Evaluation of Carbon Anodes during Saltwater Electrolysis
Notice bibliographique
Résumé
Hydrogen is a promising alternative energy carrier to mitigate emissions arising from fossil fuel use. However, the most common methods of commercial hydrogen production, e.g., steam-methane reforming, are known to contribute significantly to greenhouse gas emissions. Therefore, there is significant interest in green hydrogen production through water electrolysis. At the same time, freshwater sources are limited and thus efforts are increasingly turning to saltwater electrolysis using renewable energy 1 . Key challenges encountered at the anode during saltwater electrolysis include the sluggish kinetics of the oxygen evolution reaction (OER) combined with low Faradaic efficiency due to competition from the chlorine evolution reaction (CER) 1 , as well as poor durability. The CER becomes a particular problem as electrolysis progresses because the local pH becomes more acidic as a result of the OER, causing the thermodynamic potentials of the OER and CER to become more similar 1,2 . However, Cl 2 is toxic and OCl - is corrosive to industrial equipment and thus we need to minimize chloride oxidation during saltwater electrolysis 1,2 . Current anode catalyst materials, such as metals and metal oxides, are known to be highly unstable at high potentials in chloride-containing solutions, while also being costly and lacking the desired selectivity towards the OER 3 . In addition, OCl - is known to make metallic anodes and other electrolyzer components susceptible to significant corrosion 3 . Thus, alternative anode materials that are low cost, catalytically active, and stable are needed. Carbon-based electrocatalysts are low in cost, readily available, relatively stable in neutral conditions, and can be easily functionalized to further enhance their activity and selectivity in various electrochemical systems 4 . However, few studies have investigated these systems, with little known yet about electrode stability or the impact of surface functionalization or heteroatom doping on carbon activity and selectivity in aqueous media and especially in saltwater. In the present work, we have evaluated the selectivity, activity and durability of a range of carbon materials, including graphite, graphene, carbon black, and colloid imprinted carbon powders, as anodes in salt solutions using cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. Multiple conditions have been varied to obtain a full picture of the electrochemistry underway, including doping the best performing carbons with nitrogen, altering the solution flow rate and varying the cell design. We are also tracking the solution concentration of all oxidized chloride species that are formed, while also monitoring the solution pH, and the composition of the gas evolved at the anode to determine the amount of oxygen vs chlorine gas produced. A detailed discussion and analysis of the electrochemistry, combined with chemical and physical characterization of the electrode materials and computational efforts, will be presented. Acknowledgements: This research is supported by the Natural Science and Engineering Research Council of Canada, the Canada First Research Excellence Fund, Alberta Innovates, Evolve Hydrogen Inc., Qualicase Ltd., and Fidelity Manufacturing Group. References: (1) Dresp, S.; Dionigi, F.; Klingenhof, M.; Strasser, P. ACS Energy Letters . 2019, pp 933–942. https://doi.org/10.1021/acsenergylett.9b00220. (2) Tang, X.; Arif, I.; Diao, P. Journal of Electroanalytical Chemistry 2023 , 942 , 1–7. https://doi.org/10.1016/j.jelechem.2023.117569. (3) Tiwari, J. N.; Sultan, S.; Myung, C. W.; Yoon, T.; Li, N.; Ha, M.; Harzandi, A. M.; Park, H. J.; Kim, D. Y.; Chandrasekaran, S. S.; Lee, W. G.; Vij, V.; Kang, H.; Shin, T. J.; Shin, H. S.; Lee, G.; Lee, Z.; Kim, K. S. Nat Energy 2018 , 3 (9), 773–782. https://doi.org/10.1038/s41560-018-0209-x. (4) Younis, M. A.; Lyu, S.; Zhao, Q.; Lei, C.; Zhang, P.; Yang, B.; Li, Z.; Lei, L.; Hou, Y.; Feng, X. BMC Mater 2019 , 1 (1). https://doi.org/10.1186/s42833-019-0006-2.
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Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
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