"Artificial Leaf" Research Paper

Recent Breakthrough - “Artificial Leaf” In the past 3 million years, the levels of atmospheric carbon dioxide have been at their highest ever. With the more relatively recent beginning of the Industrial Age, the amount of clean, breathable air that humanity depends upon for survival, has, as a response to the Era, decreased. The increase in carbon emissions and the increasing dependence upon fossil-fuels for energy has led to a global race for the creation of a carbon-neutral, renewable energy source. Scientists with the U.S. Department of Energy have created this new source of energy from a project known as “Artificial Leaf”. The project, “Artificial Leaf”, is similar to normal green plants in that it carries out a form of photosynthesis through a chemical reaction involving sunlight and the molecules found in water, hydrogen and oxygen. Peidong Yang, a chemist working on the initial project, describes the Leaf as an “artificial photosynthetic system composed of two semiconductor light absorbers, an artificial layer for charge transport, and spatially separated co-catalysts” that “very much resemble an artificial forest”. Peidong Yang continues to describe the process of energy transformation as an integration of “our nanowire nanoscale heterostructure into a functional system that mimics the integration in chloroplasts and provides a conceptual blueprint for better solar-to-fuel conversion efficiencies in the future. When sunlight is absorbed by pigment molecules in a chloroplast, an energized electron is generated that moves from molecule to molecule through a transport chain until ultimately it drives the conversion of carbon dioxide into carbohydrate sugars. This electron transport chain is called a "Z-scheme". Yang and his colleagues also use a Z-scheme in their system only they deploy two Earth abundant and stable semiconductors, silicon and titanium oxide, loaded with co-catalysts and with an ohmic contact inserted between them. Silicon was used for the