Selective Electroreduction of CO₂ to n‐Propanol in Two‐Step Tandem Catalytic System

Abstract Electrocatalytic reduction of CO₂ (CO₂RR) to high‐energy‐density C₃ fuels like n‐propanol has been widely recognized as one of the core technologies for both renewable energy storage and carbon neutrality. Unfortunately, exceptional catalytic sites that are able to simultaneously implement efficient conversion to C₁ and C₂ products are difficult to design for single electrolyzers, leading to poor activity and selectivity toward n‐propanol. Alternatively, electroreduction of CO (CORR) has shown good performance toward C₃ fuels, but the cost and safety of gas storage hinder its industrialization. Herein, a system consisting of two tandem electrolyzers for converting CO₂ to CO and CO to n‐propanol, respectively, is constructed. Beyond the reported tandem electrodes and one‐pot tandem catalysts, precise voltage control over tandem electrolyzers enables optimizing the conversion of both CO₂RR to CO and CORR to n‐propanol. Significantly, an unprecedented Faradaic efficiency of 15.9% for n‐propanol along with corresponding half‐cell power conversion efficiency of 19.3% is achieved.