The artificial leaf looks nothing like the natural leaf that it mimics, but its inputs and outputs are the same. Made of silicon, electronics, and various catalysts that spur chemical reactions within the device, the artificial leaf uses sunlight to break water into hydrogen and oxygen which can then be used to create electricity in a separate fuel cell. Placed in a gallon of water and left in the sun, these artificial leaves could provide a home in the developing world with basic electricity for a day, Nocera said.