Electrochemical Reduction of Carbon Dioxide on Silver Nanostructures 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 silver electrocatalysts derived from a simple, one-step cyclic voltammetry (CV) process by changing scan rates (1–200 mV/s) was demonstrated. Interestingly, larger nanoparticles prepared by slower scan rates (1–5 mV/s) have exhibited the most degree of enhancement for CO₂ reduction to CO product. Compared to untreated silver foil, nanostructured silver electrode has shown an anodic shift of approximately 200 mV in the onset potential of CO partial current density (j_CO), 160 mV reduction of overpotential at j_CO = 10 mA/cm², and increased Faradaic efficiency (F.E.) for CO production especially at lower biased potentials (−0.89–−1.19 V 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.