Giron Rodriguez Carlos A, Joensen Bjørt Óladottir, Moss Asger Barkholt, Larrazábal Gastón O, Whelligan Daniel K, Seger Brian, Varcoe John R, Willson Terry R
Surface Physics and Catalysis (SurfCat) Section, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
School of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, U.K.
ACS Sustain Chem Eng. 2023 Jan 18;11(4):1508-1517. doi: 10.1021/acssuschemeng.2c06205. eCollection 2023 Jan 30.
The performance of zero-gap CO electrolysis (COE) is significantly influenced by the membrane's chemical structure and physical properties due to its effects on the local reaction environment and water/ion transport. Radiation-grafted anion-exchange membranes (RG-AEM) have demonstrated high ionic conductivity and durability, making them a promising alternative for COE. These membranes were fabricated using two different thicknesses of ethylene-tetrafluoroethylene polymer substrates (25 and 50 μm) and three different headgroup chemistries: benzyl-trimethylammonium, benzyl--methylpyrrolidinium, and benzyl--methylpiperidinium (MPIP). Our membrane characterization and testing in zero-gap cells over Ag electrocatalysts under commercially relevant conditions showed correlations between the water uptake, ionic conductivity, hydration, and cationic-head groups with the COE efficiency. The thinner 25 μm-based AEM with the MPIP-headgroup (ion-exchange capacities of 2.1 ± 0.1 mmol g) provided balanced in situ test characteristics with lower cell potentials, high CO selectivity, reduced liquid product crossover, and enhanced water management while maintaining stable operation compared to the commercial AEMs. The CO electrolyzer with an MPIP-AEM operated for over 200 h at 150 mA cm with CO selectivities up to 80% and low cell potentials (around 3.1 V) while also demonstrating high conductivities and chemical stability during performance at elevated temperatures (above 60 °C).
零间隙CO电解（COE）的性能会受到膜的化学结构和物理性质的显著影响，因为这些性质会对局部反应环境以及水/离子传输产生作用。辐射接枝阴离子交换膜（RG-AEM）已展现出高离子传导率和耐久性，使其成为COE的一种有前景的替代材料。这些膜是使用两种不同厚度的乙烯-四氟乙烯聚合物基底（25和50μm）以及三种不同的头基化学结构制备而成：苄基三甲基铵、苄基甲基吡咯烷鎓和苄基甲基哌啶鎓（MPIP）。我们在商业相关条件下于Ag电催化剂上的零间隙电池中进行的膜表征和测试表明，水吸收、离子传导率、水合作用以及阳离子头基与COE效率之间存在相关性。与市售AEM相比，基于25μm的、带有MPIP头基（离子交换容量为2.1±0.1 mmol g）的较薄AEM提供了平衡的原位测试特性，具有更低的电池电位、高CO选择性、减少的液体产物渗透以及增强的水管理能力，同时保持稳定运行。带有MPIP-AEM的CO电解槽在150 mA cm下运行超过200小时，CO选择性高达80%，电池电位较低（约3.1 V），同时在高温（60°C以上）运行期间也表现出高传导率和化学稳定性。
