An artificial photosynthesis process developed at the University of Michigan has achieved 9% efficiency in converting water into hydrogen and oxygen. The technology has been demonstrated to be nearly 10 times more efficient, and markedly lower cost, than comparable solar water-splitting systems

The cost-efficiency of the solar photocatalytic system is largely attributed to the miniaturization of the semiconductor, typically the most expensive part of the device. This self-healing component withstandsA large lens concentrates sunlight onto the water-splitting catalyst. Source: Brenda Ahearn/Michigan Engineering, Communications and Marketing concentrated light equivalent to 160 suns. The device also relies on an indium gallium nitride nanostructure-based photocatalyst that exploits both the higher energy part of the solar spectrum to split water and the lower part to generate reaction-driving heat.

A lens focused sunlight onto an experimental panel just a few inches across during outdoor tests. A simple insulating layer atop the panel keeps the temperature at an optimal 75° C (167° F); the semiconductor catalyst was covered in a layer of water within the panel. The research published in Nature reports solar to hydrogen fuel conversion efficiencies of 9.2%, 7% and 6.2% were documented with the use of pure water, sea water and tap water, respectively.