Investigation of Phase‐Pure Paramelaconite Cu 4 O 3 as an Efficient Catalyst for CO 2 RR and CORR

In an effort to further sustainable production of platform chemicals, a phase‐pure paramelaconite (Cu 4 O 3 ) is presented and investigated as an electrocatalyst for CO 2 and CO electroreduction. The paramelaconite's catalytic performance is evaluated at current densities relevant for eventual industrial application (−400 mA/cm 2 ), by utilizing a flow cell equipped with a Cu 4 O 3 ‐coated gas diffusion electrode. The material exhibits promising performance at such conditions, with Faradaic efficiencies for C 2+ products reaching 65% and 83% for CO 2 RR and CORR, respectively. Long‐term operation also reveals no material‐related degradation of performance for >100 h. Furthermore, lattice characterization and introduction of guest elements enable deeper insights into the binding of intermediates to the catalytically active spots as well as other parameters important for efficient C─C coupling. Utilizing these findings accordingly results in a paramelaconite‐like Ag 2 Cu 2 O 3 reaching Faradaic efficiency of 93% for C 2+ products in CORR.