ICP-MS Assisted EDX Tomography: A Robust Method for Studying Electrolyte Penetration Phenomena in Gas Diffusion Electrodes Applied to CO Electrolysis.

A carbon paper-based gas diffusion electrode (GDE) is used with a bismuth(III) subcarbonate active catalyst phase for the electrochemical reduction of CO in a gas/electrolyte flow-by configuration electrolyser at high current density. It is demonstrated that in this configuration, the gas and catholyte phases recombine to form KCO/KHCO precipitates to an extent that after electrolyses, vast amount of K ions is found by EDX mapping in the entire GDE structure. The fact that the entirety of the GDE gets wetted during electrolysis should, however, not be interpreted as a sign of flooding of the catalyst layer, since electrolyte perspiring through the GDE can largely be removed with the outflow gas, and the efficiency of electrolysis (toward the selective production of formate) can thus be maintained high for several hours.

Cracks as Efficient Tools to Mitigate Flooding in Gas Diffusion Electrodes Used for the Electrochemical Reduction of Carbon Dioxide.

The advantage of employing gas diffusion electrodes (GDEs) in carbon dioxide reduction electrolyzers is that they allow CO to reach the catalyst in gaseous state, enabling current densities that are orders of magnitude larger than what is achievable in standard H-type cells. The gain in the reaction rate comes, however, at the cost of stability issues related to flooding that occurs when excess electrolyte permeates the micropores of the GDE, effectively blocking the access of CO to the catalyst. For electrolyzers operated with alkaline electrolytes, flooding leaves clear traces within the GDE in the form of precipitated potassium (hydrogen)carbonates.

Insights from and Identical Location (IL) Techniques on the Activation of Electrocatalysts for the Conversion of CO₂: A Mini-Review.

In this mini-review we compare two prototypical metal foam electrocatalysts applied to the transformation of CO₂ into value-added products ( alcohols on Cu foams and formate on Bi foams). A substantial improvement in the catalyst performance is typically achieved through thermal annealing of the as-deposited foam materials, followed by the electro-reduction of the pre-formed oxidic precursors prior or during the actual CO₂ electrolysis. Utilizing highly insightful and sensitive complementary analytical techniques (XAS, XRD, and Raman spectroscopy) we demonstrate that this catalyst pre-activation process is entirely accomplished in case of the oxidized Cu foams prior to the formation of hydrocarbons and alcohols from the CO₂.

Suppression of the Hydrogen Evolution Reaction Is the Key: Selective Electrosynthesis of Formate from CO over Porous InCu Catalysts.

Direct electrosynthesis of formate through CO electroreduction (denoted CORR) is currently attracting great attention because formate is a highly valuable commodity chemical that is already used in a wide range of applications (e.g., formic acid fuel cells, tanning, rubber production, preservatives, and antibacterial agents).