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首页> 外文期刊>ACS applied materials & interfaces >Analysis of Mass Flows and Membrane Cross-over in CO2 Reduction at High Current Densities in an MEA-Type Electrolyzer
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Analysis of Mass Flows and Membrane Cross-over in CO2 Reduction at High Current Densities in an MEA-Type Electrolyzer

机译：在MEA型电解槽中的高电流密度下CO2减少的质量流量和膜跨的分析

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Cell designs that integrate membrane-electrode assemblies (MEAs) with highly selective catalysts are a promising route to reduce ohmic losses and achieve high energy efficiency in CO_(2) reduction at industrially relevant current densities. In this work, porous silver filtration membranes are demonstrated as simple and efficient gas-diffusion electrodes for CO_(2) reduction to CO at high current densities in an MEA-type device. A partial current density for CO of up to ca. 200 mA cm~(–2) was achieved at a cell voltage of ca. 3.3 V, in tandem with minimal H_(2) production. However, the analysis of cathodic and anodic outlet streams revealed that CO_(2) cross-over across the anion-exchange membranes, mostly in the form of CO_(3)~(2–) but partially as HCOO~(–) generated over the cathode, actually exceeds the amount of CO_(2) converted to the target product, resulting in a poor utilization of the reactant and in the early onset of mass transfer limitations. In addition, CO_(2) cross-over leads to a nonstoichiometric decrease of the outlet flow rate from the cathodic compartment. This effect can lead to a substantial overestimation of catalytic performance if the inlet flow rate of CO_(2) is used as reference for calculating partial current densities and Faradaic efficiencies. The results of this work highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance of CO_(2) reduction devices at high current densities, and inform future efforts aimed at mitigating membrane cross-over in MEA-type electrolyzers for CO_(2) reduction.
机译：用高选择性催化剂整合膜 - 电极组件（MEA）的细胞设计是有望的途径，以减少欧姆损耗，并在工业相关的电流密度降低CO_（2）降低中的高能量效率。在这项工作中，多孔银过滤膜被证明是用于MEA型装置中的高电流密度的CO_（2）还原的简单且有效的气体扩散电极。达到CA的CO的部分电流密度。在CA的电池电压下实现200mA cm〜（-2）。 3.3 V，串联，最小H_（2）生产。然而，阴极和阳极出口流的分析表明，CO_（2）跨越阴离子交换膜，主要以CO_（3）〜（2-）的形式，但部分地为HCOO〜（ - ）产生阴极实际上超过转化为靶产物的CO_（2）的量，导致反应物的利用率差，并且在早期发作的传质限制。另外，CO_（2）跨越导致来自阴极室的出口流速的非计量减小。如果使用CO_（2）的入口流速作为计算部分电流密度和游览效率，则这种效果可以导致催化性能的显着高估。除了传统的活动和选择性的传统测量外，这项工作的结果突出了进行碳平衡的重要性，以充分评估高电流密度的CO_（2）减少装置的性能，并告知未来旨在减轻膜的努力交叉在MEA型电解槽中用于CO_（2）减少。

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