The journal Nature Photonics published an article that might hold the solution to storing solar energy regardless of the time of day. The technology that transforms light energy into hydrogen is developed and presented by a team of scientists from EPFL. Kevin Sivula and his team aimed to develop an economically viable method to produce solar hydrogen. The device that they prototyped uses two very basic ingredients- water and rust.
Converting solar energy into hydrogen has begun nearly five decades ago. At EPFL, Michael Gratzel was the one who introduced the topic by joining forces with a colleague from University of Geneva. They invented the photoelectrochemical tandem solar cell, which produces hydrogen from water by using dye-sensitized solar cell, also Gratzel’s invention, and an oxide-based semiconductor.
The device has two layers that get stimulated by light to produce electrons. An oxide semiconductor forms oxygen, while a dye-sensitized cell liberates the hydrogen. All this makes the device completely self-sufficient.
According to Sivula, currently existing technology might achieve impressive efficiency, however at quite a high cost. In this respect, the team from EPFL aimed to test only cheap materials, which proved to be a difficult task, but possible for them to accomplish.
The prototype has efficiency of only 1.4- 3.6 %, however the team is convinced that they can do better. Developing their concept and using only iron oxide they hope to achieve efficiency of up to 10% for less than $80 per square meter in the next 5 years.
The iron oxide, used in the prototype, is nonstructured, enhanced with silicon oxide and covered with a very thin layer of aluminum and cobalt oxide in order to optimize the electrochemical properties of the material. The second part of the device is composed of a dye and titanium dioxide, which allows the electrons that are transferred by the iron oxide to gain sufficient energy and extract hydrogen from water.
Sivula predicts that this technology will reach up to 16% efficiency at a very low cost. This will allow cheap and affordable storage of solar energy and will place it high on the list of viable renewable energy sources.
Via: Science Daily