Electrocatalytic CO₂ reduction is often carried out in a solution electrolyte such as KHCO₃(aq), which allows for ion conduction between electrodes. Therefore, liquid products that form are in a mixture with the dissolved salts, requiring energy-intensive downstream separation. Here, we report continuous electrocatalytic conversion of CO₂ to pure liquid fuel solutions in cells that utilize solid electrolytes, where electrochemically generated cations (such as H⁺) and anions (such as HCOO⁻) are combined to form pure product solutions without mixing with other ions. Using a HCOOH-selective (Faradaic efficiencies > 90%) and easily scaled Bi catalyst at the cathode, we demonstrate production of pure HCOOH solutions with concentrations up to 12 M. We also show 100 h continuous and stable generation of 0.1 M HCOOH with negligible degradation in selectivity and activity. Production of other electrolyte-free C₂₊ liquid oxygenate solutions, including acetic acid, ethanol and n-propanol, are also demonstrated using a Cu catalyst. Finally, we show that our CO₂ reduction cell with solid electrolytes can be modified to suit other, more complex practical applications.

电催化CO ₂还原通常在诸如KHCO ₃（aq）的溶液电解质中进行，这允许电极之间的离子传导。因此，形成的液体产物与溶解的盐混合在一起，需要进行能量密集的下游分离。这里，我们报告CO的连续电催化转化₂在利用固体电解质电池，以纯液体燃料的解决方案，其中电化学产生阳离子（例如H ⁺）和阴离子（如HCOO ^-）合并后可形成纯净的产品溶液，而无需与其他离子混合。在阴极上使用选择性HCOOH（法拉第​​效率> 90％）和易于缩放的Bi催化剂，我们证明了浓度高达12 M的纯HCOOH溶液的生产。我们还显示了100 h连续，稳定地产生0.1 M HCOOH且可忽略不计选择性和活性下降。还证明了使用Cu催化剂生产其他无电解质的C ₂₊液态含氧溶液，包括乙酸，乙醇和正丙醇。最后，我们表明可以对带有固体电解质的CO ₂还原电池进行改造，以适应其他更复杂的实际应用。