Electrochemical reduction of CO₂ to liquid fuels is a promising route to a carbon-neutral, energy-dense storage of intermittent renewable electricity. However, electrocatalysts generally suffer from high overpotential and poor selectivity for multi-carbon products such as ethanol, and efforts to enhance such catalysts are limited by scaling relations which inhibit a simultaneous optimization of each elementary electrochemical step. In this work, the multistep proton-coupled electron-transfer reaction for the conversion of CO₂ to C₂H₅OH was strategically divided into two independently optimized steps in a sequential cascade reaction using heterogeneous electrocatalysts to convert CO₂ to CO and CO to C₂H₅OH within a single integrated electrochemical system. The exclusion of CO₂ reactant from the second-stage electrolyzer was observed to be critical for maintaining appreciable ethanol selectivity. The cascade system produced C₂H₅OH at an overall faradaic efficiency of 11.0% at an average applied potential of −0.52 V vs. RHE, making it highly competitive with known single-step electrocatalysts for ethanol production from CO₂. This performance was despite limited conversion of the intermediate CO between cascade steps (∼6.4%), and reactor design improvements to enhance the conversion could lead to significantly enhanced ethanol production performance.

用电化学方法将CO ₂还原为液体燃料是间歇性可再生电力实现碳中和，能量密集存储的有前途的途径。然而，电催化剂通常遭受对多碳产物例如乙醇的高过电势和差的选择性的困扰，并且通过比例关系限制了增强此类催化剂的努力，所述比例关系阻碍了每个基本电化学步骤的同时优化。在这项工作中，使用异质电催化剂将CO ₂转化为CO和将CO转化为CO的过程中，将CO ₂转化为C ₂ H ₅ OH的多步质子偶联电子转移反应被策略性地分为两个独立优化的步骤。C在单个集成电化学系统中的₂ H ₅ OH。观察到从第二级电解器中排除CO ₂反应物对于维持可观的乙醇选择性至关重要。该级联体系产生的C ₂ H ₅ OH总法拉第效率为11.0％，相对于RHE的平均施加电势为-0.52 V，使其与已知的单步电催化剂在从CO ₂制备乙醇方面具有很高的竞争力。尽管中间CO在级联步骤之间的转化率有限（〜6.4％），但该性能仍得到改善，并且为提高转化率而进行的反应器设计改进可能导致乙醇生产性能显着提高。