Abarca Jose Antonio, Warmuth Lucas, Rieder Alain, Dutta Abhijit, Vesztergom Soma, Broekmann Peter, Irabien Angel, Díaz-Sainz Guillermo
Departamento de Ingenierías Química y Biomolecular, Universidad de Cantabria, Avenida de los Castros s/n, Santander 39005, Spain.
Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen 76344, Germany.
ACS Catal. 2025 May 9;15(11):8753-8767. doi: 10.1021/acscatal.5c02052. eCollection 2025 Jun 6.
The electrochemical reduction of CO (ERCO) to formate is a promising decarbonization strategy, yet the long-term stability of gas diffusion electrodes (GDEs) remains a major bottleneck for large-scale implementation and technoeconomic viability. This study systematically investigates the role of catalyst layer (CL) composition in enhancing GDE performance and durability, focusing on ionomer selection, catalyst-to-ionomer ratio optimization, and the use of additives (such as PTFE) to tune the CL hydrophobicity. As a catalyst, (BiO)CO is used as an active material thanks to its selectivity toward formate. The impact of the ionomer type is evaluated by comparing , a proton-conducting ionomer, with , an anion-conducting ionomer. While -based GDEs exhibit competitive selectivity toward formate at low ionomer content, with Faradaic efficiencies (FE) around 85%, increasing the ionomer concentration can promote hydrogen evolution reaction (HER), with FEs for H even exceeding 60%, due to worsened catalyst distribution and the clogging of CO pathways to the active catalyst sites. In contrast, -based GDEs effectively suppress HER across all catalyst-to-ionomer ratios, achieving high FEs for formate, in the range of 60-90%. However, even with , excessive ionomer loading leads to pore clogging, limited CO accessibility, and decreased formate production. To further enhance stability, PTFE is introduced as an additive alongside , tuning the hydrophobicity of the CL. By optimizing the amount of PTFE to add, we achieve continuous operation for 24 h, maintaining a high FE for formate (∼85%) and keeping HER below 10%, with formate rates of 8.92 mmol m s and single-pass conversion efficiencies of 5.81%. Stability studies reveal that - and -only GDEs suffer from electrolyte flooding over time, which limits the CO transport and accelerates HER. In contrast, flooding can be prevented on PTFE-modified GDEs, enabling permanent catalyst accessibility and preventing high HER rates. These findings underscore the critical role of CL composition in achieving prolonged GDE stability. By leveraging anion-conducting ionomers and optimizing hydrophobicity, this work provides a pathway toward the scalable deployment of ERCO in formate technology.
将一氧化碳电化学还原（ERCO）为甲酸盐是一种很有前景的脱碳策略，然而气体扩散电极（GDE）的长期稳定性仍然是大规模实施和技术经济可行性的主要瓶颈。本研究系统地研究了催化剂层（CL）组成在提高GDE性能和耐久性方面的作用，重点关注离聚物的选择、催化剂与离聚物比例的优化以及使用添加剂（如聚四氟乙烯）来调节CL的疏水性。作为催化剂，（BiO）CO因其对甲酸盐的选择性而被用作活性材料。通过比较质子传导离聚物和阴离子传导离聚物来评估离聚物类型的影响。虽然基于的GDE在低离聚物含量下对甲酸盐表现出有竞争力的选择性，法拉第效率（FE）约为85%，但增加离聚物浓度会促进析氢反应（HER），由于催化剂分布恶化和通往活性催化剂位点的CO途径堵塞，H的FE甚至超过60%。相比之下，基于的GDE在所有催化剂与离聚物比例下都能有效抑制HER，实现甲酸盐的高FE，范围在60 - 90%。然而，即使使用，过量的离聚物负载也会导致孔堵塞、CO可及性受限以及甲酸盐产量下降。为了进一步提高稳定性，引入聚四氟乙烯作为添加剂与一起调节CL的疏水性。通过优化聚四氟乙烯的添加量，我们实现了24小时连续运行，保持甲酸盐的高FE（约85%）并使HER低于10%，甲酸盐速率为8.92 mmol m s，单程转化效率为5.81%。稳定性研究表明，仅基于和的GDE会随着时间推移遭受电解液淹没，这限制了CO传输并加速了HER。相比之下，在聚四氟乙烯改性的GDE上可以防止淹没，使催化剂能够永久可及并防止高HER速率。这些发现强调了CL组成在实现GDE长期稳定性方面的关键作用。通过利用阴离子传导离聚物并优化疏水性，这项工作为ERCO在甲酸盐技术中的可扩展部署提供了一条途径。
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