Solar hydrogen may be produced efficiently without platinum

Researchers have a new way to produce hydrogen gas without platinum, using sunlight, water and particles of plastic.

Chalmers University of Technology, Sweden, say the technique shows how hydrogen can be produced efficiently, sustainably and at low cost.

Hydrogen plays a key role in the global pursuit for renewable energy. Although its use produces only water as a by-product, significant challenges remain before hydrogen can be produced both on a large-scale and in an environmentally friendly way.

A major challenge is the use of platinum as a co-catalyst.

Efforts to overcome the challenge have been underway for several years in the Chalmers research group.

The process involves quantities of tiny particles of electrically conductive plastic. Immersed in water, the particles interact both with sunlight and with their surroundings.

The key to the new approach lies in advanced materials design of the electrically conductive plastic used in the process. This type of plastic, known as conjugated polymers, absorbs light efficiently, but is typically less compatible with water.

By adjusting the material properties at the molecular level, the researchers state that they made the material much more water compatible.

They say that with as little as one gramme of the polymer material, they can produce 30L of hydrogen in one hour.

The next major step will be to make the hydrogen process work using only sunlight and water, without any added chemicals.

Currently, they use vitamin C, which acts as a so-called sacrificial antioxidant. By donating electrons, it prevents the reaction from stalling, which in the laboratory can show high hydrogen production rates.

To realise truly sustainable solar hydrogen, the goal is to split water molecules into hydrogen and oxygen simultaneously, with sunlight and water as the only inputs.