Sound waves can set electrolysis systems into high-frequency vibrations and thus greatly increase the hydrogen yield. Such a system does not require expensive electrodes made of platinum metals and alkaline or acidic electrolyte solutions.
Melbourne (Australia). Green hydrogen is produced by splitting water molecules into oxygen and hydrogen via electrolysis. In order to increase the efficiency of this process, electrodes made of expensive platinum metals are usually used. In addition, alkaline or strongly acidic electrolyte solutions are used, which cause rapid corrosion of the systems.
Other electrolysis systems that use neutral electrolytes and much cheaper electrode materials have so far been much less efficient because the gas collects on the electrodes and makes further reactions more difficult. Now, scientists at RMIT University have improved such an electrolysis system using sound waves so that it can split water with high efficiency.
Electrolysis system vibrated
According to their publication in the journal Advanced Energy Materials , the researchers led by Yemima Ehrnst tested what happens when an electrolysis system with neutral electrolytes and inexpensive electrode materials is made to vibrate with high-frequency sound waves. To do this, they developed an electrochemical reaction cell based on the piezoelectric material lithium niobate, which can generate high-frequency sound and surface waves in the liquid medium. Sodium phosphate was used as the electrolyte.
Hydrogen yield 14 times higher
Measurements showed that the vibrations in the liquid medium of the electrochemical cell increase the hydrogen yield of the electrolysis system by a factor of 14. As Leslie Yeo explains, this is primarily because the high-frequency vibrations prevent gas bubbles from forming on the electrodes.
“This is an important advantage for the conductivity and stability of the electrodes.”
In addition, the sound waves also affect the bonding and structure of the water molecules by loosening or even severing the hydrogen bonds. This creates free water molecules that can be split off electrochemically more easily. According to Amgad Rezk, this makes the extraction of hydrogen much easier.
“The sound waves make it much easier to extract hydrogen from the water. This eliminates the need for corrosive electrolytes and expensive platinum or iridium electrodes.”
Efficient and cheap hydrogen production
According to the developers, their technology enables efficient and inexpensive hydrogen production without corrosive electrolytes and platinum electrodes.
“Our approach is a practically applicable and cost-effective way to generate green hydrogen using cheap, widely available electrodes that are considered to be ineffective.”
The researchers are currently working on further optimizing the vibration module and integrating it into conventional electrolysis systems.
“We expect that the yield can be improved even further with higher current densities.”