(450f) MOF-Enabled Microenvironment Control for Electrocatalytic Carbon Monoxide Reduction

Although electrochemical CO₂ reduction reaction (CO₂RR) has been considered a promising carbon-neutrality system, its low level of selectivity for the production of specific chemicals limits further developments, except for the conversion of CO₂ to CO (>99% selectivity). Recently, the electrochemical CO reduction reaction (CORR) has been receiving a great deal of attention owing to its better selectivity for conversion to specific chemicals than that of CO₂RR. Recent progress demonstrated that the Faradic efficiency of C2+ for CORR (~80%) was much higher than that for CO₂RR (~55%).¹

Although various methods have been developed to efficiently convert CO₂ into CO, the conversion of CO into desired C2+ products remains poorly comprehended. Notably, the hydrogen evolution reaction (HER) from water breakdown emerges as the predominant product across all potentials.² While several catalyst-based strategies have been pursued, little progress has been made in enhancing selectivity.³ The microenvironment at a solid electrode surface defines catalyst accessibility, selectivity, and activity. Therefore, understanding and engineering the catalyst/electrolyte interface provides a pathway to enhancing selectivity to hydrogenated products while suppressing undesired HER.

In this study, we investigate two approaches: (1) Transitioning from aqueous electrolytes to aprotic-water mixtures to modulate water activity and allow water solely as a proton source, and (2) Coating copper catalysts with metal-organic frameworks (MOFs) designed to concentrate CO and interfacial water for enhanced C-C coupling. Employing Molecular Dynamics and Density Functional Theory simulations, we delve into the structure and dynamics of the microenvironment surrounding copper electrodes coated with MOFs like ZIF-8 and Nu-901. Our primary focus is on gaining a molecular-level understanding of the electrolyte mixture's structure and dynamics at both bare and MOF-coated copper electrodes.

References

1. Jouny et al., Nat. Catal. 1, 2018, 748–755.
2. Wang et al., ACS Catal. 2018, 8, 7445
3. Bibi et al., Chem Catalysis, 2, 2022, 1961