Master of Science in Chemical Engineering (MSChE)
An efficient method to convert CO2 to fuels using renewable energy could displace crude oil without increasing CO2 emission and provide high-density energy storage reservoirs similar to liquid fuels or batteries. Although photoelectrochemical conversion of CO2 is possible, solar-to-fuel efficiencies are lower than the combination of conventional photovoltaics (up to 40% efficiency) and electrochemical cells (up to 80% Faradaic efficiency). In the electrochemical case, electrical energy from renewable sources may be converted to hydrocarbons or alcohols using electrocatalysts. The direct reduction of CO2 to CH3OH is known to occur at several types of electrocatalysts including oxidized Cu electrodes. In this thesis, we first examine the yield behavior of an electrodeposited cuprous oxide thin film and explore relationships between surface chemistry and reaction behavior relative to air-oxidized and anodized Cu electrodes. CH3OH yields and Faradaic efficiencies observed at cuprous oxide electrodes are remarkably higher than air-oxidized or anodized Cu electrodes suggesting Cu(I) species may play a critical role in selectivity to CH3OH. Experimental results also show CH3OH yields are dynamic and the copper oxides are reduced to metallic Cu in a simultaneous process. In order to improve CH3OH activity and electrode surface’s stability, single crystal ZnO (10-10) is considered as a support since ZnO support are well known for methanol synthesis in an industrial hydrogenation reaction scale. Although experimental conditions pose challenging barriers to repeatability, Infrared Spectroscopy and yields suggest the oxide may provide stable surfaces with selectivity to CH3OH. Yield behavior is discussed in comparison with photoelectrochemical and hydrogenation reactions where the improved stability of Cu(I) species may allow relatively constant CH3OH generation.
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Le, Minh Tuyen Hoang, "Electrochemical reduction of CO2 to methanol" (2011). LSU Master's Theses. 605.
Flake, John C.