Toward an easily fabricated artificial leaf

Toward an easily fabricated artificial leaf. Photosynthesis, the original green technology, converts solar energy into the chemical energy of nourishing sugars. In the step that crucially depends on sunlight, plants and other organisms use solar energy to break water down into oxygen and hydrogen. Today, research teams worldwide are replicating that ubiquitous natural feat in the lab. One group, led by MIT’s Daniel Nocera, has now devised an artificial leaf with several attractive features: It’s compact, uses inexpensive and easy-to-get materials, works in environments that are not corrosively acidic or basic, and allows wireless operation. The figure shows the oxygen bubbles generated by a 1 × 2 cm artificial leaf immersed in an electrolyte; the device, though, can also function in pure water. The apparatus consists of a piece of silicon covered by catalytic chemicals—on one side is a compound called cobalt oxygen-evolving catalyst; on the other is an alloy...