Novel Geometries for In-Flow Electrodeposition Enable More Selective and Stable CO2 Electroreduction Catalysts

To hasten the transition towards carbon neutrality, we look to the promising pathway of industrial-scale CO₂ electroreduction towards profitable chemicals. Large, cheap, uniform electrodes must be reliably produced to implement this technology, preferably through methods already adopted in the industry, such as electroplating.<br/>Most popular approaches for applying metal catalysts in CO₂ electroreduction primarily utilize electrospraying methods. However, electrospraying is more challenging to scale and prone to imperfections in the catalyst deposition process. Nonuniform catalyst deposition is detrimental to CO₂electrolysis, resulting in uneven current density and inconsistent reaction rates across the electrodes, thus creating less efficient systems and reproducibility issues.<br/>Instead, we propose a flow reactor for the uniform electroplating of catalysts onto an electrode and provide a scalable, one-step procedure to synthesize a copper electrode with the C2+ faradaic efficiency similar to the faradaic efficiency achieved using multi-step, resource-intensive methods.<br/>Additionally, while the industry has adopted electrolyzers/flow cells on a small scale, improvements to cell designs must be made for widespread implementation. To address this issue, we use a 3D printable electrolyzer to plate copper onto carbon paper for CO₂ reduction towards ethylene in flow. 3D-printed electrolyzers are cheap, quick to print, and can be customized for more optimized flow field geometry, enabling the development of a wide variety of flow plate geometries to increase electrolyzer efficiency and control over systemic variables.<br/>Here we investigate four different flow plate geometries and analyze their impact on catalyst plating uniformity during electrodeposition of copper via SEM. Simulations of fluid flow through each geometry were conducted using ANSYS FLUENT and validated with benchtop experimentation to determine the optimal specific electrodeposition flow conditions to enable consistent copper plating uniformity.<br/>The impact of copper catalyst uniformity on CO₂ electrolysis efficiency towards ethylene in flow is also explored using a gas diffusion electrode system. By finetuning the process of electrodeposition in flow, the GDE system experienced an enhancement of the selectivity towards specific products and mitigated selectivity loss over time. Achieving these two improvements is an important stepping stone on the way to introduce CO₂ electroreduction on scale.