EPFL scientists have developed a solar-powered device that extracts water from the surrounding air and converts it into hydrogen. This technology, which can be easily implemented on a large scale, opens up perspectives for the production of “green” fuels.
Engineer and chemist Kevin Sivula introduces 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 the semiconductor coating’s insolation.
The innovation lies in the gas diffusion electrodes, which are transparent, porous and conductive, as the Federal Polytechnic School in Lausanne (EPFL) pointed out on Wednesday a statement. They enable this solar technology to convert water, which is present in gaseous form in the air, into hydrogen.
The invention is directly inspired by photosynthesis, a natural process by which plants absorb CO2 and water from their environment and use the sun’s energy to convert these molecules into sugar and oxygen. Scientists have long tried to reproduce this phenomenon in the laboratory.
The device developed by EPFL, which is powered by solar energy and extracts water from the surrounding air and converts it into hydrogen. [Alain Herzog – EPFL]
an artificial leaf
“We have created a small blue disk, called a porous photocathode, capable of generating hydrogen using only sunlight and the moisture present in the air,” summarizes Benjamin Goldman, a PhD student at EPFL’s Molecular Engineering Laboratory , on Wednesday together at 7:30 p.m
Instead of making electrodes the traditional way with opaque layers, the scientists used a substrate composed of a three-dimensional mesh of glass fibers. The panels are then coated with a transparent film of fluorine-reinforced tin oxide. A material known for its excellent conductivity, robustness and ease of mass production.
These first steps result in a transparent, porous and conductive sheet, essential to maximize contact with the water molecules present in the air and allow photons to pass. The plate is then covered with another coating: a thin film of semiconductor materials that absorb light.
>> The explanations in English of how this artificial leaf works:
The hydrogen of the future?
This “green” hydrogen is not comparable to that produced from fossil materials such as petroleum. “I think this is the future of hydrogen, as a fuel or as a way to store energy in chemical form,” comments Kevin Sivula at 7:30 p.m.
This technology is also easy to manufacture and implement on a large scale. The impact could therefore be enormous: “If we manage to produce this hydrogen in a clean way, the fuels of tomorrow will only need hydrogen and oxygen in the air,” emphasizes Benjamin Goldman.
“This means that we would only be releasing water into the atmosphere and no more carbon dioxide or other greenhouse gases,” he adds.
Yield still modest
In any case, the wafer can already produce hydrogen when it is exposed to the sun. Scientists have further developed a small chamber that contains the plate and a membrane to separate the gas produced.
“It was difficult to develop our prototype because the transparent gas diffusion electrodes have never been the subject of a previous demonstration,” explains Marina Caretti, lead author of the study, quoted in the press release.
The scientists now want to optimize their prototype, the performance of which, according to EPFL, will remain “modest” for the time being. This includes determining the ideal fiber and pore size and the most suitable materials.
>> Céline Brichet’s statements at 7:30 p.m.:
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