Effects of composition of the micro porous layer and the substrate on performance in the electrochemical reduction of CO2 to CO

Abstract

With the development of better catalysts, mass transport limitations are becoming a challenge to high throughput electrochemical reduction of CO 2 to CO. In contrast to optimization of electrodes for fuel cells, optimization of gas diffusion electrodes (GDE)consisting of a carbon fiber substrate (CFS), a micro porous layer (MPL), and a catalyst layer (CL)for CO 2 reduction has not received a lot of attention. Here, we studied the effect of the MPL and CFS composition on cathode performance in electroreduction of CO 2 to CO. In a flow reactor, optimized GDEs exhibited a higher partial current density for CO production than Sigracet 35BC, a commercially available GDE. By performing electrochemical impedance spectroscopy in a CO 2 flow reactor we determined that a loading of 20 wt% PTFE in the MPL resulted in the best performance. We also investigated the influence of the thickness and wet proof level of CFS with two different feeds, 100% CO 2 and the mixture of 50% CO 2 and N 2 , determining that thinner and lower wet proofing of the CFS yields better cathode performance than when using a thicker and higher wet proof level of CFS.

Durable Cathodes and Electrolyzers for the Efficient Aqueous Electrochemical Reduction of CO2

“…To combat electrode wetting and dissolution, our group worked on optimizing the composition of the MPL in a carbon‐based GDE . We found that 20 wt % PTFE in the MPL provided the greatest level of hydrophobicity without sacrificing activity to increased contact resistance.…”

Metal–Nitrogen–Carbon Electrocatalysts for CO2 Reduction towards Syngas Generation

“…The MPL thickness also impacts the linear gas‐diffusion resistance. Kim et al . found that a 15 μm MPL with 20 wt % PTFE is optimal for CO 2 →CO reduction on Ag NPs in a GDE configuration.…”

“…found that a 15 μm MPL with 20 wt % PTFE is optimal for CO 2 →CO reduction on Ag NPs in a GDE configuration. A PTFE loading of 4.5–10 wt % in the MPL induces insufficient hydrophobicity and electrode flooding, which 1) decrease the diffusion rate of CO 2 in the CL and 2) favor the HER . Increasing the PTFE content beyond 20 wt % leads to 1) increased charge‐transfer resistance and 2) a decrease in porosity .…”

“…A PTFE loading of 4.5–10 wt % in the MPL induces insufficient hydrophobicity and electrode flooding, which 1) decrease the diffusion rate of CO 2 in the CL and 2) favor the HER . Increasing the PTFE content beyond 20 wt % leads to 1) increased charge‐transfer resistance and 2) a decrease in porosity . Likewise, the CFS benefits by being thin and having only the required content of PTFE to keep the gas and liquid phases separated.…”

Alkalinity Initiated Decomposition of Mediating Imidazolium Ions in High Current Density CO2 Electrolysis

“…The stabilities of the electrolytes containing imidazolium cations were not questioned in these articles—this is where our work comes into the game. Keeping in mind that high current densities have been discussed in detail for aqueous electrolytes without ILs . Thermal degradations of imidazolium ionic liquids have also been studied previously …”