In-Situ Liquid Phase Transmission Electron Microscopy and Electron Diffraction Provides Mechanistic Insight into Electrochemical CO2 Reduction on Palladium/Palladium Hydride Catalysts



Electrochemical conversion of CO2 (CO2R) offers a sustainable route for producing fuels and chemicals. Pd-based catalysts are effective for selective conversion of CO2 into formate at low overpotentials and CO/H2 at high overpotentials. Furthermore, Pd catalysts undergo morphology and phase structure transformations under reaction conditions that are not well understood. Herein, in-situ liquid phase transmission electron microscopy (LP-TEM) and select area diffraction (SAD) measurements under CO2R conditions is applied to track the morphology and Pd/PdHx phase interconversion as a function of electrode potential, respectively. Correlating in-situ characterization with electrochemical CO2R activity/selectivity measurements, density functional theory and micro-kinetic analyses, the change in Pd/PdHx catalyst selectivity from formate at low overpotentials towards CO/H2 at higher overpotentials is found to result from electrode potential-dependent thermodynamic changes in the reaction energetics and not morphological or phase structure changes, providing insight that can guide advanced understanding and design of improved performance catalysts.


Thumbnail image of In situ TEM of Pd-PdHx - Manuscript - 23Jan23.pdf

Supplementary material

Thumbnail image of In situ TEM on Pd-PdHx - Supporting Information - Clean - 23Jan23.pdf
Supporting Information
Includes additional figures and details pertaining to the manuscript.
Thumbnail image of Video S1.mp4
Video S1
Video of particle growth under applied electrochemical bias
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Video S2
Diffraction pattern changes as a function of electrode potential, indicating lattice expansion due to Pd to PdHx phase transformation
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Video S3
Particle morphology changes and migration as a function of time under electrochemical CO2 reduction conditions