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A photoreactor is capable of converting sunlight into chemical energy at low cost. After promising initial tests, the goal is now to develop a photocatalyst that can efficiently produce hydrogen.
Producing hydrogen and green fuels from your own roof isnt as crazy an idea as it sounds: Researchers at the Karlsruhe Institute of Technology and the University of Toronto have developed a photoreactor with technology that recreates photosynthesis. For this, a photocatalyst is needed, which when irradiated with photons converts radiant energy into chemical energy, and a photoreactor.
Progress has already been made in the development of the catalysts. “Several photocatalysts are currently known,” explains Paul Kant, from KITs Institute for Microprocess Engineering (IMVT). “They can be used, for example, to split water into hydrogen and oxygen, but climate-neutral fuels can also be produced from water and carbon dioxide.”
In Karlsruhe, Kant and his team therefore focused on photoreactors. These must contain the starting materials for the chemical reaction and carry enough light to the photocatalyst regardless of the angle of insolation from the sun. Ideally, the photosynthesis modules do not have to follow the position of the sun.
With the help of computer-aided geometry optimization, the researchers managed to develop a kind of wavy metal structure with a tube at the pointed end that carries as much light as possible into the reactor. “It is also important that the structure of the photoreactor and the material used ensure optimal operating conditions for the photocatalyst, such as the right temperature or the right intensity when light is absorbed by the photocatalyst,” explains Kant.
The final product consists of microstructured polymer panels. To allow for light reflection, the developers coated these polymeric components with aluminium. The system has already been tested on a laboratory scale.
Based on the photon-induced redox reaction of potassium hexacyanidoferrate(III), the Karlsruhe team was able to demonstrate a UV-vis photocatalytic efficiency of 5.8 percent. Compared to previously used quartz glass capillaries, this is a four-fold improvement. This level of efficiency is 62% of the theoretical limit, according to the scientists in their publication in the scientific journal Joule .
In further work, the Karlsruhe team will collaborate with researchers at the University of Toronto to develop a reactor-adapted photocatalyst capable of splitting water into hydrogen and oxygen very efficiently. The catalyst will then be integrated into the reactor and submitted for series production.
Using low-cost materials and geometric shapes that can be made with common production machines, the researchers anticipate a price of US$22 per square meter of photoreactor module surface area. The system is conceivable in rooftop applications and in ground-mounted systems, says the KIT statement.
In addition, the photoreactor module can also produce drinking water. However, the study does not report whether such a system can produce enough drinking water for a household. |
