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Author
Cerrada Solé, Constança
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As greenhouse gas emissions continue to rise, carbon capture and use technologies have been proposed as an attractive way to alleviate the build-up of CO2 in the atmosphere and also have a positive impact on climate change. Electrochemical CO2 reduction has been postulated as a favorable strategy for renewable energy storage and electrification of the chemical industry. However, for a positive impact, large-scale implementation of this technology is required. Most of the research has focused on the fundamental and mechanistic understanding of CO2RR and on the development of highly active and selective catalytic materials.
The focus of this work is to address a very important challenge to scale the technology and, therefore, the limitation of mass transfer, which is highly related to the architecture of the electrode, the operating conditions and the design of the reactor. Our strategy to overcome the aforementioned challenge has been based on the implementation of 3D electrode architectures to facilitate the transfer of mass and charge in the gas diffusion electrodes (GDE) both for half-reactions (OER and CO2RR) and for the evaluation of cells. complete electrochemicals that are CO2 electrolyzers in two operating modes: liquid and gas.
GDEs based on silver (as it is very selective towards CO) were selected for CO2RR, and based on nickel for OER. First a first screening was carried out in a reactor with a three electrode configuration. The electrodes that performed the best for the development of CO2 electrolysers were GDEs based on Ag with a PTFE layer, and those based on nickel with a network of microfibers (Ni felt). The liquid phase operation was carried out in a two-compartment electrolyzer separated by a bipolar membrane (where CO2 was introduced into the catholyte), and the gas phase operation in a two-compartment electrolyzer separated by an anion exchange membrane. . Performance indicators were current density and Faraday efficiency. The observations from this study suggest that the gas phase electrolyzer offers a possible avenue for future industrial purposes.
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