The next challenges the team intends to tackle are to further improve the efficiency and to achieve ultrahigh purity hydrogen that can be directly fed into fuel cells
A new press report recently published by the University of Michigan highlighted that through the process of artificial photosynthesis, a first of its kind solar panel has managed to achieve nine percent more efficiency than the earlier solar-water splitting experiments. Through artificial photosynthesis, the efficiency has been achieved by converting water into oxygen and hydrogen. The report further added that the process turned out to be a huge achievement because it is almost ten times more efficient than the previous experiments.
According to a report of Interesting Engineering, Zetian Mi, U-M professor of electrical and computer engineering has spearheaded the project and he successfully compressed the size of the semiconductor, which is known to be the most priciest part of the product. Moreover, he also unleashed a self-healing semiconductor that has the ability to combat concentrated light equivalent to 160 suns. Mi told Interesting Engineering, “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.”
The exclusive report by Interesting Engineering also mentioned that 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 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. There is a second method, which 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.
And the second is using both the higher energy part of the solar spectrum to split water and the lower part of the spectrum to provide heat that encourages the reaction. The magic is enabled by a semiconductor catalyst that improves itself with use, resisting the degradation that such catalysts usually experience when they harness sunlight to drive chemical reactions. Its self-healing property enables it to withstand light equivalent to 160 suns. In addition to handling high light intensities, it can thrive in the high temperatures that are punishing to computer semiconductors. Higher temperatures speed up the water splitting process, and the extra heat also encourages the hydrogen and oxygen to remain separate rather than renewing their bonds and forming water once more. Both of these helped the team to harvest more hydrogen.
For the outdoor experiment, Zhou set up a lens about the size of a house window to focus sunlight onto an experimental panel just a few inches across. Within that panel, the semiconductor catalyst was covered in a layer of water, bubbling with the hydrogen and oxygen gasses it separated. The catalyst is made of indium gallium nitride nanostructures, grown onto a silicon surface. The gallium nitride captures the light, converting it into free electrons and holes—positively charged gaps left behind when electrons are liberated by the light. Those nanostructures are peppered with nanoscale balls of metal, 1/2000th of a millimeter across, that use those electrons and holes to help direct the reaction.
(excerpts from Michigan Engineering Media Release- University of Michigan)