Scientists participating in Caltech's Chemical Bonding Center project, called "Powering the Planet," are researching the efficient and economical conversion of water and solar energy into the chemical fuels of hydrogen and oxygen. These fuels may be used as a source of energy after the sun goes down and to generate a carbon-neutral or oil-free source of energy scalable to meet future global energy demands.

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MIT's Matthew W. Kanan and Daniel G. Nocera explain how they recently discovered a catalyst that produces oxygen gas from water. Deposited on a conducting glass electrode, the catalyst made from the earth-abundant materials cobalt and phosphate produces oxygen gas from neutral pH water using a relatively low potential at room temperature and pressure. Although the catalytic reaction is not yet fully understood, its discovery moves the center one step closer to reaching its goal of using the sun's energy and water as a renewable energy source. The entire video is available at http://chemicalexplorers.blip.tv/#1150780.

Credit: Stephen E. Lyons, Chemical Explorers, Moreno/Lyons Productions

A snapshot showing the new oxygen catalyst in action in Dan Nocera's laboratory at MIT.

Credit: MIT/NSF

Drawing of a dual photoelectrode assembly proposed by Caltech's "Powering the Planet" Chemical Bonding Center project.

The assembly's cell is designed such that the photoanode will absorb high energy blue light (blue arrow) but not low energy red light (red arrow). The low energy light passes through the photoanode material and is absorbed by the photocathode material.

When sunlight strikes the photocathode in the assembly, the nanorods produce negatively charged electrons (e^-) and positively charged holes. The electrons move to the hydrogen (H₂) catalyst on the surface of the rods, where hydrogen is produced from the electrons and positively charged hydrogen ions or protons (H⁺).