Bimetallic Cu-based hollow fibre electrodes for CO2 electroreduction

The electrochemical reduction of CO2 represents an attractive alternative to both, i) satisfy the increasing energy demand, and ii) to help closing the carbon cycle. However, the energy required for CO2 activation and the subsequent required multiple number of proton-coupled electron transfer steps, makes this process very challenging. Besides, catalytic material limitations hamper the application of this technology in the short term. Consequently, in this work we synthesise, characterise and preliminarily evaluate bimetallic Cu-based hollow fibre electrodes with a compact three-dimensional geometry to overcome mass transfer limitations and to enhance the electrochemical conversion of CO2. The Cu hollow fibres are functionalised with Au in an attempt to tune the binding energy of the CO* intermediate, which appears to be key in the reduction of CO2. The Cu fibres are also functionalised with Ni, aiming to decrease the reaction overpotential, resulting in beneficial energy efficiency. The so prepared Cu-based porous hollow fibre electrodes are obtained by dry-wet spinning and electrodeposition procedures. The materials are then characterised by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analyses and cyclic voltammetry. Finally, preliminary results of CO2 electroreduction in a divided three-electrode cell are reported. The results show the potential of highly active, bimetallic hollow fibre-based electrocatalysts for enhanced conversion of CO2 into value-added products. Deposition of particles should be performed with care, not to affect pore characteristics and thus mass transfer properties.