Electrochemical CO2 reduction on Cucurbit[n]uril modified Gold
type: CreativeWork
description: The electrochemical conversion of carbon dioxide with renewable electricity offers an attractive route towards sustainable fuel and chemical feedstock production. However, the reaction suffers from slow reaction kinetics, low solubility of CO2 and hydrogen formation as a competing side reaction. In general, rational control over reaction intermediates via (de-)stabilising interactions remains a major challenge in electrocatalysis more broadly. In this thesis, gold surfaces were functionalised with cucurbit[n]uril (CB[n]) macrocycles to form a hybrid organic-inorganic model system capable of influencing the local chemical environment of gold as a heterogeneous CO2 reduction electrocatalyst. This supramolecular system was carefully investigated with an interdisciplinary approach to uncover the complex dynamics at the interface. The binding of CO2 within the CB[6] cavity in aqueous electrolytes as well as CB[6] surface binding were studied with numerous experimental and theoretical techniques. Surface enhanced infrared spectroscopy in combination with electrochemistry illustrated the formation of a CB[6]•CO2 complex on the gold surface. The reaction rate and selectivity of CO2 reduction were evaluated with a purpose-built setup that automatically sampled multiple electrolysis cells with in-line gas chromatography. In pure CO2 atmosphere, the adsorption of CB[6] selectively decreased the partial CO formation rate at low overpotentials while the hydrogen formation rate was unchanged compared to unfunctionalised Au. Upon reducing the concentration of CO2, it was found that this trend reversed and CB-functionalisation selectively suppressed hydrogen formation compared to CO2 reduction. A more detailed rate analysis with varying CO2 and bicarbonate concentrations indicated a strong dependence on the ionic strength of the electrolyte and suggested decreased hydrogen formation from bicarbonate as the proton donor under low CO2 concentrations. Additional chemical tunability of…
abstract: The electrochemical conversion of carbon dioxide with renewable electricity offers an attractive route towards sustainable fuel and chemical feedstock production. However, the reaction suffers from slow reaction kinetics, low solubility of CO2 and hydrogen formation as a competing side reaction. In general, rational control over reaction intermediates via (de-)stabilising interactions remains a major challenge in electrocatalysis more broadly. In this thesis, gold surfaces were functionalised with cucurbit[n]uril (CB[n]) macrocycles to form a hybrid organic-inorganic model system capable of influencing the local chemical environment of gold as a heterogeneous CO2 reduction electrocatalyst. This supramolecular system was carefully investigated with an interdisciplinary approach to uncover the complex dynamics at the interface. The binding of CO2 within the CB[6] cavity in aqueous electrolytes as well as CB[6] surface binding were studied with numerous experimental and theoretical techniques. Surface enhanced infrared spectroscopy in combination with electrochemistry illustrated the formation of a CB[6]•CO2 complex on the gold surface. The reaction rate and selectivity of CO2 reduction were evaluated with a purpose-built setup that automatically sampled multiple electrolysis cells with in-line gas chromatography. In pure CO2 atmosphere, the adsorption of CB[6] selectively decreased the partial CO formation rate at low overpotentials while the hydrogen formation rate was unchanged compared to unfunctionalised Au. Upon reducing the concentration of CO2, it was found that this trend reversed and CB-functionalisation selectively suppressed hydrogen formation compared to CO2 reduction. A more detailed rate analysis with varying CO2 and bicarbonate concentrations indicated a strong dependence on the ionic strength of the electrolyte and suggested decreased hydrogen formation from bicarbonate as the proton donor under low CO2 concentrations. Additional chemical tunability of…
author: Wagner, Andreas
language: eng
keywords: electrocatalysis, surface chemistry, Cucurbituril, supramolecular chemistry, molecular surface functionalisation
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/d89ab152-dd5d-4bc6-ace6-73154a42de9b/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2020-04-01
date modified: 2026-07-22T22:24:11Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.54851