Electrochemical CO2 reduction to methane with remarkably high Faradaic efficiency in the presence of a proton permeable membrane

Due to CO2 mass transfer limitation as well as the competition of hydrogen evolution reaction in electroreduction of CO2 in the aqueous electrolyte, Zn-based electrodes normally exhibit unsatisfying selectivity for CO production, especially at high potentials. In this work, we introduced a zinc myristate (Zn [CH3(CH2)12COO]2) hydrophobic layer on the surface of zinc foam electrode by an electrodeposition method. The obtained hydrophobic zinc foam electrode showed a high Faradaic efficiency (FE) of 91.8% for CO at −1.9 V (vs. saturated calomel electrode, SCE), which was a remarkable improvement over zinc foam (FECO = 81.87%) at the same potentials. The high roughness of the hydrophobic layer has greatly increased the active surface area and CO2 mass transfer performance by providing abundant gas-liquid-solid contacting area. This work shows adding a hydrophobic layer on the surface of the catalyst is an effective way to improve the electrochemical CO2 reduction performance.

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Fast operando spectroscopy tracking in situ generation of rich defects in silver nanocrystals for highly selective electrochemical CO2 reduction

Nature Communications ◽

10.1038/s41467-021-20960-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Xinhao Wu ◽

Yanan Guo ◽

Zengsen Sun ◽

Fenghua Xie ◽

Daqin Guan ◽

...

Keyword(s):

Active Sites ◽

Density Functional ◽

Co2 Reduction ◽

Density Functional Theory Calculations ◽

Defect Concentration ◽

Hydrogen Electrode ◽

Efficient Catalyst ◽

Faradaic Efficiency ◽

Electrochemical Co2 Reduction ◽

Cell Reactor

AbstractElectrochemical CO2 reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm−2 at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation.

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Electrochemical CO2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on Carbon-Supported Bimetallic Pd–Pt Nanoparticles

ACS Catalysis ◽

10.1021/acscatal.5b00602 ◽

2015 ◽

Vol 5 (7) ◽

pp. 3916-3923 ◽

Cited By ~ 232

Author(s):

Ruud Kortlever ◽

Ines Peters ◽

Sander Koper ◽

Marc T. M. Koper

Keyword(s):

Formic Acid ◽

Co2 Reduction ◽

Pt Nanoparticles ◽

Faradaic Efficiency ◽

Electrochemical Co2 Reduction ◽

Low Overpotential

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Visualisation and quantification of flooding phenomena in gas diffusion electrodes (GDEs) used for electrochemical CO2 reduction: A combined EDX/ICP–MS approach

10.26434/chemrxiv-2022-1v00j ◽

2022 ◽

Author(s):

Ying Kong ◽

Huifang Hu ◽

Menglong Liu ◽

Yuhui Hou ◽

Viliam Kolivoska ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Co2 Reduction ◽

Gas Diffusion ◽

Reduction Reaction ◽

Gas Diffusion Electrodes ◽

Cross Sectional ◽

Faradaic Efficiency ◽

Icp Ms ◽

Electrochemical Co2 Reduction ◽

Current Densities

The most promising strategy to up-scale the electrochemical CO2 reduction reaction (ec-CO2RR) is based on the use of gas diffusion electrodes (GDEs) that allow current densities close to the range of 1 A/cm2 to be reached. At such high current densities, however, the flooding of the GDE cathode is often observed in CO2 electrolysers. Flooding hinders the access of CO2 to the catalyst, and by thus leaving space for (unwanted) hydrogen evolution, it usually leads to a decrease of the observable Faradaic efficiency of CO2 reduction products. To avoid flooding as much as possible has thus become one of the most important aims of to-date ec-CO2RR engineering, and robust analytical methods that can quantitatively assess flooding are now in demand. As flooding is very closely related to the formation of carbonate salts within the GDE structure, in this paper we use alkali (in particular, potassium) carbonates as a tracer of flooding. We present a novel analytical approach —based on the combination of cross-sectional energy-dispersive X-ray (EDX) mapping and inductively coupled plasma mass spectrometry (ICP--MS) analysis— that can not only visualise, but can also quantitatively describe the electrolysis time dependent flooding in GDEs, leading to a better understanding of electrolyser malfunctions.

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Preparation of Metal Amalgam Electrodes and Their Selective Electrocatalytic CO2 Reduction for Formate Production

Catalysts ◽

10.3390/catal9040367 ◽

2019 ◽

Vol 9 (4) ◽

pp. 367 ◽

Cited By ~ 2

Author(s):

Syed Asad Abbas ◽

Seong-Hoon Kim ◽

Hamza Saleem ◽

Sung-Hee Ahn ◽

Kwang-Deog Jung

Keyword(s):

Current Density ◽

Co2 Reduction ◽

Active Phase ◽

Base Metals ◽

Metallic Component ◽

Faradaic Efficiency ◽

Amalgam Electrode ◽

Electrochemical Co2 Reduction ◽

The One ◽

Formate Production

Electrochemical CO2 reduction to produce formate ions has studied for the sustainable carbon cycle. Mercury in the liquid state is known to be an active metallic component to selectively convert CO2 to formate ions, but it is not scalable to use as an electrode in electrochemical CO2 reduction. Therefore, scalable amalgam electrodes with different base metals are tested to produce formate by an electrochemical CO2 reduction. The amalgam electrodes are prepared by the electrodeposition of Hg on the pre-electrodeposited Pd, Au, Pt and Cu nanoparticles on the glassy carbon. The formate faradaic efficiency with the Pd, Au, Pt and Cu is lower than 25%, while the one with the respective metal amalgams is higher than 50%. Pd amalgam among the tested samples shows the highest formate faradic efficiency and current density. The formate faradaic efficiency is recorded 85% at −2.1 V vs SCE and the formate current density is −6.9 mA cm−2. It is concluded that Pd2Hg5 alloy on the Pd amalgam electrode is an active phase for formate production in the electrochemical CO2 reduction.

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Fabrication of Large Area Ag Gas Diffusion Electrode via Electrodeposition for Electrochemical CO2 Reduction

Coatings ◽

10.3390/coatings10040341 ◽

2020 ◽

Vol 10 (4) ◽

pp. 341

Author(s):

Seonhwa Oh ◽

Hyanjoo Park ◽

Hoyoung Kim ◽

Young Sang Park ◽

Min Gwan Ha ◽

...

Keyword(s):

Co2 Reduction ◽

Gas Diffusion ◽

Gas Diffusion Electrode ◽

Carbon Paper ◽

Membrane Electrode ◽

Co2 Conversion ◽

Large Area ◽

Faradaic Efficiency ◽

Electrochemical Co2 Reduction ◽

Galvanostatic Deposition

For the improvement for the commercialization of electrochemical carbon dioxide (CO2) conversion technology, it is important to develop a large area Ag gas diffusion electrode (GDE), that exhibits a high electrochemical CO2 conversion efficiency and high cell performance in a membrane electrode assembly (MEA)-type CO2 electrolyzer. In this study, the electrodeposition of Ag on a carbon-paper gas diffusion layer was performed to fabricate a large area (25.5 and 136 cm2) Ag GDE for application to an MEA-type CO2 electrolyzer. To achieve uniformity throughout this large area, an optimization of the electrodeposition variables, such as the electrodes system, electrodes arrangement, deposition current and deposition time was performed with respect to the total electrolysis current, CO production current, Faradaic efficiency (FE), and deposition morphology. The optimal conditions, that is, galvanostatic deposition at 0.83 mA/cm2 for 50 min in a horizontal, two-electrode system with a working-counter electrode distance of 4 cm, did ensure a uniform performance throughout the electrode. The position-averaged CO current densities of 2.72 and 2.76 mA/cm2 and FEs of 83.78% (with a variation of 3.25%) and 82.78% (with a variation of 8.68%) were obtained for 25.5 and 136 cm2 Ag GDEs, respectively. The fabricated 136 cm2 Ag GDE was further used in MEA-type CO2 electrolyzers having an active geometric area of 107.44 cm2, giving potential-dependent CO conversion efficiencies of 41.99%–57.75% at Vcell = 2.2–2.6 V.

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An NADH-Inspired Redox Mediator Strategy to Promote Second-Sphere Electron and Proton Transfer for Cooperative Electrochemical CO2 Reduction Catalyzed by Iron Porphyrin

10.26434/chemrxiv.12159207.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Peter T. Smith ◽

Sophia Weng ◽

Christopher Chang

Keyword(s):

Proton Transfer ◽

Co2 Reduction ◽

Iron Porphyrin ◽

Redox Mediators ◽

Reservoir Properties ◽

Proton Reduction ◽

Electrochemical Co2 Reduction ◽

Starting Point ◽

Rate Improvement ◽

Molecular Catalysts

We present a bioinspired strategy for enhancing electrochemical carbon dioxide reduction catalysis by cooperative use of base-metal molecular catalysts with intermolecular second-sphere redox mediators that facilitate both electron and proton transfer. Functional synthetic mimics of the biological redox cofactor NADH, which are electrochemically stable and are capable of mediating both electron and proton transfer, can enhance the activity of an iron porphyrin catalyst for electrochemical reduction of CO2 to CO, achieving a 13-fold rate improvement without altering the intrinsic high selectivity of this catalyst platform for CO2 versus proton reduction. Evaluation of a systematic series of NADH analogs and redox-inactive control additives with varying proton and electron reservoir properties reveals that both electron and proton transfer contribute to the observed catalytic enhancements. This work establishes that second-sphere dual control of electron and proton inventories is a viable design strategy for developing more effective electrocatalysts for CO2 reduction, providing a starting point for broader applications of this approach to other multi-electron, multi-proton transformations.

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