EPFL researchers have developed a solar cell-powered device that harvests water from the surrounding air and converts it into hydrogen. This technology, which is easy to implement on a large scale, opens up opportunities to create “green” fuel.
Engineer and chemist Kevin Sivula presents this concept in the journal “Advanced Materials”. Together with his team, he developed a system that combines two key characteristics: porosity, to maximize contact with atmospheric water, and transparency, to optimize sun exposure of the semiconductor coating.
The innovation lies in the gas diffusion electrodes, transparent, porous and conductive, indicated the Federal Polytechnic School of Lausanne (EPFL) on Wednesday in. They thus allow this solar technology to convert water present in the air in gaseous form into hydrogen.
The invention is directly inspired by photosynthesis, a natural process in which plants absorb CO2 and water from their environment and convert these molecules into sugar and oxygen using the sun’s energy. Scientists have long tried to reproduce this phenomenon in the laboratory.
The device created by EPFL runs on solar energy, harvesting water from the surrounding air and converting it into hydrogen. [Alain Herzog – EPFL]
an artificial leaf
“We have created a small blue disk, which is called a porous photocathode, which is only able to create hydrogen by using sunlight and the moisture present in the air”, summarizes Benjamin Goldman, PhD student at the Laboratory. in Molecular Engineering from EPFL, Wednesday at 7:30 p.m.
Instead of making electrodes in the traditional way, with opaque layers, the researchers used a substrate consisting of a three-dimensional mesh of glass fibers. Afterwards, the plates are coated with a transparent film of fluoride-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 that is essential to maximize contact with water molecules present in the air as well as to allow photons to pass through. The plate is then covered with another coating: a thin film of semiconductor materials that absorbs light.
>> The explanations in English about the operation of this artificial leaf:
The hydrogen of the future?
This “green” hydrogen is not similar to that produced by fossil materials such as oil. “I think this is the future of hydrogen, as a fuel or a way to store energy in chemical form”, comments Kevin Sivula at 19.30.
This technology is also simple to manufacture and implement on a large scale. Its implications can therefore be enormous: “If we manage to produce this hydrogen in a clean way, tomorrow’s fuels will only need hydrogen and oxygen present in the air”, emphasizes Benjamin Goldman.
“We would thus only be able to release water into the atmosphere and no longer carbon dioxide or other greenhouse gases,” he adds.
Yield still modest
As it is, the wafer can already produce hydrogen when exposed to the sun. Researchers have further developed a small chamber containing the plate, as well as a membrane to separate the gas produced.
“It was difficult to develop our prototype because the transparent electrodes with gas diffusion had never been the subject of a previous demonstration”, explains Marina Caretti, author in charge of the study, quoted in the press release.
The researchers now intend to optimize their prototype, whose performance remains “modest” for now, according to EPFL. This will include determining the ideal size of fibers and pores, as well as the most suitable materials.
>> The explanations from Céline Brichet at 19.30: