Mechanistic aspects of electrocatalysis using metal oxide and sulphide electrode materials

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Electrochemistry is now widely used to activate catalysts to perform a range of catalytic reactions, such as CO2 reduction. The two systems of interest in this project are copper and iron based oxide or sulphide catalysts. It has been shown that CO2, (although benign, but has significant effect on the climate change), can be activated to a more reactive state under electrochemical conditions using these catalysts. Whilst catalytic studies and many ex situ characterization methods have been employed to understand the nature of the catalyst, very little has been done to develop in situ methods to determine the nature of the catalyst under operating conditions, which is essential to determine the role of transient and steady state species responsible for catalytic reaction. This project will focus on developing in situ spectroscopic methods, in particular X-ray absorption spectroscopy (as it is element specific and does not require long-range order for structural study) and complementary infrared spectroscopy (which focuses on the vibrational modes of the reactants) to determine precisely the electronic and geometric state of the catalysts and reactants during reaction. The two systems we will use as exemplar for the study will be copper oxides and iron sulphides. Whilst there are research papers in this area, to our knowledge very little is known about the nature of metal centre (oxidation state, coordination) under reaction conditions. For example, both copper metal particles along with their oxides and Cu2O are the active phases present in the catalyst. Similarly, disordered (amorphous) FeS is proposed as active phase, but very little structural evidence is available in the literature.Therefore, the aim of this project is to develop in situ methods to understand the reacting and reactive state of copper and iron during electrochemical CO2 reduction, using X-ray absorption spectroscopy. Along with this in situ infra-red techniques will be used to monitor adsorbed reactants, intermediate and products at the electrode. The outcome will be a thorough understanding of the mechanism of catalysis of this important reaction.