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 (1-200 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 Ag foil, nanostructured Ag 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 j(CO) = 10 mA/cm(2), 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. Xray photoelectron spectroscopy suggests that the enhancement is associated with stable oxygen species incorporated on the nanoparticle Ag surfaces during the CV fabrication process. (C) 2015 Elsevier B.V. All rights reserved.