Bicarbonate electrolyzers (BCEs) offer a promising approach to reducing the energy cost of CO₂ reduction by integrating upstream carbon capture and downstream electrochemical utilization. However, the faradaic efficiency of CO₂ electrolysis in BCEs has been limited by insufficient activated CO₂ on the catalyst surface. We report a hierarchical design strategy combining molecular and system-level innovations to ensure that there is sufficient activated CO₂ on the catalyst in BCEs. At the molecular scale, we introduce a single-atom catalyst CoPc@CNT with strong CO₂ adsorption to prevent CO₂ desorption from the catalyst surface. Systemically, a cathodic electrolyte cross-flow strategy further enhances CO₂ mass transfer. This approach achieves a faradaic efficiency exceeding 96.2% for CO at 50–300 mA cm⁻², with a 36.0% and 35.3% reduction in overall energy cost compared with conventional BCEs and CO₂ gas-fed electrolyzers, respectively. This innovative strategy represents a significant advancement in low-energy-consumption exhaust conversion technologies for carbon neutrality.

碳酸氢盐电解槽（BCE）通过整合上游碳捕获和下游电化学利用，提供了一种有前途的方法来降低CO ₂还原的能源成本。然而，BCE中CO ₂电解的法拉第效率受到催化剂表面活化CO ₂不足的限制。我们报告了一种结合分子和系统级创新的分层设计策略，以确保BCE 中的催化剂上有足够的活化 CO ₂ 。在分子尺度上，我们引入了具有强CO ₂吸附作用的单原子催化剂CoPc@CNT，以防止CO ₂从催化剂表面解吸。系统地，阴极电解液错流策略进一步增强了CO ₂传质。该方法在 50–300 mA cm ^-2下实现了超过 96.2% 的 CO 法拉第效率，与传统 BCE 和 CO ₂气体供给电解槽相比，总体能源成本分别降低了 36.0% 和 35.3%。这一创新战略代表了实现碳中和的低能耗废气转化技术的重大进步。