Cost-Effective Catalysts for the Electrochemical and Photoelectrochemical Reduction of Carbon Dioxide

  • Author / Creator
    Zhang, Sheng Nian
  • The growing consumption of fossil resources has rapidly depleted fuel availability and increased CO2 emission, which presents two of the most prominent crises in the modern era. CO2 reduction reaction (CO2RR) at ambient conditions using electrochemical (EC) and photoelectrochemical (PEC) methods are promising ways to reducing CO2 emission while producing storable fuels and chemicals that can be later consumed on demand. To date, highly selective electrochemical conversion of CO2 to CO, an essential precursor in Fischer-Tropsch processes, require heavily on the use of precious metals while operating at a significant high overpotential. Photocathode-driven PEC conversion of CO2 can achieve one step conversion of solar energy to chemical energy, but issues such as toxicity, poor selectivity and stability, large external bias potential remain unresolved. On the other hand, photoanodes are well studied in water splitting researches, which can be integrated with CO2RR electrocatalysts in a photoanode-driven CO2 reduction system.
    In this thesis, a novel, simple, and low-cost Cu2O-SnO2 core-shell nanocrystal electrocatalyst was first designed. The electrocatalyst achieved over 90% Faradaic efficiency for CO2-to-CO conversion at overpotentials of 890 mV and 390 mV in 0.1 M KHCO3 and 0.5 M KHCO3, respectively, which are comparable to those achieved on the precious metals. To further reduce the cell overpotential, a photoanode-driven PEC system is demonstrated through combining Cu2O-SnO2 electrocatalyst as a dark cathode and an n-Si/Ni photoanode, achieving a 400-mV reduction in overpotential at 5 mA cm-2 when compared to an electrochemical system. The designed PEC cell obtained a photo-assisted efficiency (๐œ‚๐‘ƒ๐ด๐ธ) of 3.5% while operated over 12 hours with minor degradation.

  • Subjects / Keywords
  • Graduation date
    Fall 2019
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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