Commercialization of emerging power-to-X conversion technologies requires efficient integration and recovery of heat and waste within existing chemical plants. The electrochemical reduction of CO₂ fits such a scope, yet current research largely neglects the prospect of elevated temperature operation, which is likely to occur due to Joule heating and cooling constraints. Here, we set out to investigate the performance of liquid-fed CO₂ electrolyzers at temperatures of up to 85 °C─a threshold that exacerbates commonly met stability issues and leads to electrolyzer failure. To prevent the latter, our study first explores the interrelationships between elevated temperature operation, evaporation, gas solubility, electro-wetting, and how they affect performance. At 25 °C, unity selectivity to formate is demonstrated over the course of 24 h. However, at 85 °C, we show that fine optimization of differential pressure (28–40 mbar) has to be carried out to stabilize performance. Ultimately, a faradaic efficiency of 64% could be maintained after 24 h of electrolysis at −100 mA cm^–2─a 68% improvement relative to the nonoptimized system. The substrate-dependent rate of performance decline at 85 °C, which is not distinguishable at ambient temperatures, underscores the necessity for a tailored system and differential pressure control for CO₂ electrolysis at elevated temperatures.

中文翻译：

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气体扩散电极两端的压差控制高温下 CO2 电解还原液体电解槽的效率


新兴电力到 X 转换技术的商业化需要在现有化工厂内有效整合和回收热量和废物。 CO ₂ 的电化学还原符合这样的范围，但目前的研究很大程度上忽略了高温操作的前景，这可能由于焦耳加热和冷却的限制而发生。在这里，我们着手研究液体馈送 CO ₂ 电解槽在高达 85 °C 的温度下的性能——这个阈值会加剧常见的稳定性问题并导致电解槽故障。为了防止后者，我们的研究首先探讨了高温操作、蒸发、气体溶解度、电润湿之间的相互关系以及它们如何影响性能。在 25 °C 下，在 24 小时内证明了对甲酸盐的统一选择性。然而，在 85 °C 时，我们表明必须对压差（28-40 mbar）进行精细优化才能稳定性能。最终，在 -100 mA cm ^–2 下电解 24 小时后，法拉第效率可保持为 64%，相对于非优化系统提高了 68%。 85 °C 时与底物相关的性能下降率在环境温度下无法区分，这强调了在高温下对 CO ₂ 电解进行定制系统和压差控制的必要性。