UC San Diego

Renewable energy-driven small molecule conversion and synthesis is a sustainable strategy to simultaneously produce commodity chemicals and achieve molecule valorization. Powered by renewable energy sources, photocatalysis and electrolysis have emerged as efficient and green methods for small molecule conversion, such as photocatalytic/electrocatalytic carbon dioxide reduction reaction (CO2RR) and biomass oxidation. Following the general introduction of renewable energy-driven small molecule conversion and synthesis in Chapter 1, Chapter 2 demonstrates an axial ligation strategy for cobalt phthalocyanine (CoPc) molecular catalyst to enhance its electrocatalytic carbon dioxide (CO2) efficiency. After coordinating with axial pyridine (CoPc-py) and imidazole (CoPc-im) ligands, the CoPc-py and CoPc-im catalysts display an elevated performance for converting CO2 to CO compared to bare CoPc catalyst. Chapter 3 to Chapter 5 are mainly focusing on ethylene glycol (EG) oxidation reaction (EGOR) to upcycle polyethylene terephthalate (PET) plastic waste via photocatalytic and electrocatalytic methods. Chapter 3 reveals that the photocatalytic EGOR pathway is determined by EG concentration over a MoS2/g-C3N4 photocatalyst. In addition, with the developed MoS2/g-C3N4 photocatalyst, the real-world PET plastic waste can be upcycled into multiple value-added products driven by sunlight under natural conditions. In Chapter 4, a Ni-based catalyst (NiCu/NF) was developed via electrodepositing copper (Cu) species on Ni foam (NF) to upcycle PET waste to valuable products via electrocatalysis. In addition, the role of Cu in promoting Ni-based catalyst dynamic evolution during the electrocatalysis process was well investigated via a combination of ex-situ and in-situ characterization techniques. Lastly, Chapter 5 centers on mining the carbon intermediates in plastic waste upcycling for constructing C-S bonds. This chapter demonstrates an innovative strategy to intercept the in-situ formed electrophiles during the PET plastic waste electrooxidation process via reacting with nucleophilic species. With this strategy, sulfonate was efficiently synthesized with the PET waste and sulfite as C and S sources, respectively.