized Cationic Surfactants on the Inhibition of the Hydrogen Evolution Reaction in CO2 Reduction Systems

Effects of Electrolyte Ionic Species on Electrocatalytic Reactions: Advances, Challenges, and Perspectives

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A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

A State‐of‐the‐Art Update on Integrated CO₂ Capture and Electrochemical Conversion Systems

Effects of Benzyl-Functionalized Cationic Surfactants on the Inhibition of the Hydrogen Evolution Reaction in CO₂ Reduction Systems