Impact of palladium/palladium hydride conversion on electrochemical CO 2 reduction via in-situ transmission electron microscopy and diffraction

• Published in: Nature communications Vol. 15; no. 1; p. 938
• Main Authors: Abdellah, Ahmed M, Ismail, Fatma, Siig, Oliver W, Yang, Jie, Andrei, Carmen M, DiCecco, Liza-Anastasia, Rakhsha, Amirhossein, Salem, Kholoud E, Grandfield, Kathryn, Bassim, Nabil, Black, Robert, Kastlunger, Georg, Soleymani, Leyla, Higgins, Drew
• Format: Journal Article
• Language: English
• Published: England 31.01.2024
• ISSN: 2041-1723

Electrochemical conversion of CO offers a sustainable route for producing fuels and chemicals. Pd-based catalysts are effective for converting CO into formate at low overpotentials and CO/H at high overpotentials, while undergoing poorly understood morphology and phase structure transformations under reaction conditions that impact performance. Herein, in-situ liquid-phase transmission electron microscopy and select area diffraction measurements are applied to track the morphology and Pd/PdH phase interconversion under reaction conditions as a function of electrode potential. These studies identify the degradation mechanisms, including poisoning and physical structure changes, occurring in PdH /Pd electrodes. Constant potential density functional theory calculations are used to probe the reaction mechanisms occurring on the PdH structures observed under reaction conditions. Microkinetic modeling reveals that the intercalation of *H into Pd is essential for formate production. However, the change in electrochemical CO conversion selectivity away from formate and towards CO/H at increasing overpotentials is due to electrode potential dependent changes in the reaction energetics and not a consequence of morphology or phase structure changes.