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Potential Step Methods for Fundamental Insights and Performance Enhancements in Electrochemical Carbon Dioxide Reduction

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2024-06-13
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Abstract

In the face of growing concerns about anthropogenic CO2 emissions and related climate change, scientists and engineers are looking to electrochemistry as an approach to address the rising atmospheric CO2 levels whereby renewably-sourced electricity is used to convert CO2 into other useful products. Crucial to bringing this vision to fruition is the development of catalysts and electrochemical systems that can stably reduce CO2 to value-added molecules at industrially relevant conditions with reasonable durability, lifetime, and product selectivity. There are many ways to modify the reaction conditions to change the outcome (e.g., changing the electrolyte or electrode material, decreasing the temperature, increasing the pressure, changing the potential, etc.). Pulsing electrochemical variables (e.g., voltage/current modulation) represents a simple experimental ‘knob’ to influence product selectivity and electrode longevity in electrochemical CO2 reduction (ECR). By tuning the interfacial factors (e.g., hydrodynamics, ad/desorption, surface reconstruction, catalyst oxidation, etc.) and their variations with pulse profile (e.g., duration and potential), the application of pulsed potential can tip the balance between transient physicochemical processes at the electrode/electrolyte interfaces, the result of which can impact the ECR reaction outcome. In the following chapters, we discuss in detail our findings concerning the use of potential modulation to control and study the ECR reaction. First, we present a review of pulsed potential ECR as a way to orient our work in the existing literature space. Then the effect of electrolyte concentration and composition on reaction selectivity under pulsed potential conditions along with the effect of pulse shape will be presented. We also present classical potential step chronoamperometric measurements to identify likely reaction pathways. We then use our insights on electrolyte, pulse shape, and reaction mechanism to study how the pulse mechanism on short time scales operates to identify the effects of pulsing on reaction activity towards high value products.

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2023-05

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chronoamperometry; competitive adsorption; electrical double layer; electrochemical CO2 reduction; pulsed potential; selectivity

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Hanrath, Tobias

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Suntivich, Jin
Archer, Lynden

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Chemical Engineering

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Ph. D., Chemical Engineering

Degree Level

Doctor of Philosophy

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Government Document

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Attribution 4.0 International

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dissertation or thesis

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