Catalysts

13 pages, 4026 KiB

Open AccessFeature PaperArticle

Elucidating the Influence of Electric Fields toward CO₂ Activation on YSZ (111)

by Nisa Ulumuddin, Fanglin Che, Jung-Il Yang, Su Ha and Jean-Sabin McEwen

Catalysts 2021, 11(2), 271; https://doi.org/10.3390/catal11020271 - 18 Feb 2021

Cited by 8 | Viewed by 4110

Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO₂ through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO₂ molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO₂ on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO₂ adsorbs on the surface. CO₂ is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO₃⁻ complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the O_latticep-states. While CO₂ remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO₂ adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO₂ reduction on heterogeneous catalysts. Full article

(This article belongs to the Special Issue Electrocatalytic Processing of Biomass for Energy Conversion and Storage)

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8 pages, 2562 KiB

Open AccessPerspective

Electrocatalysts for Using Renewably-Sourced, Organic Electrolytes for Redox Flow Batteries

by Robert S. Weber

Catalysts 2021, 11(3), 315; https://doi.org/10.3390/catal11030315 - 28 Feb 2021

Cited by 1 | Viewed by 2255

Abstract

Biomass could be a source of the redox shuttles that have shown promise for operation as high potential, organic electrolytes for redox flow batteries. There is a sufficient quantity of biomass to satisfy the growing demand to buffer the episodic nature of renewably produced electricity. However, despite a century of effort, it is still not evident how to use existing information from organic electrochemistry to design the electrocatalysts or supporting electrolytes that will confer the required activity, selectivity and longevity. In this research, the use of a fiducial reaction to normalize reaction rates is shown to fail. Full article

(This article belongs to the Special Issue Electrocatalytic Processing of Biomass for Energy Conversion and Storage)

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