WHY THIS MATTERS IN BRIEF
Radiation destroys electronics, but what if they could heal themselves to run forever?
A few years ago I talked about a suite of new technologies out of the US that would let the electronics on deep space nano satellites and spacecraft self-heal after they’d been fried by the incessant and damaging radiation that’s found everywhere in space – a very clever trick. Now though, an offshoot of this technology has found an application closer to home after a new type of solar panel has achieved nine percent efficiency in converting water into hydrogen and oxygen through a process known as artificial photosynthesis.
This is a major breakthrough as it is nearly ten times more efficient than previous solar water-splitting experiments, according to a press release by the University of Michigan published on Wednesday.
“In the end, we believe that artificial photosynthesis devices will be much more efficient than natural photosynthesis, which will provide a path toward carbon neutrality,” said Zetian Mi, U-M professor of electrical and computer engineering.
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The team behind the study, led by Mi, was able to shrink the size of the semiconductor, typically the most expensive part of the device, and developed a self-healing semiconductor that can withstand concentrated light equivalent to 160 suns.
Asides from having roots in deep space this technology has the potential to significantly decrease the cost of sustainable hydrogen which is needed for many chemical processes and can be used as a standalone fuel or as a component in sustainable so called Solar Fuels made with recycled carbon dioxide.
The exceptional outcome is the product of two developments. The first is the capacity to focus sunlight without damaging the semiconductor used to capture it. The second method involves splitting water using the higher energy portion of the sun spectrum and heating the reaction by using the lower energy portion of the spectrum.
A semiconductor catalyst, which powers the magic, becomes better with usage and withstands the deterioration that typically occurs when using sunlight to fuel chemical reactions, claims the press release.
“We reduced the size of the semiconductor by more than 100 times compared to some semiconductors only working at low light intensity,” said Peng Zhou, the first author of the study, a U-M research fellow in electrical and computer engineering.
“Hydrogen produced by our technology could be very cheap.”
The semiconductor can survive high temperatures that are punitive to computer chips in addition to enduring high light intensities, and more heat promotes the hydrogen and oxygen to stay apart rather than re-forming their bonds and splitting the water, which speeds up the water-splitting process. The team was able to gather extra hydrogen because of these.
On a silicon surface, nanostructures of indium gallium nitride were grown to form the catalyst. The light was then captured by the semiconductor wafer and transformed into free electrons and holes, which are the positively charged spaces left behind when electrons are released by the light. Nanoscale metal balls that are 1/2000th of a millimeter across are scattered throughout the nanostructures and make use of the electrons and holes in the environment to drive the reaction.
The temperature is maintained at a toasty 75 degrees Celsius, or 167 degrees Fahrenheit, by a straightforward insulating layer on top of the screen. This temperature is heated enough to aid in promoting the reaction while remaining cool enough for the semiconductor catalyst to function effectively.
The effectiveness of converting solar energy into hydrogen fuel in the outside experiment, which had less consistent temperatures and sunlight, was 6.1 percent. However, the system’s efficiency indoors was nine percent.
The team plans to continue improving the efficiency of the technology and to produce ultrahigh-purity hydrogen that can be directly used in fuel cells.
The study was first published in Nature.