And researchers at the Swiss Ecole Polytechnique Fédérale De Lausanne have found a cheap way to integrate WSe 2 into a solar cell that gives off hydrogen when presented with water.

“Past studies have shown that this material has a great efficiency for converting solar energy directly into hydrogen fuel while also being highly stable,” said the EPFL.

WSe 2 is a 2D material, which is mixed with a solvent and ultrasound-ed at EPFL until it falls into tiny flakes.

A stabiliser converts this into an ink, which is then injected into the boundary between two liquids that do not mix.

“Exploiting this oil-and-water effect, they used the interface of the two liquids as a rolling pin that forced the 2D flakes to form an even and high-quality thin film with minimal clumping and restacking,” said EPFL.

This film can be drained and transferred to a flexible substrate.

Solar-to-hydrogen conversion efficiency was around 1% in a cells made to prove the concept – “already a vast improvement over thin films prepared by other methods”, said EPFL, and the proces looks scalable to commercial levels.

“Considering the stability of these materials and the comparative ease of our deposition method, this represents an important advance towards economical solar-to-fuel energy conversion,” said researcher Kevin Sivula.

‘Self-assembled 2D WSe2 thin films for photoelectrochemical hydrogen production’, Nature Communications.