The soaring demand for energy and use of fossil fuels has resulted in the release of vast amount of greenhouse gases and climate change. Developing photoelectrochemical devices for solar fuel production is one of the strategies to address these issues. The use of photosynthetic proteins as photoactive components could potentially generate highly efficient biophotoelectrodes built exclusively from earth-abundant elements, leading to a step change in sustainable solar fuel production. The extreme electron transfer rates, quantum efficiency and large charge separation of the photosynthetic protein complex photosystem 1 delivers the high energy electrons needed for CO2 fixation or H2 evolution in Nature. However, coupling electron transfer between electrodes and photosystem 1 to catalytic processes remains challenging because charge recombination of the reduced electron acceptors with the oxidized form of the electron mediators or with the electrode surface is typically faster than catalysis. The overarching aim of SUPERSET is to demonstrate for the first time the concepts of kinetic barriers and fast hole refilling through electron hopping for preventing charge recombination in scalable biophotoelectrodes and thus enable CO2 reduction and H2 production with semiconductor-free devices. Toward this aim, my specific research objectives will include: (1) Design electron acceptors based on anthraquinones to limit recombination at the electrode by taking advantage of their PCET square scheme mechanism; (2) Modify the surface of electrode by self-assembled monolayers to build a charger barrier to prevent the charge recombination of the reduced electron acceptors with the electrode; (3) Design Osmium/Cobalt-based electron donors with extremely fast electron transfer to enable the refilling of the hole produced by photosystem 1 before recombination takes place; (4) Combine the electron donor and electron acceptor to be channeled to an enzyme for CO2 reduction or H2 production.
