A research breakthrough opens up for efficient hydrogen production from solar energy – without using the scarce metal platinum.Mia Halleröd Palmgren
Scientists have introduced a new method to produce hydrogen gas without the scarce and expensive metal platinum. Researchers from Chalmers University of Technology, Sweden, showed how hydrogen can be produced efficiently, sustainably, and at low cost.
They used sunlight, water, and tiny particles of electrically conductive plastic. The process involves quantities of tiny particles of electrically conductive plastic. Immersed in water, the particles interact both with sunlight and with their surroundings, according to Chalmers researcher Alexandre Holmes.
“Developing efficient photocatalysts without platinum has been a long-standing dream in this field. By applying advanced materials design to our conducting-plastic particles, we can produce hydrogen efficiently and sustainably without platinum – at radically lower cost, and with performance that can even surpass platinum-based systems”, said Holmes.
The research team revealed that hydrogen plays a key role in the global pursuit of renewable energy. Although its use produces only water as a by-product, significant challenges remain before hydrogen can be produced both on a large scale and in an environmentally friendly way.
A major challenge is the use of the metal platinum as a co-catalyst when sunlight and water are used to produce hydrogen. The Earth’s reserves of platinum are limited, and extraction is associated with risks to both the environment and to human health. Moreover, the production is concentrated in only a few countries, for example, South Africa and Russia.
Advanced materials design of the electrically conductive plastic
Researchers revealed that the key to the new approach lies in the advanced materials design of the electrically conductive plastic used in the process. This type of plastic, known as conjugated polymers, absorbs light efficiently, but is typically less compatible with water.
By adjusting the material properties at the molecular level, the researchers made the material much more water-compatible.
“We also developed a way to form the plastic into nanoparticles that can enhance the interactions with water and boost the light-to-hydrogen process. The improvement comes from more loosely packed, more hydrophilic polymer chains inside the particles,” added Holmes.
In the reactor at the chemistry laboratory at Chalmers, bubbles of hydrogen gas can be easily seen with the naked eye as they form – showing that photocatalysis is happening efficiently. The research team’s next major step will be to make the hydrogen process work using only sunlight and water, without any added helper chemicals, according to a press release.
Currently, they use vitamin C, which acts as a so-called sacrificial antioxidant. Donating electrons prevents the reaction from stalling, which in the laboratory can show high hydrogen production rates. To realize truly sustainable solar hydrogen, Professor Wang explains, the goal is to split water molecules into hydrogen and oxygen simultaneously, with sunlight and water as the only inputs, as per the release.
Removing the need for platinum in this system is an important step towards sustainable hydrogen production for society.
“Now we are starting to explore materials and strategies aimed at achieving overall water splitting without additives. That will need a few more years, but we believe we are on the right track,” said research leader Ergang Wang, professor at the Department of Chemistry and Chemical Engineering at Chalmers.
