Electron Paramagnetic Resonance Studies of Metal Organic Frameworks in Catalysis

Abstract

The conversion of CO2 into value-added chemicals and fuels has attracted wideranging attention owing to ever-increasing environmental concerns. In this project, electrocatalytic reduction of CO2 (CO2RR) was chosen for CO2 conversion because the process can be conducted at room temperature and simply controlled by adjusting the potentials, and the electricity can come from green energy. Porous metal-organic frameworks (MOFs) constructed from metals and organic linkers have emerged as efficient catalysts for the CO2RR. The advantages of MOFs and their derivatives as catalysts for CO2RR are: (i) the atomically dispersed metal sites can act as active sites. (ii) the porous structure of MOFs makes the reactants easily get to the accessible active sites. (iii) guest species can be introduced into the pore to improve the activity and selectivity of MOFs. In this project, bismuth-based and copper-based MOFs are synthesized for CO2RR. Electron paramagnetic resonance (EPR) and other techniques are used to monitor the radical produced and the change of catalysts during the CO2RR. Besides, EPR was also used to characterize the catalysts and radical intermediates in the photocatalytic and thermocatalytic reactions. Chapter 1 outlines the importance and advantages of electrocatalytic CO2 reduction by using porous MOFs and derivatives as catalysts. The application of EPR in characterizing MOFs and intermediate radicals in catalysis is introduced. Chapter 2 demonstrates the impact of porosity of bismuth MOFs on their structural evolution during the CO2RR. Chapter 3 provides one way to control the structural evolution of porous copper-based metal-organic materials for efficient CO2RR to multi-carbon products. Chapter 4 explores the catalytic ability of one novel electrode grown on Cu-foam for CO2RR. Chapter 5 studies the catalysts and radical intermediate by electron paramagnetic resonance in the photocatalytic and thermocatalytic reactions. Chapter 6 lists the conclusions of the specific work and additional work that has been done but is not included in chapter 2-5.

Date of Award	7 Nov 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Eric Mcinnes (Supervisor), Floriana Tuna (Supervisor) & Sihai Yang (Supervisor)