Carbon dioxide reduction and related reactions on copper and carbon electrocatalysts
File(s)
Author(s)
Oates, Rose
Type
Thesis
Abstract
Electrochemical carbon dioxide reduction is a promising, carbon-neutral technology capable of synthesising desirable commodity chemicals. The intermittency of renewable energy production, including wind and solar, can provide surplus electricity in times of low demand. This can be used to convert carbon dioxide to useful products such as ethanol and ethylene. However, the reaction suffers from the competing hydrogen evolution reaction and poor diffusion of CO2 through the electrolyte leading to lower selectivity and larger overpotentials. Currently, copper is the only single metal capable of producing desirable multi-carbon products. Further investigation is required into optimising copper catalysts to improve selectivity and activity towards one valuable product. In this thesis, a series of studies are carried out focussing on CO2 reduction and related reactions to try and advance this field.
Initially, hydrogen evolution activity of seven carbon black materials found in commercial electrochemical systems was investigated. Statistical analysis compared the electrochemical and physical data to establish the total metal content is the main contributing feature to increased activity.
Next, ultra-small ligated copper nanoparticles were studied for carbon dioxide reduction. It was established, using a flow cell, that the ligated copper materials have varying selectivity suggesting the ligands had influence on the performance. A unique electrochemistry mass spectrometer was used to optimise and elucidate the ligand’s influence on the copper nanomaterials for carbon monoxide reduction. The ligands with intermediate lengths were most active towards ethylene production. Potential control measurements established that the copper was not fully corroding in alkaline conditions and X-ray Photoelectron Spectroscopy and Low Energy Ion Spectroscopy supported this.
Finally, a novel high current density electrode design was optimised for CO2 reduction to carbon monoxide using gold nanoparticle catalysts. This study showed this new electrode is capable of mechanistic studies at higher current densities which is more relevant to real devices.
Initially, hydrogen evolution activity of seven carbon black materials found in commercial electrochemical systems was investigated. Statistical analysis compared the electrochemical and physical data to establish the total metal content is the main contributing feature to increased activity.
Next, ultra-small ligated copper nanoparticles were studied for carbon dioxide reduction. It was established, using a flow cell, that the ligated copper materials have varying selectivity suggesting the ligands had influence on the performance. A unique electrochemistry mass spectrometer was used to optimise and elucidate the ligand’s influence on the copper nanomaterials for carbon monoxide reduction. The ligands with intermediate lengths were most active towards ethylene production. Potential control measurements established that the copper was not fully corroding in alkaline conditions and X-ray Photoelectron Spectroscopy and Low Energy Ion Spectroscopy supported this.
Finally, a novel high current density electrode design was optimised for CO2 reduction to carbon monoxide using gold nanoparticle catalysts. This study showed this new electrode is capable of mechanistic studies at higher current densities which is more relevant to real devices.
Version
Open Access
Date Issued
2023-03
Date Awarded
2024-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Stephens, Ifan
Kucernak, Anthony
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/ R513052/1
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)