Producing formic acid at low pH values by electrochemical CO2 reduction

Oßkopp, Marvin; Lowe, A. C.; Lobo, Carlos Manuel Silva; Baranyai, Sebastian; Khoza, Thulile; Auinger, Michael; Klemm, Elias

doi:10.1016/j.jcou.2021.101823

Cited by 32 publications

(15 citation statements)

References 38 publications

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“…During CPE, H + was rapidly consumed by CO 2 RR, which may result in a locally higher pH microenvironment by diffusion limitation from porous confinement. [ 25 ] The higher pH microenvironment is significant to obtain high selectivity of acidic CO 2 RR, [ 6a,26 ] allowing high performance of TDPE‐PPSU at pH 1.8.…”

Section: Resultsmentioning

confidence: 99%

“…[ 5 ] According to the Pourbaix diagram, the turning point for CO 2 RR to FA/formate is located at pH 3.77, corresponding to the p K a of FA. [ 6 ] Utilizing acidic conditions below pH 3.77 could directly generate FA, overcoming the carbonation problem. However, when pH is sufficiently low, HER can quickly become kinetically dominant, [ 6a ] causing low Faradaic efficiency of FA.…”

Section: Introductionmentioning

confidence: 99%

“…[ 6 ] Utilizing acidic conditions below pH 3.77 could directly generate FA, overcoming the carbonation problem. However, when pH is sufficiently low, HER can quickly become kinetically dominant, [ 6a ] causing low Faradaic efficiency of FA. Thus, designing robust electrodes with low HER and high FA selectivity under acidic conditions is of great importance.…”

Section: Introductionmentioning

confidence: 99%

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Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Yan

Pan

Liu

et al. 2023

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Direct electrochemical CO2 reduction to formic acid (FA) instead of formate is a challenging task due to the high acidity of FA and competitive hydrogen evolution reaction. Herein, 3D porous electrode (TDPE) is prepared by a simple phase inversion method, which can electrochemically reduce CO2 to FA in acidic conditions. Owing to interconnected channels, high porosity, and appropriate wettability, TDPE not only improves mass transport, but also realizes pH gradient to build higher local pH micro‐environment under acidic conditions for CO2 reduction compared with planar electrode and gas diffusion electrode. Kinetic isotopic effect experiments demonstrate that the proton transfer becomes the rate‐determining step at the pH of 1.8; however, not significant in neutral solution, suggesting that the proton is aiding the overall kinetics. Maximum FA Faradaic efficiency of 89.2% has been reached at pH 2.7 in a flow cell, generating FA concentration of 0.1 m. Integrating catalyst and gas–liquid partition layer into a single electrode structure by phase inversion method paves a facile avenue for direct production of FA by electrochemical CO2 reduction.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Yan

Pan

Liu

et al. 2023

Small

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“…However, abundant H + /H 3 O + at the cathode will promote the competing HER in an acidic environment (similar to the CSA-MEA configuration with acid crossover), thereby reducing the FE of the CO 2 RR. Advanced catalyst and/or reaction system design that can suppress the HER under acidic conditions, such as by using a catholyte with a high concentration of alkali cations, is highly desired to further improve the efficiency of the CO (2) RR. − …”

Section: Flow Cell Design and Developmentmentioning

confidence: 99%

Progress and Understanding of CO₂/CO Electroreduction in Flow Electrolyzers

Jiao

Lü

2022

ACS Catal.

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The electroreduction of CO 2 and CO into valuable chemicals and fuels powered by renewable electricity can tackle anthropogenic carbon emissions and close the carbon cycle. However, both CO 2 and CO have low solubility in aqueous electrolytes, affording their sluggish mass transport across the electrolyte. CO 2 /CO electroreduction in a flow electrolyzer can tackle this problem by directly delivering the gaseous reactant to the electrode surface. Significant progress has been made recently in simultaneously obtaining high reaction rates and high product selectivity using flow cell configurations. This perspective highlights how different flow cell designs impact CO 2 /CO electroreduction and outlines potential strategies that may further improve the cell performance. The challenges and opportunities related to fundamental and engineering aspects are also discussed.

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“…Generally, the CO 2 RR yields formic acid operating at acidic conditions below the pKa of formic acid (3.8) and formate productions at highly alkaline electrolyte systems (pH > 8). [87] Some excellent reviews also have summarized the state-of-art electrocatalysts for electrocatalytic conversion of CO 2 into formic acid/formate. [35,42,88] Nevertheless, it is also critical to obtain highly concentrated formic acid/formate from CO 2 RR, as a highconcentration liquid product in downstream separation processes will require low energy consumption, thereby compromising the overall CO 2 RR economic feasibility.…”

Section: Introductionmentioning

confidence: 99%

High‐Concentration Electrosynthesis of Formic Acid/Formate from CO₂: Reactor and Electrode Design Strategies

Kuang

Rabiee

et al. 2023

Energy & Environ Materials

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The electrochemical CO2 reduction reaction (CO2RR), driven by renewable energy, provides a potential carbon‐neutral avenue to convert CO2 into valuable fuels and feedstocks. Conversion of CO2 into formic acid/formate is considered one of the economical and feasible methods, owing to their high energy densities, and ease of distribution and storage. The separation of formic acid/formate from the reaction mixtures accounts for the majority of the overall CO2RR process cost, while the increment of product concentration can lead to the reduction of separation cost, remarkably. In this paper, we give an overview of recent strategies for highly concentrated formic acid/formate products in CO2RR. CO2RR is a complex process with several different products, as it has different intermediates and reaction pathways. Therefore, this review focuses on recent study strategies that can enhance targeted formic acid/formate yield, such as the all‐solid‐state reactor design to deliver a high concentration of products during the reduction of CO2 in the electrolyzer. Firstly, some novel electrolyzers are introduced as an engineering strategy to improve the concentration of the formic acid/formate and reduce the cost of downstream separations. Also, the design of planar and gas diffusion electrodes (GDEs) with the potential to deliver high‐concentration formic acid/formate in CO2RR is summarized. Finally, the existing technological challenges are highlighted, and further research recommendations to achieve high‐concentration products in CO2RR. This review can provide some inspiration for future research to further improve the product concentration and economic benefits of CO2RR.

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Producing formic acid at low pH values by electrochemical CO2 reduction

Cited by 32 publications

References 38 publications

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Progress and Understanding of CO₂/CO Electroreduction in Flow Electrolyzers

High‐Concentration Electrosynthesis of Formic Acid/Formate from CO₂: Reactor and Electrode Design Strategies

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Producing formic acid at low pH values by electrochemical CO2 reduction

Cited by 32 publications

References 38 publications

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO2 to Formic acid

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO2 to Formic acid

Progress and Understanding of CO2/CO Electroreduction in Flow Electrolyzers

High‐Concentration Electrosynthesis of Formic Acid/Formate from CO2: Reactor and Electrode Design Strategies

Contact Info

Product

Resources

About

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Phase‐Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid

Progress and Understanding of CO₂/CO Electroreduction in Flow Electrolyzers

High‐Concentration Electrosynthesis of Formic Acid/Formate from CO₂: Reactor and Electrode Design Strategies