Water Activity Regulates CO2 Reduction in Gas-Diffusion Electrodes

Reaction Thermodynamics ◽

Current Densities ◽

Reaction Equilibrium

Electrochemical CO2 reduction has recently reached current densities as high as 1 A cm-2, enabled by improving diffusion of CO2 from the gas phase to the electrocatalyst by use of gas-diffusion electrodes (GDEs) and by improving electrolyte ionic conductivity with concentrated hydroxide electrolytes (7 M KOH). Despite such high solute concentrations, the dilute electrolyte assumption is commonly used to evaluate the thermodynamics of the system, specifically reaction equilibrium potential and reaction rate expression. Here we establish a paradigm shift by demonstrating how to properly include the activity of water and solutes and highlighting corrections to associated reaction thermodynamics.

Optimizing Reaction Conditions and Gas Diffusion Electrodes Applied in the CO2 Reduction Reaction to Formate to Reach Current Densities up to 1.8 A cm–2

ACS Sustainable Chemistry & Engineering ◽

10.1021/acssuschemeng.1c00199 ◽

2021 ◽

Author(s):

Armin Löwe ◽

Maximilian Schmidt ◽

Fabian Bienen ◽

Dennis Kopljar ◽

Norbert Wagner ◽

...

Keyword(s):

Co2 Reduction ◽

Gas Diffusion ◽

Reduction Reaction ◽

Reaction Conditions ◽

Current Densities ◽

Co2 Reduction Reaction

CO2 reduction on gas-diffusion electrodes and why catalytic performance must be assessed at commercially-relevant conditions

Energy & Environmental Science ◽

10.1039/c8ee03134g ◽

2019 ◽

Vol 12 (5) ◽

pp. 1442-1453 ◽

Cited By ~ 165

Author(s):

Thomas Burdyny ◽

Wilson A. Smith

Keyword(s):

Local Reaction ◽

Co2 Reduction ◽

Catalytic Performance ◽

Gas Diffusion ◽

High Current ◽

Current Densities ◽

Current Practices

The substantial implications of high current densities on the local reaction environment and design of catalysts for electrochemical CO2 reduction are addressed. The presented perspectives also reflect on current practices within the field and offer new opportunities for both future catalyst and system-focused research efforts.

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 ◽

Cross Sectional ◽

Faradaic Efficiency ◽

Icp Ms ◽

Electrochemical Co2 Reduction ◽

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.

Operando Topography and Mechanical Property Mapping of CO2 Reduction Gas-Diffusion Electrodes Operating at High Current Densities

Journal of The Electrochemical Society ◽

10.1149/1945-7111/abf183 ◽

2021 ◽

Vol 168 (4) ◽

pp. 044505

Author(s):

Nathan T. Nesbitt ◽

Wilson A. Smith

Keyword(s):

Mechanical Property ◽

Co2 Reduction ◽

Gas Diffusion ◽

High Current ◽

Operando Topography and Mechanical Property Mapping of CO2 Reduction Gas-Diffusion Electrodes Operating at High Current Densities

10.26434/chemrxiv.13585184.v1 ◽

2021 ◽

Author(s):

Nathan Nesbitt ◽

Wilson Smith

Keyword(s):

Mechanical Property ◽

Best Practices ◽

Co2 Reduction ◽

Gas Diffusion ◽

High Current ◽

Reactor Operation ◽

Research Article ◽

Depth Analysis ◽

Here, in this research article we develop an electrochemical flow cell for EC-AFM of GDEs for CO2R and provide an in-depth analysis of challenges, best practices, and possible future improvements for the technique. Specifically, we demonstrate continuous operando EC-AFM topography and mechanical property map recording during CO2R reactor operation at 1, 10, and 100 mA cm-2.

Operando Topography and Mechanical Property Mapping of CO2 Reduction Gas-Diffusion Electrodes Operating at High Current Densities

10.26434/chemrxiv.13585184 ◽

2021 ◽

Author(s):

Nathan Nesbitt ◽

Wilson Smith

Keyword(s):

Mechanical Property ◽

Best Practices ◽

Co2 Reduction ◽

Gas Diffusion ◽

High Current ◽

Reactor Operation ◽

Research Article ◽

Depth Analysis ◽

Here, in this research article we develop an electrochemical flow cell for EC-AFM of GDEs for CO2R and provide an in-depth analysis of challenges, best practices, and possible future improvements for the technique. Specifically, we demonstrate continuous operando EC-AFM topography and mechanical property map recording during CO2R reactor operation at 1, 10, and 100 mA cm-2.

Compact and efficient gas diffusion electrodes based on nanoporous alumina membranes for microfuel cells and gas sensors

The Analyst ◽

10.1039/c9an01882d ◽

2020 ◽

Vol 145 (1) ◽

pp. 122-131 ◽

Cited By ~ 1

Author(s):

Wanda V. Fernandez ◽

Rocío T. Tosello ◽

José L. Fernández

Keyword(s):

Response Times ◽

Hydrogen Oxidation ◽

Fast Response ◽

Gas Diffusion ◽

Limiting Current ◽

Nanoporous Alumina ◽

Alumina Membranes ◽

Current Densities ◽

Microfuel Cells

Gas diffusion electrodes based on nanoporous alumina membranes electrocatalyze hydrogen oxidation at high diffusion-limiting current densities with fast response times.