Electrochemical CO2 Conversion Using Skeleton (Sponge) Type of Cu Catalysts

4 years ago

Electrochemical CO2 Conversion Using Skeleton (Sponge) Type of Cu Catalysts

Motiar Rahaman, Peter Broekmann, Alberto Zanetti, Miklos Mohos, Abhijit Dutta

Highly porous 3D Cu skeletons (sponges) modified by electropolishing, thermal annealing, and foam electrodeposition have been studied as catalysts for the electrochemical conversion of CO₂ with a particular emphasis on C₂ products formation. These catalyst materials appear to be promising for future applications where gaseous CO₂ reactants can be transported through the 3D catalyst thereby tuning the mean residence time of reaction intermediates inside the catalyst, which crucially influences the final product distribution. In particular, the annealed skeleton (300 °C, 12 h) and the one modified by Cu foam electrodeposition show profound activities toward C₂ product formation (C₂H₄, C₂H₆) with faradaic efficiencies reaching FE_C₂ = 32.3% (annealed skeleton sample, −1.1 V vs RHE) and FE_C₂ = 29.1% (electrodeposited sample, −1.1 V vs RHE), whereas the electropolished Cu skeleton remains largely inactive for both the C₁ and the C₂ pathway of hydrocarbon formation. This effect is discussed on the basis of residual impurities that are left behind from the investment casting approach on which the fabrication of these Cu skeleton support materials is based. In addition, a higher FE_C₂H₄/FE_C₂H₆ ratio is observed for the annealed Cu skeleton as compared to the electrodeposited Cu foam. Such a switching in the C₂ product distribution (FE_C₂H₄/FE_C₂H₆ ratio) is discussed on the basis of particular morphological effects (residence time of intermediates inside the catalyst) related to the three-dimensional nature of the used catalysts.

Publisher URL: http://dx.doi.org/10.1021/acscatal.7b01548

DOI: 10.1021/acscatal.7b01548