Storing solar energy as hydrogen is a promising way for developing comprehensive renewable energy systems. To accomplish this, 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.
However, the cost of producing efficient solar panels makes water-splitting technologies too expensive to commercialize. EPFL scientists have now developed a simple, unconventional method to fabricate high-quality, efficient solar panels for direct solar hydrogen production with low cost. The work is published in Nature Communications.
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 cheap 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 it, 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 (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 like this 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.
More importantly, this liquid-liquid method can be scaled up on a commercial level. "It is suitable for rapid and large-area roll-to-roll processing," says Kevin Sivula. "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."
This work was funded by the Swiss Competence Centers for Energy Research (SCCER Heat and Electricity Storage) and the European Commission's Framework Project 7 (FP7) through a Marie-Curie Intra-European Fellowship (COCHALPEC).
Yu X, Prévot MS, Guijarro N, Sivula K. Self-assembled 2D WSe2 thin films for photoelectrochemical hydrogen production. Nature Communications 01 July 2015. DOI: 10.1038/ncomms8596
Nik Papageorgiou | EurekAlert!
Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging
24.04.2017 | Pohang University of Science & Technology (POSTECH)
Wonder material? Novel nanotube structure strengthens thin films for flexible electronics
24.04.2017 | University of Illinois College of Engineering
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences