Artificial Leaf Turns Sunlight Into a Cheap Energy Source

Science magazine

[MIT team led by chemist Daniel Nocera made a presentation a new device] last weekend at the biannual meeting of the American Chemical Society. (...) The new device is a silicon wafer about the shape and size of a playing card. Different catalysts coat each side of the wafer. The silicon absorbs sunlight and passes that energy to the catalysts to split water into molecules of hydrogen (H2) and oxygen (O2). Hydrogen is a fuel that can be either burned or used in a fuel cell to create electricity, reforming water in either case. This means that, in theory, anyone with access to water can use it to create a cheap, clean, and available source of fuel. (...) The silicon absorbs sunlight and passes energetic, negatively charged electrons and positively charged electron vacancies to the catalysts on opposite sides that use them to make H2 and O2. When the device is placed in a clear jar and exposed to sunlight, the setup converts 5.5% of the energy in sunlight into hydrogen fuel. “You literally walk outside, hold it up, and it works,” Nocera says.(...) Nocera didn't reveal the makeup of the new catalyst, as the work is not yet published, and he is in the process of patenting it.