Al‐Rich Cu/CuOx Catalyst in a CO2‐Reduction Tandem Electrolyzer with CO‐Enriched Gas Feed for Enhanced C2+‐Products Selectivity

Abstract Electrochemical CO2 conversion is an important strategy to produce high‐value carbon‐containing molecules, such as ethylene and ethanol. Despite huge progress in recent years concerning CO2 reduction catalyst development with increased selectivity, high selectivity for C2+ products at high current densities is still a challenge. We report the development and optimization of a new surface Al‐rich Cu/CuOx catalyst with high selectivity for C2+‐products at high current densities of up to −800 mA cm−2. We integrated the corresponding catalyst‐modified gas‐diffusion electrode into a second flow‐through electrolyzer, which was connected to a first flow‐through electrolyzer comprising a highly CO‐selective Ni−Cu dual‐atom N‐doped carbon catalyst. The enrichment of the CO2 stream with CO generated at a current density of −400 mA cm−2 in the first electrolyzer increased the production rate of ethanol formation at the Al‐rich Cu/CuOx catalyst at a current density of −300 mA cm−2 by 28 %, while maintaining the production rate of ethylene. Thereby, the overall yield of C2+‐products obtained by CO2 reduction was significantly increased.