CO2 electroreduction to formate: Continuous single-pass operation in a filter-press reactor at high current densities using Bi gas diffusion electrodes. (December 2019)

• Record Type: Journal Article
• Authors: Díaz-Sainz, G.; Alvarez-Guerra, M.; Solla-Gullón, J.; García-Cruz, L.; Montiel, V.; Irabien, A.
• Is Part Of: Journal of CO₂ utilization. Volume 34(2019)
• Page Start: 12
• Page End: 19
• Publication Date: 2019-12
• Subjects: CO2electroreduction -- Bismuth nanoparticles -- Formate -- GDEs (gas diffusion electrodes) -- Continuous filter-press cell; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2019.05.035
• Languages: English
• ISSNs: 2212-9820

Abstract

Graphical abstract: Highlights: Carbon-supported Bi nanoparticles were used to fabricate Bi Gas Diffusion Electrodes (Bi-GDEs). Formate was obtained in a continuous mode with one pass in a filter-press reactor. Bi-GDEs were able to work at a current density up to 300 mA cm −2 . At 200 mA cm −2, 4 g L −1 of formate was obtained with a high Faradaic Efficiency (80%). Concentrations of formate of up to 18 g L −1 were obtained. Abstract: Electrocatalytic reduction of CO2 has been taken into consideration as a fascinating option to store energy from intermittent renewable sources in the form of chemical value-added products. Among the different value-added products, formic acid or formate is particularly attractive since it can be used as a fuel for low-temperature fuel-cells and as a renewable hydrogen carrier. Very recently, a rapidly increasing number of studies have revealed Bi as a promising electrocatalytic material for the CO2 electroreduction to formate, but the performance of Bi electrodes operating in a continuous mode and high current density (j) has been hardly investigated yet. Thus, this work aims at studying the CO2 electroreduction to formate working in a continuous mode in a filter-press-reactor at a j up to 300 mA·cm −2 using Bi electrodes. Bismuth Gas Diffusion Electrodes (Bi-GDEs) were fabricated from carbon-supported Bismuth-nanoparticles. The influence of j and the electrolyte flow/area ratio in the performance of the Bi-GDEs towards formate were evaluated. Working at j of 300 mA·cm −2, a concentration of 5.2 g formate·L −1 with a faradaic efficiency (FE) and rate of 70% and 11 mmol·m −2 ·s −1, respectively were achieved. Lowering the j to 90 mA·cm −2, formate concentrations of up to 7.5 g·L −1 could be obtained with an excellent FE of 90%. Interestingly, the highest concentration of formate obtained was 18 g·L −1, but at expenses of an important decrease in FE. Although the results of this study are interesting and promising, further research is required to increase formate concentration for a future implementation at industrial scale.