Researchers from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences and Yanshan University have proposed a strategy for boosting the CO faradaic efficiency in electrocatalytic CO₂ reduction reaction (eCO₂RR), an attractive option to address serious climate concerns and produce value-added chemical feedstock via coupling with renewable energies. The strategy is promising in producing CO via eCO₂RR at ambient conditions. 

The study was published at Advanced Functional Materials on August 30th (DOI: 10.1002/adfm.202307444).  

Among the large variety of products, such as formate, CO, CH₄, C₂H₄, C₂H₅OH, and CH₃OH, converted from eCO₂RR, CO is of particular importance. 

Unfortunately, although the eCO₂RR to CO has the advantage of being carried out at ambient temperature and pressure, it suffers from low faradaic efficiency due to more negative potential than theoretical value, i.e., overpotential, where the hydrogen evolution reaction (HER) is kinetically preferred. 

"The key issue addressing the above-mentioned challenge is to design and develop efficient electrocatalysts that are more favorable for catalyzing eCO₂RR instead of HER," said Prof. YANG Jun from IPE, corresponding author of the study. 

Theoretical calculations validated that the ensemble sites composed of Ag and Pd atoms could promote the eCO₂RR by either weakening the CO adsorption or enhancing the COOH adsorption. Based on this, the researchers reported a strategy to produce AgPd alloy nanoparticles with fine sizes for synergizing the ensemble effect and size leverage, achieving high CO faradaic efficiency of up to 98.9% in eCO₂RR with satisfactory durability. 

"This work highlights the tailoring of active sites via atomic ensembles, which provides a practical method for rationally designing advanced electrocatalysts towards high-efficiency eCO₂RR," said Prof. YANG.