Devices that mimic the natural process of photosynthesis, in which plants use sunlight to turn water and carbon dioxide into energy, could one day help us tackle a number of environmental issues. Scientists have now demonstrated a new type of technology that can not only replicate this process to produce clean hydrogen fuel, but undergo morphological changes during use that makes it become more efficient over time.

The research was carried out by scientists at the University of Michigan (UM) and Lawrence Livermore National Laboratory, who were working with an artificial photosynthesis device previously developed by UM engineer Zetian Mi. The device promised a cleaner form of hydrogen production, which typically involves using natural gas or electrical energy, by instead harnessing sunlight to split fresh and salt water and generate hydrogen for use in fuel cells.

Built from silicon and gallium nitride, materials commonly used in electronics and solar cells, the device offered an impressive three-percent solar-to-hydrogen efficiency, compared to the one-percent efficiency offered by previous devices. It achieved this through a "cityscape" of gallium nitride towers on a silicon backing that turned sunlight into free electrons, which in turn split the water into hydrogen and oxygen.