Role of water structure in high-performance CO2 electrolysis analysed via operando Raman spectroscopy

Role of water structure in high-performance CO2 electrolysis analysed via operando Raman spectroscopyAnku Guha a, F. Pelayo García de Arquer aa ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), 08860, SpainMaterials for Sustainable Development Conference (MATSUS)Proceedings of MATSUS Spring 2024 Conference (MATSUS24)#InOpCat - In situ and operando characterization of electrocatalytic interfacesBarcelona, Spain, 2024 March 4th - 8thOrganizers: Esther Alarcon-Llado, Jesus Barrio Hermida and Paula Sebastian PascualOral, Anku Guha, presentation 230DOI: https://doi.org/10.29363/nanoge.matsus.2024.230Publication date: 18th December 2023Tuning the electrode-electrolyte interfaces via cations, pH, and concentrations is a widely accepted method for tuning the product selectivity of electrochemical carbon dioxide reduction (CO2R) reaction in aqueous media. However, the role of the interfacial water remains an unsolved puzzle to date. Being a polar molecule, the water interacts either via the hydrogen end for cathodic reactions or via the oxygen end for anodic reactions by H-bonding or other chemical interactions to the electrode surface. In the electrode-electrolyte interface, water remains in mainly three forms: four H- H-bonded water (4-HB‧ H2O), three H-bonded water (3-HB‧ H2O), and free water (0-HB‧ H2O). Depending on the no of H-bonded water, the activation energy trend is 4-HB‧ H2O > 3-HB‧ H2O > 0-HB‧ H2O.[1,2] Presence of more rigid water (4-HB‧ H2O) in the electrode-electrolyte interface decreases the competing hydrogen evolution reaction (HER) [3] at the same time decreases the accessibility of CO2 to the catalytic surfaces impeding CO2R. [4] To explain this anomaly, we have employed in situ surface-enhanced Raman spectroscopy (SERS) to correlate the interfacial water structure with CO2RR product selectivity under higher current density using Cu as model catalyst varying the pH, concentration, cations, and anions of the electrolyte. The role of the interfacial pH, intermediate species specially adsorbed CO2, competition between carbonate/bicarbonate formation, and adsorbed hydroxide (*OH) are also explored. References:[1] Wang, Y.-H.; Zheng, S.; Yang, W.-M.; Zhou, R.-Y.; He, Q.-F.; Radjenovic, P.; Dong, J.-C.; Li, S.; Zheng, J.; Yang, Z.-L.; Attard, G.; Pan, F.; Tian, Z.-Q.; Li, J.-F. In Situ Raman Spectroscopy Reveals the Structure and Dissociation of Interfacial Water. Nature 2021, 600 (7887), 81–85.[2] Shen, L.; Lu, B.; Li, Y.; Liu, J.; Huang-fu, Z.; Peng, H.; Ye, J.; Qu, X.; Zhang, J.; Li, G.; Cai, W.; Jiang, Y.; Sun, S. Interfacial Structure of Water as a New Descriptor of the Hydrogen Evolution Reaction. Angewandte Chemie International Edition 2020, 59 (50), 22397–22402.[3] Guha, A.; Sahoo, M.; Alam, K.; Rao, D. K.; Sen, P.; Narayanan, T. N. Role of Water Structure in Alkaline Water Electrolysis. iScience 2022, 25 (8).[4] Wang, T.; Zhang, Z.-M.; Cai, Y.-C.; Li, X.-Y.; Ye, J.; Zhou, Y.; Tian, N. Probing the Mechanism of Cation Enhanced CO2 Reduction in Acidic Media: Water Structure Determining the Hydrogenation Kinetics. https://doi.org/10.21203/rs.3.rs-3181423/v1© FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. 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