Anodic Halogenation of Copper Surface for Selective Electrocatalytic CO2 reduction toward C2 and C3 Products

Kim, Taehee

Full Metadata

Overview

Year:: 2020
Contributor:: Kim, Taehee (creator); Palmore, Tayhas (Advisor); Hurt, Robert (Reader); Sun, Shouheng (Reader); Brown University. School of Engineering (sponsor)
Genre:: theses
Subject:: CO2 electrochemical reduction
Extent:: 13, 87 p.
DOI: https://doi.org/10.26300/dhr7-e725

Files

Description

Abstract:: Development of efficient catalysts for the selective electroreduction of carbon dioxide (CO2) to high-value products is essential to the deployment of carbon capture and utilization technologies. In this work, a scalable method for preparing Cu electrocatalysts that favor CO2 conversion to C2+ products is presented. This method involves anodic halogenation of Cu foils and their subsequent surface reconstruction via oxide-formation and electrochemical reduction. This method results in catalysts that convert CO2 to ethylene with faradaic efficiencies (FE) up to 50.0% and with FE for total C2+ products of 72% at -1.09 V vs. reversible hydrogen electrode (RHE). Grazing-incidence X-ray diffraction (GI-XRD) was utilized to confirm that anodic halogenation of electropolished Cu foils in aqueous solutions of KCl, KBr, or KI creates surfaces of CuCl, CuBr, or CuI, respectively. Results from scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) studies show that significant changes to the morphology of Cu occur during anodic halogenation and subsequent oxide-formation and reduction, resulting in catalysts with a high density of defect sites but relatively low roughness. These defect sites facilitate C-C coupling reactions of adsorbed carbon intermediates, leading to the formation of C2 products such as ethylene. Excessive anodic halogenation (i.e., longer reaction times) diminishes C-C coupling reactions by increasing the roughness of the Cu surface to the point of favoring the competing hydrogen evolution reaction (HER). This work has demonstrated that a high density of defect sites and a low roughness are the key design criteria for efficient electrocatalysts in CO2 reduction.
Notes:: Thesis (Ph. D.)--Brown University, 2020

Content

Access Conditions

Rights: In Copyright
Restrictions on Use: Collection is open for research.

Citation

Kim, Taehee, "Anodic Halogenation of Copper Surface for Selective Electrocatalytic CO2 reduction toward C2 and C3 Products" (2020). Engineering Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.26300/dhr7-e725

Relations

Collection:

Engineering Theses and Dissertations

Theses and Dissertations for the Engineering department.
...