Rapid fabrication of phase-separated Cu-Zn particles though “droplet-to-particle” method and their performance in CO₂ electrocatalysis

The electrochemical reduction of CO₂ into valuable chemicals presents a promising CO₂ mitigation technology. However, rapid preparation of efficient and stable catalysts remains a challenge. The “droplet-to-particle” method allows for the rapid synthesis of catalysts with precise elemental composition control. In this study, Cu-Zn bimetallic nanoparticle catalysts with phase-separated structures and varying elemental compositions were prepared using this method. The formation process of the catalysts was analyzed, and their performance in CO₂ electroreduction was investigated. Aerosol dynamics simulation revealed that the formation process of the catalyst particles involves the transformation from a single droplet to a single particle. TEM observations showed hollow regions in the center of the catalyst particles, attributed to the rapid evaporation of the droplets, which led to the formation of hollow particles in some cases. This also explains why some catalyst particles had a larger actual diameter than the theoretical solid particle size. By calculating the residence time of droplets in the reactor, it was found that the transformation from droplets to particles occurred within approximately 4.37 s, indicating the rapid formation of catalyst particles. On the other hand, electrochemical experiments demonstrated that when the Cu/Zn molar ratio was 2:8, the faraday efficiency (FE) of CO reached up to 73 % at −1.1 V vs. RHE, with stable performance over 8 h of operation. Density functional theory (DFT) calculations indicated that the introduction of Zn lowered the energy barrier for the rate-determining step of *COOH formation, promoting the generation of CO. This study provides an in-depth investigation into the “droplet-to-particle” catalyst synthesis process, which is characterized by simplicity, rapidity, ease of control, and cost-effectiveness. These features offer an effective strategy for the industrial application of CO₂ electroreduction.