Scientists at Ecole Polytechnique Fédérale de Lausanne (EFPL) in Switzerland have developed a cost-effective new method for converting and storing solar energy by making free hydrogen fuel.

The team thinks their liquid-liquid method can be scaled up on a commercial level. The study paper has been published in Nature Communications.

Direct Solar Hydrogen Production Panel Sample.  Click image for more info.

Direct Solar Hydrogen Production Panel Sample. Click image for more info.

Storing solar energy as hydrogen could be a promising way for developing comprehensive renewable energy systems. So far traditional solar panels can be used to generate an electrical current that splits water molecules into oxygen and hydrogen, the latter being considered a form of solar fuel. But, the cost of producing efficient solar panels makes water-splitting technologies too expensive to commercialize.

Many different materials have been considered for use in direct solar-to-hydrogen conversion technologies but “2-D materials” have recently been identified as promising candidates. In general these materials – which famously include graphene – have extraordinary electronic properties. However, harvesting usable amounts of solar energy requires large areas of solar panels, and it is notoriously difficult and expensive to fabricate thin films of 2-D materials at such a scale and maintain good performance.

Kevin Sivula and colleagues at EPFL addressed this problem with an innovative and very low cost method that uses the boundary between two non-mixing liquids. The researchers focused on one of the best 2-D materials for solar water splitting called “tungsten diselenide”. Past studies have shown that this material has a great efficiency for converting solar energy directly into hydrogen fuel while also being highly stable.

Before making a thin film of tungsten diselenide, the scientists first had to achieve an even dispersion of the material. To do this, they mixed the tungsten diselenide powder with a liquid solvent using sonic vibrations to “exfoliate” it into thin, 2-D flakes, and then added special chemicals to stabilize the mix. Developed by Sivula’s lab in 2014, this technique produces an even dispersion of the flakes that is similar to an ink or a paint.

The researchers then used an out-of-the-box innovation to produce high-quality thin films: they injected the tungsten diselenide ink at 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 2-D flakes to form an even and high-quality thin film with minimal clumping and restacking. The liquids were then carefully removed and the thin film was transferred to a flexible plastic support, which is much less expensive than a traditional solar panel.

The thin film produced in the new process was tested and found to be superior in efficiency to films made with the same material but using other comparable methods. At this proof-of-concept stage, the solar-to-hydrogen conversion efficiency was around 1% -already a vast improvement over thin films prepared by other methods, and with considerable potential for higher efficiencies in the future.

Sivula said, “It is suitable for rapid and large-area roll-to-roll processing. 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.”

Factory ready its not. But its real, works and is very low cost. There is a long way to go for commercial panels, but skipping the entire electric generation and electrolysis steps and going direct to hydrogen fuel is quite an incentive for more research and development. The hydrogen economy folks have to be thrilled.


1 Comment so far

  1. Roy Long on July 8, 2015 3:52 PM

    This has potential but still is in the lab. I’m still fond of HyperSolar’s technology to split water with the sun. They just achieved a 1.4V breakthrough and they are much closer to commercialization. Their penny stock is publicly traded under the symbol HYSR and their website is

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