|M.Sc Student||Mukha Dina|
|Subject||Enzyme-Based Photoelectrochemical System for Electrical|
|Department||Department of Biotechnology and Food Engineering||Supervisor||Dr. Omer Yehezkeli|
|Full Thesis text|
With increasing energy demands and rising levels of CO2, methods for alternative energy sources are being explored. Bioelectrocatalysis and photoelectrocatalysis are emerging tools for the generation of electrical power or fuels. The natural photosynthesis apparatus utilizes light irradiation for the generation of fuels. Different methods to mimic the photosynthesis process have been developed, where enzymes or inorganic semiconductors were used. While photosystem I and photosystem II have ~100% quantum efficiency, stability issues and high isolation cost limits any further photosystem-based applications. In recent years, “photosynthesis-like” photoelectrochemical cells and photobioeletrochemcial cells were developed. These cells utilize semiconductors for the generation of electrical power or fuels. Enzymes are “super-catalysts”, enabling high selectivity, fast turnover rates, and low activation barriers, while semiconductors can harness solar energy for the generation electron flux. By exploiting the advantages of both the enzymes and the semiconductors we can further design energy generating devices. Here we present a construction of bias-free, donor-free photobioelectrochemical cells for the generation of light-triggered electrical power that utilizes thermophilic bilirubin oxidase from Bacillus pumilus (BpBOD) and bilirubin oxidase from Myrothecium verrucaria (MvBOD) with superior activity and stability at elevated temperatures. Bilirubin oxidases (BOD) were integrated into electrodes and utilized for the bioelectrocatalytic oxygen reduction process. A polymer-based BOD entrapping technique was developed and showed a 2.8 fold current increase of the protein bioelectrocatalytic activity. A pH-independent, positively charged pyrenebetaine linker has been synthesized and utilized, leading to 3-folds bioelectrocatalytic current improvement. Both developed polydopamine/ABTS/MvBOD and the pyrenebetaine/BpBOD biocathodes were further coupled with BiVO4/cobalt-phosphate water oxidation photoanodes to construct biotic/abiotic photobioelectrochemical cells, generating power outputs of 0.74mW/cm2 and 0.85 mW/cm2, respectively. The presented methods are versatile, showing the strength of biotic/abiotic hybrids and can be further used for coupling different redox enzymes with electrodes.