Ionomer-Modulated Electrochemical Interface Leading to Improved Selectivity and Stability of Cu<sub>2</sub>O-Derived Catalysts for CO<sub>2</sub> Electroreduction
Matt L. J. Peerlings, Maaike E. T. Vink‐van Ittersum, Jan Willem de Rijk, Petra E. de Jongh, Peter Ngene
Abstract
High Resolution Image Download MS PowerPoint Slide Copper is an attractive catalyst for the electrochemical reduction of CO 2 to high value C 2+ products such as ethylene and ethanol. However, the activity, selectivity and stability of Cu-based catalysts must be improved for industrial applications. In this work, we investigate the effects of ionomers on the microenvironment and consequently the catalytic performance of Cu 2 O particles with a well-defined cubic shape. Cu 2 O particles without an ionomer coating were compared to those with a Nafion-based cation-exchange layer (CEL) and a Sustainion-based anion-exchange layer (AEL), as well as electrodes with two successive layers of Nafion and Sustainion in either order. Using these model electrodes, we found that the selectivity to C 2+ products is significantly improved with a Nafion coating, regardless of whether it is in direct contact with the copper surface or present as an overlayer on top of chloride-exchanged Sustainion. The selectivity improvement by Nafion is ascribed to the exclusion of proton-donating bicarbonate ions, which limits the competing hydrogen evolution reaction. Interestingly, introducing a second layer of Sustainion causes a selectivity shift from ethylene to ethanol. In addition, improved catalyst stability is observed for the Nafion-containing electrodes due to a mitigation of potassium bicarbonate precipitation and copper agglomeration. These results demonstrate that regulating the catalyst microenvironment via ionomer coatings is a promising approach to designing electrodes with superior and tunable catalytic performance.