Capture and electroreduction of CO₂ using highly efficient bimetallic Pd–Ag aerogels paired with carbon nanotubes

The rational design of efficient catalysts for electrochemical CO₂ reduction is a critical step towards achieving industry-ready electrolyzer systems. Noble metal aerogels have emerged as state-of-the-art catalysts that play a crucial role in several applications. Here, we report bimetallic Pd_xAg_y aerogels that have been optimized by modulating the Pd/Ag ratio for the capture and selective electroreduction of CO₂. Pd_0.67Ag_0.33 exhibited the greatest ability to reduce CO₂ to CO with faradaic efficiency (FE): 84% and current density (j): −23 mA cm⁻² at −0.8 V vs. RHE in 0.1 M NaHCO₃. Using a carbon nanotube solid support (Pd_0.67Ag_0.33/CNT), we could further enhance the FE to 91% with a higher current density of −38 mA cm⁻² at lower overpotential (−0.7 V vs. RHE). This remarkable catalytic activity is higher than that of monometallic Pd (FE: 43%, j: −3.4 mA cm⁻²) and Ag (FE: 68%, j: −2.6 mA cm⁻²) aerogels at −0.8 V vs. RHE. Using bimetallic aerogels provides an effective strategy that could inspire the design of new catalysts for a variety of applications.