Low overpotential and high current CO2 reduction with surface reconstructed Cu foam electrodes
S., Min Yang X., Lu A.-Y., Tseng C.-C., Hedhili M.N., Li L.-J., Huang K.-W.
Nano Energy, volume 27, pp. 121-129, (2016)
CO2 reduction, Cu foam electrode, Surface reconstruction, High current density, Low overpotential
While recent reports have demonstrated that oxide-derived Cu-based electrodes exhibit high selectivity for CO2 reduction at low overpotential, the low catalytic current density (<2 mA/cm2 at −0.45 V vs.
RHE) still largely limits its applications for large-scale fuel
synthesis. Here we report an extremely high current density for CO2
reduction at low overpotential using a Cu foam electrode prepared by
air-oxidation and subsequent electroreduction. Apart from possessing
three-dimensional (3D) open frameworks, the resulting Cu foam electrodes
prepared at higher temperatures exhibit enhanced electrochemically
active surface area and distinct surface structures. In particular, the
Cu foam electrode prepared at 500 °C exhibits an extremely high geometric current density of ~9.4 mA/cm2 in CO2-saturated 0.1 M KHCO3 aqueous solution and achieving ~39% CO and ~23% HCOOH Faradaic efficiencies at −0.45 V vs.
RHE. The high activity and significant selectivity enhancement are
attributable to the formation of abundant grain-boundary supported
active sites and preferable (100) and (111) facets as a result of
reconstruction of Cu surface facets. This work demonstrates that the
structural integration of Cu foam with open 3D frameworks and the
favorable surface structures is a promising strategy to develop an
advanced Cu electrocatalyst that can operate at high current density and
low overpotential for CO2 reduction.
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