ScotCHEM Lecture: A Complete Artificial Photosynthesis at High Efficiency

The artificial leaf accomplishes a solar fuels process that captures the elements of photosynthesis – the splitting of water to hydrogen and oxygen using light, from neutral water, at atmospheric pressure and room temperature. These conditions are met owing to the development of water splitting catalysts of the elements of Mn, Co and Ni that are self-healing; the design principles for self-healing catalysis will be presented. The self-healing catalysts are coated on a silicon wafer in a buried junction configuration, which enables light harvesting and charge separation to be coupled to catalysis under simple conditions. We have advanced the design of the artificial leaf by utilizing the hydrogen from the artificial leaf and combining it with carbon dioxide to make liquid fuels. Using the tools of synthetic biology, a bio-engineered bacterium has been developed to convert carbon dioxide, along with the hydrogen produced from the artificial leaf, into biomass and fusel alcohols. This hybrid microbial | artificial leaf system scrubs 180 grams of CO2 from air, equivalent to 230,000 litres of air per 1 kWh of electricity. Coupling this hybrid device to existing photovoltaic systems leads to unprecedented solar-to-biomass (10.7%) and solar-to-liquid fuels (6.2%) yields, which greatly exceeding natural photosynthetic systems.