Stanford’s Low-Carbon Water Splitter Produces Hydrogen 24-7

Stanford water splitter
Stanford scientists have invented a device that produces clean-burning hydrogen from water 24 hours a day, seven days a week. Unlike conventional water splitters, the Stanford device uses a single low-cost catalyst to generate hydrogen bubbles on one electrode and oxygen bubbles on the other. CREDIT L.A. Cicero/Stanford News Service

Stanford University scientists have invented a low-cost water splitter that uses a single catalyst to produce both hydrogen and oxygen gas 24 hours a day, seven days a week.

The device, described in a study published June 23 in Nature Communications, could provide a renewable source of clean-burning hydrogen fuel for transportation and industry.

‘We have developed a low-voltage, single-catalyst water splitter that continuously generates hydrogen and oxygen for more than 200 hours, an exciting world-record performance,’ said study co-author Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at the SLAC National Accelerator Laboratory.

In an engineering first, Cui and his colleagues used lithium-ion battery technology to create one low-cost catalyst that is capable of driving the entire water-splitting reaction.

‘Our group has pioneered the idea of using lithium-ion batteries to search for catalysts,’ Cui said. ‘Our hope is that this technique will lead to the discovery of new catalysts for other reactions beyond water splitting.’

Clean hydrogen

Hydrogen has long been promoted as an emissions-free alternative to gasoline. Despite its sustainable reputation, most commercial-grade hydrogen is made from natural gas, a fossil fuel that contributes to global warming. As an alternative, scientists have been trying to develop a cheap and efficient way to extract pure hydrogen from water.

A conventional water-splitting device consists of two electrodes submerged in a water-based electrolyte. A low-voltage current applied to the electrodes drives a catalytic reaction that separates molecules of H2O, releasing bubbles of hydrogen on one electrode and oxygen on the other.

Each electrode is embedded with a different catalyst, typically platinum and iridium, two rare and costly metals. But in 2014, Stanford chemist Hongjie Dai developed a water splitter made of inexpensive nickel and iron that runs on an ordinary 1.5-volt battery.

Single catalyst

In the new study, Cui and his colleagues advanced that technology further.

‘Our water splitter is unique, because we only use one catalyst, nickel-iron oxide, for both electrodes,’ said graduate student Haotian Wang, lead author of the study. ‘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.’

In conventional water splitters, the hydrogen and oxygen catalysts often require different electrolytes with different pH — one acidic, one alkaline — to remain stable and active. ‘For practical water splitting, an expensive barrier is needed to separate the two electrolytes, adding to the cost of the device,’ Wang said. ‘But our single-catalyst water splitter operates efficiently in one electrolyte with a uniform pH.’

Wang and his colleagues discovered that nickel-iron oxide, which is cheap and easy to produce, is actually more stable than some commercial catalysts made of precious metals.

‘We built a conventional water splitter with two benchmark catalysts, one platinum and one iridium,’ Wang said. ‘At first the device only needed 1.56 volts of electricity to split water, but within 30 hours we had to increase the voltage nearly 40 percent. That’s a significant loss of efficiency.’

Marriage of batteries and catalysis

To find catalytic material suitable for both electrodes, the Stanford team borrowed a technique used in battery research called lithium-induced electrochemical tuning. The idea is to use lithium ions to chemically break the metal oxide catalyst into smaller and smaller pieces.

‘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,’ Cui said. ‘This process creates tiny particles that are strongly connected, so the catalyst has very good electrical conductivity and stability.’

Wang used electrochemical tuning — putting lithium in, taking lithium out — to test the catalytic potential of several metal oxides.

‘Haotian eventually discovered that nickel-iron oxide is a world-record performing material that can catalyze both the hydrogen and the oxygen reaction,’ Cui said. ‘No other catalyst can do this with such great performance.’

Using one catalyst made of nickel and iron has significant implications in terms of cost, he added.

‘Not only are the materials cheaper, but having a single catalyst also reduces two sets of capital investment to one,’ Cui said. ‘We believe that electrochemical tuning can be used to find new catalysts for other chemical fuels beyond hydrogen. The technique has been used in battery research for many years, but it’s a new approach for catalysis. The marriage of these two fields is very powerful. ‘

Other Stanford co-authors of the study are postdoctoral scholar Hyun-Wook Lee, visiting student Zhiyi Lu, and graduate students Yong Deng, Po-Chun Hsu, Yayuan Liu and Dingchang Lin.

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This post was prepared by Solar Thermal Magazine staff.


  • Lucino H.Butanas says:

    In what pressure hydrogen fuel be come a burning fuel inside the combustion chamber of the engine. Thnks

  • rich k says:

    No matter where you go for info on renewable the one Constant is the writer climing as fact that fossil fuel use creates AGW on a scale as to be harmful to the worlds ecosystem. Wrong on all counts Staff. The worlds Volcanoes produce more co2 to the atmosphere than all of the fossil fuels used for the last 100 years.Idiots.

  • Anna Keppa says:

    Gosh! Another step forward toward the Hydrogen Economy!

    Except….I’m wondering what the effects will be of adding thousands of tons of H20 vapor exhausted from Hydrogen-powered vehicles, ESPECIALLY in humid urban areas like NOLA and Washington.

    80% relative humidity on 90 degree days, anyone?

    But wait: the Green Weenies will blame climate change, so…no problemo!

    • Gaia says:

      Water H20 is no problem whatsoever. I don’t think it will raise the humidity in any noticeable way and if it did it would likely contribute to a cooling effect as when it evaporates it lowers the temperature.

  • Sinnamon Buns says:

    A 1.5 volt hydrogen splitter might be an innovation but surely what one must ask after knowing this one fact is how many amperes are required to produce one litre of H2 in an hour. This question was not asked for some reason. Of course, one also wants to know what this will cost, though I suspect that that figure is, so far, unknown.

    • richard40 says:

      The key question for me would be how much electricity it takes to generate the hydrogen/oxygen, vs how much electricity those 2 would generate if used again in a hydrogen/oxygen fuel cell. If you only lost 20% on that transaction, that is pretty good, if you lose 60% of the energy, that is bad.

  • JM Irvine says:

    What am I not getting here? It is my understanding that there is a severe water shortage, aquifers are shrinking and the world’s supply of water is the coming crisis. Am I wrong?

    Hydrogen as a fuel source versus drinking water. Hmmm, again, what am I missing?

    I will believe that climate change is a serious problem when serious, not frivolous and punitive, action is taken by the elite powers that be. I’ll believe it when huge swathes of land undergo tree replanting for O2 production, land cooling, carbon absorption, and increased precipitation. Then, and when nuclear power becomes the primary engine of our economy.

    Please, do not devote science to tipping the scales on the world’s drinking water supplies.

    • richard40 says:

      The worldwide water shortage is something of a myth. What you really have is a shortage of fresh water, in some places. But many other places have plenty of fresh water, and the world has more salt water in the oceans than we could ever use. I understand that this system can work with salt water as well, which makes it practical pretty much anyplace.

    • Peter Brown says:

      If you used seawater to produce it , and condensed the water vapour produced to irrigate , seems it would be win win and might even lower oceans levels if it was used enough even if only in a small way

  • Pat Dooley says:

    You had to sneak in \natural gas, a fossil fuel that contributes to global warming\,

    Where did the Carbon in fossil fuels come from? Wasn’t it was all in the atmosphere aeons ago? And why didn’t the Earth burn up then when CO2 concentrations were 20 times higher than today?

    Global temperatures were higher during the Holocene maximum and Roman Times before SUVs roamed the Earth. Why the panic when temperatures have been stable for fifteen years, ice is increasing in the Antarctica, and the sun is going quiet?

    The ICC computer models, that assume CO2 causes global warming, have been useless in predicting anything.

  • Gaia says:

    This video explain why the earth did not urn up aeons ago when the CO2 levels where de facto higher than today:
    It’s much more complex than you think. It has not only to do with CO2 levels.

    The latest time the CO2 level was higher than today was 3-25 million years ago:

    It was not as you state during the Holocene or Roman times though, as this research shows:
    Not during 800,000 years have the CO2 levels de facto been higher or even close to as high than today as ice core samples shows.

    The temperatures have NOT been stable the last 15 years (which is a too short period to draw conclusions from as this data shows:

    My advice to you is that since you do not yet understand those things it’s better you use your time to study them. At real scientific organisations that is. Not pseudo science blogs that is at best cherry picking data and presenting it out of context. After all, more than 97% of climate scientists agree that climate change is real and cause by humans.
    Your children and grandchildren will thank you for it.

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