Science & Technology (Commonwealth Union) – The search for natural sources of environmentally friendly energy remains a key focus across the world.
Researchers have formed a technique that uses liquid metals and sunlight to generate clean hydrogen from both freshwater and seawater.
This approach enables the extraction of hydrogen molecules from water while bypassing many limitations of current hydrogen production methods. It opens a promising new path for generating green hydrogen as a sustainable energy source.
For years, hydrogen has been a key target in the quest for clean energy. Researchers and industries worldwide have been searching for cost-effective ways to produce green hydrogen consistently, with the goal of powering sectors like energy, transportation, manufacturing, and agriculture, and transforming operations across the global economy.
The lead author and PhD candidate Luis Campos indicated that they now have a method to produce sustainable hydrogen from seawater, which is widely available, using only sunlight to drive green hydrogen production.
Professor Kourosh Kalantar-Zadeh, senior researcher at the School of Chemical and Biomolecular Engineering, described the study as an impressive demonstration of how the natural chemistry of liquid metals can be harnessed to produce hydrogen. His team achieved a peak hydrogen production efficiency of 12.9 percent and is working to improve this further for commercial applications.
“For the first proof-of-concept, we consider the efficiency of this technology to be highly competitive. For instance, silicon based solar cells started with six percent in the 1950s and did not pass 10 percent till the1990s.”
The project co-lead Dr. Francois Allioux indicated that hydrogen offers a clean energy solution for a sustainable future and could play a pivotal role for Australia’s international advantage in a hydrogen economy.
At the core of this technology is gallium, a metal that melts at a relatively low temperature, which means it requires less energy to shift from solid to liquid. For years, Professor Kalantar-Zadeh’s team has been exploring the chemical and technical potential of liquid metals to develop innovative materials. They became particularly interested in gallium particles for their light-absorbing properties.
This discovery led to a technology that operates through a circular chemical process: gallium particles are suspended in freshwater or seawater and exposed to sunlight or artificial light. The gallium reacts with water to form gallium oxyhydroxide, releasing hydrogen in the process.
Professor Kalantar-Zadeh indicated that once they collect the hydrogen, the gallium oxyhydroxide can be converted back into gallium and reused for more hydrogen production – a process they refer to as circular.
Liquid gallium is an intriguing element. At room temperature, it appears as a solid metal, but when warmed to around body temperature, it melts into silvery liquid pools.
Mr. Campos explained that the surface of liquid gallium is highly chemically “non-adhesive,” meaning most substances do not stick to it under normal circumstances. However, when it is illuminated while submerged in water, the surface of liquid gallium undergoes a reaction, slowly oxidising and corroding. This process produces pure hydrogen and forms gallium oxyhydroxide on the surface.
Professor Kalantar-Zadeh indicated that gallium has never been studied before as a material for rapidly generating hydrogen in contact with water and it is a simple effect that was overlooked until now.
The research, led by the University of Sydney, was published in Nature Communications.
Hydrogen is widely regarded by scientists and industries as a promising sustainable energy source, capable of significantly reducing greenhouse gas emissions. True ‘green’ hydrogen, as the term implies, is produced using renewable energy.
Hydrogen is one of the most plentiful elements on Earth and can be extracted from numerous compounds, including water, which contains two hydrogen atoms per molecule. When hydrogen combusts, it generates energy without producing pollutants, releasing only water as a byproduct.
