An integrated carbonized wood-based gas-diffusion electrode for high-current-density CO electrosynthesis in flow cells

Abstract

A high-current-density CO₂ reduction reaction (CO₂RR) can be realized in flow cells and membrane electrode assemblies (MEAs) based on the use of gas-diffusion electrodes (GDEs). However, transitional GDEs based on powdery electrocatalysts are usually fabricated using a laborious slurry-based process that involves the use of binders and additives, leading to insufficient activity and stability. In this work, an integrated GDE is developed by employing carbonized wood as a conductive and porous host for reconstructed Ag nanoparticles (Ag@CW-ER). The porous carbon matrix with an abundance of open, aligned microchannels facilitates CO₂ diffusion and electrolyte transportation. The uniformly embedded reconstructed Ag nanoparticles provide numerous active sites that enhance CO₂ adsorption and activation during CO₂ electroreduction. When tested in H-type cells, it offers a high faradaic efficiency (FE_CO) of 88.6% for CO production at −0.97 V vs. the reversible hydrogen electrode (RHE) with a high partial current density (j_CO) of −22.6 mA cm⁻². Most notably, after a simple hydrophobic treatment, the Ag@CW-ER electrode can be directly used as an integrated GDE with well-established and stable three-phase interfaces in the flow cells, achieving a j_CO of −186.7 mA cm⁻² at −1.31 V vs. RHE with excellent stability for 8 h. This work offers an effective strategy towards the rational design of carbon-based integrated GDEs for sustainable CO₂ electroreduction at a large scale.