Understanding the electrochemical reduction of carbon dioxide into formate using a tin-plated cathode
Sn has been a research interest for its ability in converting CO2 into its reduced form very efficiently and at a relatively low energy cost. However, a complete and exhaustive study for the usage of Sn in electrochemical reduction of CO2 still does not exist. Researchers often provide conflicting...
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| Format: | Thesis |
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| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77169/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77169/2/Full%20text.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77169/4/Tan%20Teik%20Aun.pdf |
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| Summary: | Sn has been a research interest for its ability in converting CO2 into its reduced form very efficiently and at a relatively low energy cost. However, a complete and exhaustive study for the usage of Sn in electrochemical reduction of CO2 still does not exist.
Researchers often provide conflicting reports on the role of variables such as cathodic CO2 transport or electrolyte pH. Cathode degradation also has been reported by various researchers in literature but however, disagreement as to the cause of the degradation exists. This thesis presents a fundamental study on the electrochemical reduction of CO2 into HCOO¯ HCOO¯ using a tin plated electrode. Sn was successfully deposited on glassy carbon electrode satisfactorily with a good even surface. The Sn plated electrodes are mechanically stable and give reproducible electrochemical characterizations. The produced Sn electrode is used to investigate the effects of cathode rotating speed, electrolyte pH, and applied cathode potential on the Faradaic
efficiency for HCOO¯. A higher cathode rotating speed is detrimental to the HCOO¯ Faradaic efficiency. CO2 molecules entering the reactor have shorter residence time at higher cathode rotating speeds and some leave without undergoing electrochemical
reaction. Basic conditions are preferable for CO2 reduction to HCOO¯. H2 evolution is prevalent at low pH due to the high amount of available [H+] to be reduced. HCO3¯ may have contributed as a precursor chemical for the formation of HCOO¯. The Faradaic efficiency for producing HCOO¯ increases until it tapers off to a maximum at -1.75 V vs SCE. When the potential is made negative further, the Faradaic efficiency decreasesdue to the enhancement of H2 evolution which is consistent with literature. The Sn plated electrode was found to degrade and strip off during electrochemical reduction likely due to mechanical stress caused by hydrogen embrittlement. When the electrolyte is basic, it is possible that when the Sn-CO2 is formed, the bond between the two does not always break afterwards and thecomplex is brought into the bulk electrolyte. Sn is a potential selective cathode material in electrochemically reducing CO2 into HCOO¯. The roles of several, select, important variables have been made clear for the benefit of future studies. Future studies will also be made aware of the Sn degradation with time during electrochemical reduction. |
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