BUSCADOR RECOLECTA

Scaling up CO2 electroreduction to formate faces several challenges, including using chemicals as electrolytes and high energy demands. To address these issues, this study uses an industrial stream—specifically a caustic soda stream from the textile industry—as anolytes for the oxygen evolution reaction (OER). Using this approach, formate concentrations of 226 g L⁻¹ and Faradaic efficiencies (FE) of 53 % are achieved at 200 mA cm⁻², demonstrating the competitiveness of industrial streams compared to synthetic anolyte solutions. Various anode materials are tested to optimize OER kinetics under industrial conditions and reduce energy consumption. Ni foam exhibited promising results, achieving FEs of 78 % and 58 % at 90 and 200 mA cm⁻², with energy consumption between 236 and 385 kWh kmol⁻¹ , making it one of the most efficient options among commercially available materials. In addition, alternative materials, such as NiFeOx and NiZnFeOx particulate anodes, are synthesized to provide viable substitutes for commercial anodes that rely on scarce elements. These alternatives demonstrated similar formate concentrations, with FEs up to 74 % and reduced energy requirements compared to commercial NiO. The synthesized NiFe foam anode excelled in performance, with energy consumption below 210 and 380 kWh kmol⁻¹ and an impressive formate production of 255 g L−1 of formate achieving a 60 % FE at 200 mA cm−2. Overall, this research demonstrates the feasibility of CO₂ electroreduction to formate using textile effluents under relevant conditions, representing a significant step toward making this process a competitive option for decarbonizing hard-to-abate industries., The authors gratefully acknowledge Grant TED2021-129810B-C21 and PLEC2022-009398 funded by MICIU/AEI/10.13039/501100011033/ and by the “European Union NextGenerationEU/PRTR”, and Grants PID2022-138491OB-C31, and PID2022-138491OB-C32, funded by MICIU/AEI/10.13039/501100011033 and by “ERDF/EU”. The present work is related to CAPTUS Project. This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101118265. J. A. Abarca gratefully acknowledges the predoctoral research grant (FPI) PRE2021-097200.

The electrocatalytic reduction of CO2 to formate or formic acid represents a promising approach to mitigating CO2 emissions. Despite progress with Bi and Sn-based cathodes, there remains a demand for new electrocatalytic materials with enhanced activity for industrial-scale implementation. In a recent contribution, carbon-supported Bi-Sn-Sb nanoparticles with different atomic ratios were prepared and evaluated for the electrocatalytic reduction of CO2 to formate, assessing their performance in terms of activity, selectivity, and stability under working conditions in an H-type cell. Under this electrochemical reactor configuration, the results clearly indicated that the incorporation of small amounts of Sb and Sn into Bi significantly enhanced stability without substantially affecting activity and selectivity, achieving promising results with Bi80Sn10Sb10 electrocatalysts. Here, we report the use of Bi-Sn-Sb-based Gas Diffusion Electrodes (GDEs) in a flow electrochemical reactor for the electrocatalytic reduction of CO2 to formate. The study also aims to rigorously compare the performance of Bi-Sn-Sb GDEs with that of analogous GDEs based solely on Bi or Sn. When compared to relevant references, the Bi-Sn-Sb catalyst demonstrates performance metrics that reflect comparable system efficiency to the Bi and Sn cathodes previously used by our research group, operating at current densities up to 200 mA·cm−2 and achieving formate concentrations of approximately 15 g·L−1. Furthermore, these materials exhibited technical feasibility, remaining stable throughout the 5-hour experiment with less than a 10 % decrease in concentration. This stability marks a vital first step toward the future implementation of this type of cathode in the electrochemical reduction of CO₂ to formate., The authors fully acknowledge the financial support received from the Spanish Research Agency (AEI) through projects PID2022–138491OB-C31, PID2022–138491OB-C32 (MICIU/AEI/10.13039/501100011033 and by ERDF/EU), TED2021–129810B-C21 (MCIN/AEI /10.13039/501100011033), PLEC2022–009398 (MCIN/AEI/10.13039/501100011033 and European Union Next Generation EU/PRTR) and the “Complementary Plan in the area of Energy and Renewable Hydrogen” (funded by Autonomous Community of Cantabria, Spain, and the European Union Next GenerationEU/PRTR). The present work is related to CAPTUS Project. This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement Nº 101118265.

The development of efficient photoanodes that reduce external energy requirements for the electrochemical conversion of CO2 to formate is essential for the future implementation of this technology. In this work, we explore different photoanode structures based on electrodeposited BiVO4 onto transparent FTO substrates to achieve a more efficient PEC reduction of CO2. Among the tested structures, the photoanode incorporating a Bi2O3 underlayer, which enhances the BiVO4-FTO interface by reducing electron-hole recombination, exhibits the best PEC performance. Integrating this photoanode into a CO2 photoelectrolyzer with back visible light illumination achieves an impressive current density of −29 mA cm−2 at constant −1.8 V (vs. Ag/AgCl). Using a Bi/C GDE as the cathode, the system produces up to 56.2 g L−1 of formate with a Faradaic efficiency of 96 %. In terms of energy performance, illuminating the photoanode reduces energy consumption by nearly 40 %, bringing it down to 317 kWh kmol−1, with an energy efficiency of 38 %. The external bias can be further decreased by increasing the irradiation intensity to 2.5 suns using concentrated solar light, resulting in an additional 10 % reduction in energy consumption (290 kWh kmol−1), while maintaining high conversion efficiencies for CO2 to formate (over 95 % Faradaic efficiency). Besides, energy efficiency improves by 12 %, as the cathodic potential is reduced to −1.65 V (vs. Ag/AgCl). These results represent significant progress in reducing the external bias required for CO2 to formate conversion in PEC systems, marking a step toward the industrial application of CO2 conversion technology., The authors gratefully acknowledge Grant TED2021-129810B-C21 and PLEC2022-009398 funded by MICIU/AEI/10.13039/501100011033/ and by the “European Union NextGenerationEU/PRTR”, and Grants PID2022-138491OB-C31, PID2022-138491OB-C32 and PID2022-138491OB-C33 funded by MICIU/AEI/10.13039/501100011033 and by “ERDF/EU”. This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101118265. Marti Molera acknowledges AGAUR-Generalitat de Catalunya for 2024 FI-1 00421 predoctoral grant. The authors thank Dr. Julià Lopez Vidrier for the access to the UV–vis equipment. Jose Antonio Abarca gratefully acknowledges the predoctoral research grant (FPI) PRE2021-097200. Ivan Merino-Garcia also acknowledges Grant RYC2023-043378-I funded by MICIU/AEI/10.13039/ 501100011033 and by ESF + .

The application of external magnetic fields in electrochemical processes has emerged as a promising strategy to enhance efficiency. Nevertheless, the use of magnetic fields in electrochemical CO2 reduction (ERCO2) has been scarcely explored. This study evaluates the impact of magnetic fields on ERCO2 to formate in a filter-press reactor, combining experimental analysis with magnetic field modeling to understand the performance enhancements achieved by placing magnets outside the electrochemical cell. Magnetic field modeling reveals that the positioning of magnets relative to the cathode surface significantly affects the field strength. For instance, placing a magnet near the anode generates a field strength of 20 mT on the GDE, while positioning two magnets at opposite ends of the cell increases the field to 400 mT. Experimentally, placing magnets near the cathode or at both ends of the cell boosts formate concentration by more than 20 %, achieving values of 4.4 g L−1 and 4.95 g L−1, respectively, with FEs approaching 100 %. These improvements are attributed to the magnetohydrodynamic (MHD) effect, which enhances mass transfer by inducing turbulence in the cathodic electrolyte. This effect is particularly important at low catholyte flow rates, leading to a more than 50 % increase in formate concentration, reaching up to 27.25 g L−1 at a flow rate of 0.07 mL min−1 cm−2. However, the application of magnetic fields also increases energy consumption due to the higher cell voltage requirements, as indicated by Tafel analysis. Despite this limitation, this study demonstrates the potential application of magnetic fields to enhance ERCO2 processes, paving the way for future research to further explore and optimize this promising strategy., The authors fully acknowledge the financial support received from the Spanish State Research Agency (AEI) through the projects PID2022-138491OB-C31 and PID2022-138491OB-C32 (MICIU/AEI /10.13039/501100011033 and FEDER, UE), TED2021-129810B-C21, and PLEC2022-009398 (MCIN/AEI/10.13039/501100011033 and Union Europea Next Generation EU/PRTR). The present work is related to CAPTUS Project. This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101118265. This study was financially supported by Texas Tech University through HEF New Faculty Startup, NRUF Start Up, and Core Research Support Fund. Jose Antonio Abarca gratefully acknowledges the predoctoral research grant (FPI) PRE2021-097200. Cristina González-Fernández thanks the Spanish Ministry of Universities for the Margarita Salas postdoctoral fellowship (grants for the requalification of the Spanish university system for 2021-2023, University of Cantabria), funded by the European Union-NextGenerationEU. Joseph A Gauthier gratefully acknowledges support from The Welch Foundation under Grant Number D-2188-20240404. Jenifer Gomez-Pastora acknowledges support from The Welch Foundation (Grant # D-2236-20250403).