Scientists at Stanford University are in the spotlight today, as they have managed to come up with a very affordable water splitter device, using one single catalyst and being able to produce both hydrogen and oxygen gas with a minimum of electrical input. We’re looking at something that could now become the next source of renewable fuel for industries such as transportation and manufacturing, using only clean-burning hydrogen to do it.
Moving from one level of clarity to another, scientists have now taken hydrogen production to new heights. By testing different metal-oxides, well known from the area of battery development, Haotian Wang, graduate student and lead author of the study, discovered that nickel-iron oxide, in combination with electrochemical tuning, could provide them with a never before seen efficiency in the process of water-splitting.
“Our water splitter is unique, because we only use one catalyst, nickel-iron oxide, for both electrodes. This bifunctional catalyst can split water continuously for more than a week, with a steady input of just 1.5 volts of electricity. That’s an unprecedented water-splitting efficiency of 82 percent at room temperature.”
The problem before this discovery has been that conventional hydrogen production through water-splitting was bound to use both acidic and alkaline electrolytes for the hydrogen and oxygen catalysts, otherwise they would lose stability and couldn’t remain active. And with the results from a test, where they used platinum and iridium as catalysts, even if they only needed 1.56 volts to split the water, they still lost so much efficiency after 30 hours that they had to increase the voltage with almost 40 percent. Iridium and platinum are very rare and expensive metals, and the need for two different types of catalysts also created the need for a third part, a barrier that could keep the two electrolytes separated during the process.
A team of scientists at Stanford University decided to take on the challenge of finding one single catalyst that could be used, rather than the conventional use of two different catalysts, requiring different pH-levels to work properly. By peeking into the battery research, where a lithium-induced electro-chemical tuning technique was used, they believed they could solve the problem.
With this technique, lithium ions are used to break down the metal oxide catalyst chemically into smaller pieces.
Yi Cui, co-author and also Associate Professor of Materials Science and Engineering at Stanford, and of Photon Science at the SLAC National Accelerator Laboratory, explains how the process works: “Breaking down metal oxide into tiny particles increases its surface area and exposes lots of ultra-small, interconnected grain boundaries that become active sites for the water-splitting catalytic reaction. This process creates tiny particles that are strongly connected, so the catalyst has very good electrical conductivity and stability.”
By identifying the nickel-iron oxide as a world-record performing catalyst, able to catalyze both the oxygen and the hydrogen reaction in one go, and adding the electrochemical tuning, the team was very pleased with the result – a stabile and cheap process, running a production of hydrogen from water-splitting for 200 hours on a single 1.5 volt battery.
Clean-burning hydrogen fuel is one of the big hopes for future energy needs in the light of global warming, and with this discovery, the important step to make it a lot more financially viable and available for large-scale use has been taken.
The study was published June 23 in the journal Nature Commuications.
Image: Stanford University