EPFL scientists have developed a solar-powered device that collects water from the surrounding air and turns it into hydrogen. This technology, which is simple to apply on a large scale, opens perspectives for the creation of “green” fuel.
Engineer and chemist Kevin Sivula presents this concept in the journal Advanced Materials. With his team, he developed a system that combines two key properties: porosity, to maximize contact with atmospheric water, and transparency, to optimize solar exposure of the semiconductor coating.
The innovation is in transparent, porous and conductive gas diffusion electrodes, the Federal Polytechnic School of Lausanne (EPFL) reported on Wednesday.. So they allow this solar technology to convert gaseous water in the air into hydrogen.
The invention was directly inspired by photosynthesis, the natural process by which plants absorb CO2 and water from the environment and convert these molecules into sugar and oxygen using solar energy. Scientists have been trying to reproduce this phenomenon in the laboratory for a long time.
The solar-powered device created by EPFL collects water from the surrounding air and turns it into hydrogen. [Alain Herzog – EPFL]
“We’ve created a tiny blue disk called a porous photocathode that can generate hydrogen using only sunlight and moisture in the air,” the lab’s doctoral student Benjamin Goldman, of EPFL in Molecular Engineering, said Wednesday. at 7:30 p.m
Instead of producing electrodes in the traditional way, with opaque layers, the scientists used a substrate made of three-dimensional glass fibers. The plates are then coated with a transparent film of fluorine-enhanced tin oxide. A material known for its excellent conductivity, strength and ease of mass production.
These first steps result in a transparent, porous and permeable plate, which is important to maximize contact with water molecules present in the air, as well as allowing photons to pass through. Then the plate is covered with another coating: a thin film of light-absorbing semiconductor materials.
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Hydrogen of the future?
This “green” hydrogen is not similar to hydrogen obtained from fossil materials such as petroleum. “I think this is the future of hydrogen as a way to store energy in fuel or chemical form,” Kevin Sivula comments at 7:30 p.m.
This technology is also simple to manufacture and apply on a large scale. Therefore, the consequences can be huge: “If we can produce this hydrogen cleanly, tomorrow’s fuels will only need the hydrogen and oxygen that are present in the air,” emphasizes Benjamin Goldman.
“So we can release only water into the atmosphere, not more carbon dioxide or other greenhouse gases,” he said.
Productivity is still moderate
As it is, the wafer can produce excess hydrogen when exposed to the sun. The scientists then made a small chamber with the plate, as well as a membrane to separate the produced gas.
“Developing our prototype was challenging because transparent electrodes with gas diffusion have never been demonstrated before,” Marina Caretti, the author responsible for the study, is quoted in a press release.
According to EPFL, the scientists are now aiming to optimize their prototypes, whose performance remains “modest” for now. This will involve determining the ideal size of fibers and pores, as well as the most suitable materials.
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