Researchers at the École Polytechnique fédérale de Lausanne (EPFL) have invented a solar-powered device that is capable of harvesting water from the air for conversion into hydrogen fuel.

The research team at EPFL has developed the system by combining a semiconductor-based technology with novel electrodes.

These electrodes allow the device to maximize contact with water in the air. Since it is transparent, it maximizes sunlight exposure of the semiconductor coating.

“To realize a sustainable society, we need ways to store renewable energy as chemicals that can be used as fuels and feedstocks in industry. Solar energy is the most abundant form of renewable energy, and we are striving to develop economically competitive ways to produce solar fuels,” said Sivula, Principal Investigator of the study.

The researchers said they took inspiration for their device from the process of photosynthesis in plants which converts sunlight into chemical energy using carbon dioxide from the air.

The device’s transparent gas diffusion electrodes when coated with a light-harvesting semiconductor material act like an artificial leaf — performing artificial photosynthesis which is able to store the sun’s energy in the form of hydrogen bonds.

The researchers said the semiconductor-based technology is scalable and easy to prepare.

“Since each step is relatively simple and scalable, I think that our approach will open new horizons for a wide range of applications starting from gas diffusion substrates for solar-driven hydrogen production,” Marina Caretti, lead author of the work, said.

The team of researchers as well as other research groups had previously shown that it is possible to perform artificial photosynthesis by generating hydrogen fuel from liquid water and sunlight using a device called a photoelectrochemical (PEC) cell.

A PEC cell is generally known as a device that uses incident light to stimulate a photosensitive material, like a semiconductor, immersed in a liquid solution to cause a chemical reaction.

But this process posed practical difficulties.

The team said they wanted to show that the PEC technology can be adapted for harvesting humidity from the air instead, which led to the development of their new gas diffusion electrode.

The researchers are currently focusing on optimizing the system to advance this technology and develop new ways to convert hydrogen into liquid fuels.

In December 2022, researchers from EPFL developed a method that improves both power conversion efficiency and stability of solar cells based on pure iodide as well as mixed-halide perovskites.

Last September, researchers at the University of Melbourne developed a way to generate hydrogen directly from the air, eliminating the dependency on freshwater resources.

Image: EPFL