Applying Plasmonic Catalyst in CO₂ Electrolyzer for Enhancing Energy Efficiency

We report a CO2 electrolyzer that uses electricity and light together to enhance the energy efficiency. Au nanoparticles (Au NPs) grown on Ag nanowires (Ag NWs) were used as a plasmonic catalyst to fabricate the cathode, forming a conductive porous network that allowed the transfer of gaseous CO2. A conventional three-electrode cell and a two-electrode cell that resembled a zero-gap membrane-electrode assembly (MEA) were compared. We analyzed the dynamics of photogenerated electrons using transient absorption spectroscopy, showing significant decrease in the decay lifetime of the bleaching signals at characteristic plasmonic transition wavelengths when the samples were purged with CO2. This behavior indicates that the electrochemical reduction is likely facilitated by the photoexcited charge carriers on Au NP/Ag NW catalysts. The MEA-like cell demonstrated a marked improvement in the energy efficiency. This work provides a valuable insight into design of energy-efficient CO2 electrolyzer, emphasizing the potential benefits of using light-activated plasmonic catalysts within an MEA-like configuration.