Inspired by photosynthesis, chemical engineers from EPFL (École Polytechnique Fédérale de Lausanne) have created a solar-powered artificial leaf capable of harvesting water from the air and offer hydrogen fuel.
Lead by EPFL chemical engineer Kevin Sivula, the team of researchers have come up with a clever yet easy system that integrates semiconductor-based technology along with novel electrodes that have two main characteristics: they are porous to optimize contact with water present in the air, and transparent to optimize sunlight exposure of the semiconductor coating. The technology is scalable and simple to create.
The study outcomes are reported in the Advanced Materials journal on January 4th, 2023.
When the device is exposed to sunlight, it takes water from the atmosphere and produces hydrogen gas. The team’s novel gas diffusion electrodes are porous, transparent, and conductive, thereby allowing this solar-powered technology to convert water into hydrogen fuel.
“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 Kevin Sivula, Study Principal Investigator.
The newly-developed transparent gas diffusion electrodes are coated with a light-harvesting semiconductor material, serving as an artificial leaf. Their substrate is a 3-dimensional mesh of felted glass fibers. This helps harvest water from the sunlight and air to produce hydrogen gas. The energy of the sunlight has been stored in the form of hydrogen bonds.
“Developing our prototype device was challenging since transparent gas-diffusion electrodes have not been previously demonstrated, and we had to develop new procedures for each step. However, 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” added Marina Caretti, Study Lead Author.
To execute artificial photosynthesis by producing hydrogen fuel from liquid water and sunlight, the researchers employed a device known as a photoelectrochemical (PEC) cell. A PEC cell uses incident light to stimulate a photosensitive material, similar to a semiconductor, immersed in a liquid solution to create a chemical reaction. However, it is difficult to make large-area PEC devices that make use of liquid.
Sivula and his team are focusing their measures on improving the system and determining the ideal fiber size. the ideal pore size, as well as the perfect semiconductors and membrane materials.