Aqueous CO₂ Reduction at Very Low Overpotential on Oxide-Derived Au Nanoparticles

Abstract

Carbon dioxide reduction is an essential component of many prospective technologies for the renewable synthesis of carbon-containing fuels. Known catalysts for this reaction generally suffer from low energetic efficiency, poor product selectivity, and rapid deactivation. We show that the reduction of thick Au oxide films results in the formation of Au nanoparticles ("oxide-derived Au") that exhibit highly selective CO(2) reduction to CO in water at overpotentials as low as 140 mV and retain their activity for at least 8 h. Under identical conditions, polycrystalline Au electrodes and several other nanostructured Au electrodes prepared via alternative methods require at least 200 mV of additional overpotential to attain comparable CO(2) reduction activity and rapidly lose their activity. Electrokinetic studies indicate that the improved catalysis is linked to dramatically increased stabilization of the CO(2)(•-) intermediate on the surfaces of the oxide-derived Au electrodes.

CO2 Reduction: From the Electrochemical to Photochemical Approach

“…d) Cross‐sectional SEM image and e) high‐magnification TEM image of oxide‐derived Au NPs; f) Faradaic efficiency for CO and formate on oxide‐derived Au NPs in 0.5 m NaHCO 3 . Reproduced with permission 65. Copyright 2012, American Chemical Society.…”

“…Kanan and co‐workers prepared oxide‐derived Au by simply applying a periodic square‐wave potential routine on Au electrodes and then electrochemically reducing thick Au oxide films (Figure 6d–f) 65. It was suggested that unique metastable structures were resulted from the reduction of the oxide film.…”

“…This surface oxide layer may not be fully reduced even during CO 2 RR electrocatalysis, and therefore would greatly influence the electrochemical process. In order to elucidate the possible effect of the surface oxide layer, Kanan and co‐workers compared the activity of an Sn electrode with native SnO x layer and an electrode etched to expose metallic Sn 0 surface ( Figure 8 a–c) 65. The latter exhibited higher overall current densities but almost exclusively H 2 over the entire potentials range examined.…”

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

“…A single-step electrochemical process that can directly convert CO 2 to methane under conditions of ambient pressure and temperature may represent an attractive alternative. Of the metals explored as catalysts for electrochemical CO 2 reduction,(8) the most active and selective identified to date are gold, silver, and bismuth, (9)(10)(11)(12)(13)(14) which produce CO as their terminal product. Copper is attractive in comparison, as it produces more reduced hydrocarbon products.…”

Liquid Hydrocarbon Production from CO2: Recent Development in Metal‐Based Electrocatalysis

“…It was shown that the surface chemicalc omposition of the Sn foil plays ac rucial role in dictating the conversion of CO 2 into HCOO À . [113] When the native oxide layer in Sn foil was etchedo ut by using concentrated acid, the subsequent electrode demonstrated quite low FE HCOO À compared to the pristine Sn foil (containing native oxide layer). This finding highlighted the requirement of ah eterojunction (interface) between the different oxidation states of Sn for CO 2 RR to HCOO À .T his understanding was also invoked with novel nanostructures such as heat-treatedS nd endrite, which displayed a7 1.6 %F E HCOO À at an applied potential of À1.36 Vi nc omparison with the untreated Sn dendrite, which only exhibited 57 %F E HCOO À at the same potential.…”