Alkali hydroxide systems capture CO₂ as carbonate; however, generating a pure CO₂ stream requires significant energy input, typically from thermal cycling to 900°C. What is more, the subsequent valorization of gas-phase CO₂ into products presents additional energy requirements and system complexities, including managing the formation of (bi)carbonate in an electrolyte and separating unreacted CO₂ downstream. Here, we report the direct electrochemical conversion of CO₂, captured in the form of carbonate, into multicarbon (C₂₊) products. Using an interposer and a Cu/CoPc-CNTs electrocatalyst, we achieve 47% C₂₊ Faradaic efficiency at 300 mA cm⁻² and a full cell voltage of 4.1 V. We report 56 wt % of C₂H₄ and no detectable C₁ gas in the product gas stream: CO, CH₄, and CO₂ combined total below 0.9 wt % (0.1 vol %). This approach obviates the need for energy to regenerate lost CO₂, an issue seen in prior CO₂-to-C₂₊ reports.

碱金属氢氧化物系统将 CO ₂捕获为碳酸盐；然而，产生纯 CO ₂流需要大量能量输入，通常从热循环到 900°C。更重要的是，随后将气相 CO ₂稳定化为产品会带来额外的能源需求和系统复杂性，包括管理电解液中碳酸氢盐的形成以及在下游分离未反应的 CO ₂。在这里，我们报告了以碳酸盐形式捕获的CO ₂直接电化学转化为多碳 (C ₂₊ ) 产物。使用中介层和 Cu/CoPc-CNTs 电催化剂，我们在 300 mA cm ^{-2下实现了 47% C} ₂₊法拉第效率和 4.1 V 的全电池电压。我们报告了 56 wt% 的 C ₂ H ₄并且在产品气流中没有检测到 C _{1气体：CO、CH 4}和 CO _{2 的}总和低于 0.9 wt % (0.1 vol %) . 这种方法避免了再生损失的 CO ₂所需的能量，这是之前 CO ₂ -to-C ₂₊报告中出现的一个问题。