Studies on the electrochemical reduction of CO2 at metallic electrodes have suggested that the adsorption of hydrogen species is structure-sensitive and surface roughening is likely to introduce defects favorable for reaction of adsorbed hydrogen atoms, which is one of the principal steps involved in CO2reduction in protic media. To further gauge this effect, copper foam electrodes on copper substrates were prepared by a simple electrodeposition process following reported literature methods.Electrolysis was performed in a typical H-cell under potentiostatic conditions. The microporous foams were mechanically stable such that the microstructure was intact during preparation, handling and electrolysis. Fig 1 plots the faradaic efficiency of formate obtained from the reduction of CO2at a bare copper electrode and the copper foam electrode. Faradaic efficiencies for HCOOH at the electropolished planar electrode were found to be similar to that reported recently by Jaramillo et al. The corresponding efficiencies for the copper foam electrode were found to be higher at all potentials with a maximum efficiency of 37% at -1.5V for HCOOH.The hierarchical porous architecture with high surface area and pore volume could be beneficial for the unimpeded mobility of reactants and products contributing to the observed enhancement in efficiency; viewed as being more physical than chemical catalysis. The 3D structure of the foam allows for superior interaction between the reactant, electrode and electrons in three-dimensional space instead of being confined to a two-dimensional planar electrode.

Electrochemical reduction of CO2 on highly porous copper foam electrodes

247th National Meeting (2014)

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