10 research outputs found
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Continuum Model to Define the Chemistry and Mass Transfer in a Bicarbonate Electrolyzer
Bicarbonate electrolyzers are devices designed to convert CO2 captured from point sources or the atmosphere into chemicals and fuels without needing to first isolate pure CO2 gas. We report here an experimentally validated model that quantifies the reaction chemistry and mass transfer processes within the catalyst layer and cation exchange membrane layer of a bicarbonate electrolyzer. Our results demonstrate that two distinct chemical microenvironments are key to forming CO at high rates: an acidic membrane layer that promotes in situ CO2 formation and a basic catalyst layer that suppresses the hydrogen evolution reaction. We show that the rate of CO product formation can be increased by modulating the catalyst and membrane layer properties to increase the rate of in situ CO2 generation and transport to the cathode. These insights serve to inform the design of bicarbonate and BPM-based CO2 electrolyzers while demonstrating the value of modeling for resolving rate-determining processes in electrochemical systems
Novel triphenylamine-modified ruthenium(II) terpyridine complexes for nickel oxide-based cathodic dye-sensitized solar cells
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Electrolytic Methane Production from Reactive Carbon Solutions
We report an electrochemical reactor that converts 3.0 M KHCO3 into methane at the cathode, and oxidizes water at the anode. The molar ratio of methane product to unreacted CO2 gas (defined herein as "methane yield") was measured to be 34% at a partial current density of 120 mA cm-2. The highest previously reported CO2-to-methane yield is 3%. Our reactor achieved this improvement in methane yield because it is fed with 3.0 M KHCO3, a type of reactive carbon solution, rather than gaseous CO2. The reactor uses H+ delivered by a bipolar membrane to form CO2 at the cathode. This CO2 is subsequently reduced into methane. A cationic surfactant added to the catholyte suppressed hydrogen evolution and increased methane formation. A 1D continuum model confirmed that H+ from the membrane promotes the formation of methane over multicarbon products at the cathode. These findings present design principles for electrochemical methane synthesis