Tuning Redox Dynamics in Cu‐Based Electrocatalysts: Effect of Secondary Metals

ABSTRACT Electrocatalytic CO 2 reduction reaction (CO 2 RR) facilitates the conversion of CO 2 into oxygenates and hydrocarbons, providing an attractive path for storing energy from renewable energy sources as value‐added products. Cu‐based catalysts exhibit the unique ability to generate energy‐dense C 2+ products at significant rates. Nonetheless, further tailoring of catalysts’ properties is needed to enhance their selectivity. Among other strategies, the utilization of CO‐forming secondary metals and the application of pulsed reaction protocols have been proposed. However, the systematic comparison of the impact of potential pulses on the structure and functionality of bimetallic catalysts has not been attempted so far. Here, we compare the evolution of Cu nanocatalysts, decorated with Ag, Au, Pd, and Zn nanoparticles. By employing operando Quick X‐ray Absorption Spectroscopy combined with a machine learning‐based data analysis approach, we track potential‐dependent (de‐) alloying processes and elucidate the effect of different secondary metals on the redox behavior of Cu. Our study reveals a strong influence of secondary metals on the formation of Cu oxides. Furthermore, a universal behavior in mono‐ and bimetallic Cu nanocubes can be observed regarding the correlation between the amount of Cu(I) species formed under anodic conditions and the resulting ratio of ethanol and ethylene formed during the cathodic pulse.