Near-Electrode Concentration Gradients of Bicarbonate and pH within Porous Gas Diffusion Electrode for Optimized Selective CO 2 Electroreduction to C 2+ Products

作者：Yao Tan, Xiqing Wang, Xiangqiong Liao, Qin Chen, Hongmei Li, Kang Liu, Junwei Fu, Min Liu · 发表于：Nano Letters · 年份：2024 · DOI：10.1021/acs.nanolett.4c03116 · 被引用次数：11 · 研究领域：CO2 Reduction Techniques and Catalysts、Ionic liquids properties and applications、Electrochemical Analysis and Applications

With high current density, the intense near-electrode CO 2 reduction reaction (CO 2 RR) will cause the concentration gradients of bicarbonate (HCO 3 – ) and hydroxyl (OH – ) ions, which affect the selectivity of high-value C 2+ products of the CO 2 RR. In this work, we simulated the near-electrode concentration gradients of electrolyte species with different porous Cu-based CLs (catalyst layers) of GDE (gas diffusion electrode) by COMSOL Multiphysics. The higher porosity CL exhibits a better buffer ability of local alkalinity while ensuring a sufficient supply of H + and local CO 2 concentration. Subsequently, the different porosity CLs were prepared by vacuum-thermal evaporation with different evaporation rate. Structural characterizations and liquid permeability tests confirm the role of the porous CL structure in optimizing concentration gradients. As a result, the high-porosity CL (Cu-HP) exhibits a higher C 2+ Faraday efficiency (FE) of ∼79.61% at 500 mA cm –2 under 1 M KHCO 3, far more than the FE C2+ ≈ 38.20% with the low-porosity sample (Cu-LP).