An exploration of molecular electro- and photocatalysts towards carbon dioxide reduction and hydrogen evolution
Frayne, Liam
(2017)
An exploration of molecular electro- and photocatalysts towards carbon dioxide reduction and hydrogen evolution.
PhD thesis, Dublin City University.
The research presented in this thesis focusses on photo- and electrocatalysts for CO2 reduction and an electrocatalyst towards proton reduction to hydrogen. Introduced in Chapter one is a brief overview of the issues surrounding rising CO2 levels and energy consumption, in addition to a literature survey covering intramolecular photocatalytic systems towards CO2 reduction, the recent advancements in the field of molecular electrocatalysts for CO2 reduction and Co-centred molecular electrocatalysts active towards proton reduction in organic electrolyte. Chapter two reports the assessment of a dinuclear ruthenium-quaterpyridine-rhenium complex towards photocatalytic CO2 reduction. Communication between the metal centres was assessed through electrochemistry, UV- and IR-spectroelectrochemistry. Within Chapter three, four cobalt salens are screened as potential homogeneous CO2 electrocatalysts. Of these, the complex, bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamino cobalt(II) (CobdtChexSal) demonstrated the highest activity in DMF/5% water, with CO observed. With a higher level of charge consumption, H2 evolution became prevalent.Chapter four explores the potential of bis(salicylideniminato-3-propyl)methylamino cobalt(II) (CopdSal), for the electrocatalytic generation of hydrogen. Homogeneous solutions or electro-deposited catalytically active electrodes led to the generation of hydrogen. Techniques including electrochemistry, FESEM with EDX and UV-vis monitored electrolyses were utilised in gaining information as to the identity of the active catalyst. Chapter five contains details regarding materials used and methods undertaken within Chapters two to four. Chapter six concludes and discusses future work regarding chapters two, three and four.