Enhancement in carbon dioxide activity and stability on nanostructured silver electrode and the role of oxygen

Current energy production habits deplete fossil fuels and accumulate atmospheric CO₂, which contribute to the global climate change. Electrochemical fuel production via CO₂ reduction reaction is an idealistic yet an achievable process that mitigates CO₂ emissions and simultaneously satisfies energy demands. Here, the enhancement of CO₂ reduction activity and stability on size-controlled particulate Ag electrocatalysts derived from a simple, one-step cyclic voltammetry (CV) process by changing scan rates (1-200mV/s) was demonstrated. Interestingly, larger nanoparticles prepared by slower scan rates (1-5mV/s) have exhibited the most degree of enhancement for CO₂ reduction to CO product. Compared to untreated Ag foil, nanostructured Ag electrode has shown an anodic shift of approximately 200mV in the onset potential of CO partial current density (j_CO), 160mV reduction of overpotential at j_CO=10mA/cm², and increased Faradaic efficiency (F.E.) for CO production especially at lower biased potentials (-0.89 to -1.19V vs. RHE). Stability tests have demonstrated a drastic improvement in maintaining CO F.E. X-ray photoelectron spectroscopy suggests that the enhancement is associated with stable oxygen species incorporated on the nanoparticle Ag surfaces during the CV fabrication process.