By using a polymeric film that protects photovoltaic cells, the Rice University researchers produce solar hydrogen directly in water.
The new low-cost hydrogen production system is inspired by artificial leaves.
Researchers from Rice University have designed an efficient and low-cost device for the production of solar hydrogen. And for this they resorted to the last bet of the photovoltaic industry : perovskite, artificial oxides whose crystalline structure mimics that of the natural mineral.
Researchers have bonded a perovskite layer with cobalt phosphide (CoP) -based catalytic electrodes, in a single module. Once in the water and illuminated, the module produces electricity from the cells and current flows to the electrodes. Here the electrolysis of water molecules takes place, producing hydrogen and oxygen. In general, the entire reaction, from sunlight to hydrogen, has an efficiency of 6.7%.
The module, therefore, is a self-sufficient fuel producer which, according to the researchers, has the advantage of being easy to produce.
The concept is basically similar to that of an artificial leaf. What we have is a built-in module that transforms sunlight into electricity, which in turn triggers an electrochemical reaction. In this way, it uses water and sunlight to make chemical fuels.
The solar cells in the perovskite have achieved an efficiency of over 25%, but the materials are expensive and tend to “stressed” by moisture and heat. For this reason, researchers have replaced the more expensive components, such as platinum, with alternative materials, such as carbon.
However, according to the researchers, the key component is not the perovskite, but the polymer that encapsulates it (a thin film of Surlyn), protecting the module and allowing it to submerge for long periods. The molded film allows light to reach the solar cell while protecting it and acting as an insulator between the cells and the catalytic electrodes.
With an intelligent system design, you can potentially create a self-sufficient circuit. Even when there is no sunlight, energy stored in the form of chemical fuel can be used. You can put hydrogen and oxygen products in separate tanks and incorporate another module to convert those fuels into electricity.
The research was published in ACS Nano.
More information: news.rice.edu