Research on artificial photosynthesis represents a step forward towards green hydrogen

How can we produce clean hydrogen without burning fossil hydrocarbons and other non-renewable energy sources? This can be done via photoelectrochemical or artificial photosynthesis. It uses sunlight and water, like photosynthesis, to obtain hydrogen without producing harmful emissions. A group of researchers from the Faculty of Physics at Trent University focuses precisely on this approach.

This study is published in the Journal Carbon.

One of the most innovative aspects of their research projects is the use of photocatalysts (semiconductor materials) based on two-dimensional materials, particularly carbon nitride graphic acid (G-C3N4). This material is lightweight and sustainable and is used to break the chemical bonds of water molecules to produce hydrogen.

This study shows that when used in the form of a single atomic layer, these photocatalysts offer superior performance compared to previously tested thick, less ordered structures. This finding may open up ways to use these materials more efficiently in the production of green hydrogen.

Hydrogen is considered one of the most promising solutions for energy transitions. However, most hydrogen produced today is produced through a “steam reform” method in which methane (fossil fuel) is heated to high temperatures. A process that is not completely sustainable. Instead, the Trent-based research team focuses on hydrogen production via photoelectrochemical cells.

This is a clean process that uses hydrocarbons and other non-renewable energy sources to break down chemical bonds in water molecules to produce hydrogen.

“Graphite-nitride-based graphite-based graphite is suggested as a potential photocatalyst. When contacted with water, the semiconductor absorbs visible sunlight and converts it into chemical energy, allowing the movement of electrons within the material. Little is known about these mechanisms.

“By studying the formation and propagation of excitons (bound electron hole pairs) produced by the sunlight of carbon nitride formed by a single layer of atoms, we have noticed that there is a very low velocity and photocatalytic movement thanks to the combined motion involving oscillations of the atoms.”

The authors of this study were surprised by the results. Electrons are more than 2000 times smaller than the atoms in the photocatalyst. Therefore, they move faster just as a group of insects (electrons) move around a person (atom). However, this does not occur with carbon nitride. It’s as if a group of insects agrees with a person to walk with their arms like a couple until they meet hydrogen ions together.

“When this happens,” explains research coordinator Matteo Calandra. “Atoms are passed through electrons that bind to hydrogen ions.

The researchers’ work continues to run numerical simulations on a database of over 5,000 accessible materials, perform computational screenings, and identify catalysts that are superior to current catalysts.

“We hope that this research will lead to powerful innovations in the production of hydrogen from photoelectrolytic cells. This methodology allows us to systematically identify better performance materials and accelerate the progress of green hydrogen production.”

This project represents an important step towards energy sustainability.