University of Sydney researchers have developed a liquid metal-based method that produces clean hydrogen from seawater using nothing but sunlight. Led by Professor Kourosh Kalantar-Zadeh, the team achieved 12.9 percent efficiency with their gallium-based circular process, solving a key problem that has stalled green hydrogen production for decades.
Hydrogen has long been the great green hope. Clean-burning, abundant, and powerful. But there is a catch: producing it sustainably has been stubbornly expensive and technically difficult. Now, a team at the University of Sydney has demonstrated a way to pull hydrogen from both freshwater and seawater using liquid metal and light. It is the kind of breakthrough that makes you wonder why no one tried it sooner.
Here is what the product actually does. It solves the problem of water splitting without purified water or expensive catalysts. Current methods often require electricity, platinum, or membranes. This one simply needs water, a vat of liquid gallium, and sunlight or artificial light. According to lead author and PhD candidate Luis Campos, “We now have a way of extracting sustainable hydrogen, using seawater, which is easily accessible while relying solely on light.”
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The basic function is surprisingly straightforward. Tiny particles of gallium are suspended in water. When exposed to light, the gallium reacts with the water, oxidising to form gallium oxyhydroxide. In that reaction, hydrogen is released. The gas can then be captured and used for energy, fuel, or industrial processes. The remaining compound can be reduced back into gallium and reused. It is circular. It is clean. And it runs on light.
But there is a limitation. The current efficiency sits at 12.9 percent, which is promising for a proof-of-concept, but not yet commercially viable. The team is upfront about this. Professor Kalantar-Zadeh compares it to early solar cells: “Silicon based solar cells started with six percent in the 1950s and did not pass 10 percent till the 1990s.” His team is now working to improve the efficiency and scale the technology into a mid-scale reactor.
So why does this matter? Because green hydrogen has been trapped in a cycle of high cost and low yield. Most methods require purified water, which is expensive and energy-intensive to produce. Others rely on rare materials or generate low output. This method works with seawater, uses abundant gallium, and captures hydrogen through a light-driven reaction. It is efficient, scalable, and surprisingly simple. As project co-lead Dr. Francois Allioux noted, “Hydrogen offers a clean energy solution for a sustainable future and could play a pivotal role in Australia’s international advantage in a hydrogen economy.”
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The innovator behind the idea is Professor Kourosh Kalantar-Zadeh, a chemical engineer who has spent years studying the unusual properties of liquid metals. His team at the School of Chemical and Biomolecular Engineering observed that gallium particles absorb light in a way that triggers a chemical reaction with water. That observation, once explored, became the foundation of the entire process. According to Kalantar-Zadeh, “Gallium has not been explored before as a way to produce hydrogen at high rates when in contact with water—such a simple observation that was ignored previously.” The engineers who built the system, including Campos and Dr. Allioux, translated that insight into a working reactor.
The beauty of gallium is its strangeness. At room temperature it looks like a solid metal. Heat it slightly—to body temperature—and it becomes a liquid puddle. Its surface is chemically non-sticky, meaning most materials slide right off. But when light hits it in water, that surface begins to oxidise. Slowly. Precisely. And hydrogen bubbles up.
The research, reported by Nature Communications, offers a genuine alternative to electrolysis and photocatalysis. It avoids purified water. It avoids precious metals. It runs on sunlight. The team’s next goal is to build a mid-scale demonstration reactor and push efficiency higher. If they succeed, this quiet innovation from Sydney could become a cornerstone of the global hydrogen economy.
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