CO₂ electrolyzers have progressed rapidly in energy efficiency and catalyst selectivity toward valuable chemical feedstocks and fuels, such as syngas, ethylene, ethanol, and methane. However, each component within these complex systems influences the overall performance, and the further advances needed to realize commercialization will require an approach that considers the whole process, with the electrochemical cell at the center. Beyond the cell boundaries, the electrolyzer must integrate with upstream CO₂ feeds and downstream separation processes in a way that minimizes overall product energy intensity and presents viable use cases. Here we begin by describing upstream CO₂ sources, their energy intensities, and impurities. We then focus on the cell, the most common CO₂ electrolyzer system architectures, and each component within these systems. We evaluate the energy savings and the feasibility of alternative approaches including integration with CO₂ capture, direct conversion of flue gas and two-step conversion via carbon monoxide. We evaluate pathways that minimize downstream separations and produce concentrated streams compatible with existing sectors. Applying this comprehensive upstream-to-downstream approach, we highlight the most promising routes, and outlook, for electrochemical CO₂ reduction.

中文翻译：

---

二氧化碳电解槽

CO ₂电解槽在能源效率和催化剂对合成气、乙烯、乙醇和甲烷等有价值的化学原料和燃料的选择性方面取得了快速进展。然而，这些复杂系统中的每个组件都会影响整体性能，实现商业化所需的进一步进步将需要一种考虑整个过程的方法，以电化学电池为中心。除了电池边界之外，电解槽必须与上游 CO ₂进料和下游分离过程集成，以最大限度地降低总体产品能源强度并提供可行的用例。在这里，我们首先描述上游CO ₂来源、其能量强度和杂质。然后我们重点关注电池、最常见的 CO ₂电解槽系统架构以及这些系统中的每个组件。我们评估了节能效果和替代方法的可行性，包括与 CO ₂捕获集成、烟气直接转化和通过一氧化碳进行两步转化。我们评估最大限度地减少下游分离并产生与现有部门兼容的浓缩流的途径。应用这种全面的上游到下游方法，我们重点介绍了电化学 CO ₂减排最有前途的路线和前景。