Researchers at the University of California Santa, Santa Cruz (UCSC) have developed a new method to efficiently produce hydrogen from water at room temperature using aluminum and gallium.
The research was published in the journal Applied Nano Materials in February and is pending a US patent application.
Aluminum is an excellent candidate material for this purpose because the highly reactive metal readily reacts with oxygen molecules in water to release hydrogen gas. But the pure form of the metal is so reactive that it immediately reacts with air to form a coating of aluminum oxide on its surface, meaning it cannot react with water.
That’s where gallium comes in. Gallium is liquid at slightly above room temperature and removes the aluminum oxide coating that forms on the bare metal, allowing it to come into direct contact with and react with water. The reaction of aluminum and gallium with water to form hydrogen gas is already common scientific knowledge, but the new technology contains innovations that bring it closer to practical applications.
According to the researchers, previous such studies mostly focused on the use of aluminum-rich composites. But they found that using a gallium-rich mixture led to an unexpectedly high rate of hydrogen production.
“After this process, we could easily recover 95 percent of the gallium used without optimization. The only other product that was created was aluminum oxide [Aluminum Oxide], which can be used for many other applications,” Scott Oliver, corresponding author of the research paper, told indianexpress.com via email.
This is important because gallium is an expensive and rare mineral. Alumina has many applications, including spark plugs, wear-resistant tiles, and cutting tools.
Thanks to the new proportion of the composite, the gallium not only removed the aluminum oxide coating, but also separated the aluminum into nanoparticles, which helped speed up the reaction. The researchers found that a 3:1 ratio of gallium to aluminum in the composite is the optimal ratio for the highest hydrogen production. In addition, the composite is very easy to form. Scientists created it by mixing a small amount of aluminum into gallium by hand.
While it remains to be seen whether the technology can be scaled up to produce hydrogen in commercial quantities, the researchers are optimistic. “The technology should be able to be scaled up to an industrial level of production. We were only limited by our hydrogen volume meter and campus hydrogen limits. Scaling up will require control of the mixing of the alloy, but the reaction is spontaneous when water is added,” added Oliver.
The global push for electric vehicles has largely focused on battery electric vehicles (BEVs), which typically use lithium-ion batteries to store electricity that can be used to power the vehicle with electric motors. Alternative technology involves using “hydrogen fuel cells” to generate electricity from hydrogen and use it to power a vehicle.
Hydrogen fuel cell vehicles have some advantages over BEVs – they can be filled with hydrogen as quickly as a conventional vehicle can be filled with fossil fuels. They also reduce dependence on minerals such as lithium and cobalt, which are used to make lithium-ion batteries.
However, the use of hydrogen also has a major disadvantage. According to the US Department of Energy, most of the world’s production of hydrogen gas comes from the reforming of fossil fuels such as natural gas. And producing hydrogen using electricity from renewable sources is an energy-intensive process. New technologies like the one being developed by UCSC could remove this barrier to large-scale adoption of hydrogen fuel.