Adding magnets to lower the cost of hydrogen production

Researchers at IIT-Bombay have discovered a new way of producing hydrogen by using magnetised catalysts during electrolysis. This lowers energy consumption, in the process.

High school physics tells us that the simplest way to produce hydrogen is by splitting water into its constituent elements, hydrogen and oxygen. But this method calls for energy (electricity), because the chemical bonds between hydrogen and oxygen are very strong. Besides, if you already have electricity, why not use it directly rather than for producing hydrogen? The splitting of water — electrolysis — essentially means you are using hydrogen only as an energy store, rather than an energy source.

However, while some scientists are trying to figure out alternative ways of producing the gas — such as reacting metals with water and carbon dioxide, using biomass or microbes — others are persisting with electrolysis, trying to improve the process by lowering energy consumption.

It is in such a quest that three professors of the Department of Chemistry, IIT-Bombay — Jayeeta Saha, Ranadeb Ball and Chandramouli Subramanian — have found success. Their work has been published in the journal ACS Sustainable Chemistry & Engineering . The experts have shown that their catalyst could speed up hydrogen production with lower energy consumption.

In electrolysis, two electrodes are inserted across water and current is passed through the electrodes. It has been known that metals like platinum, rhodium, and iridium speed up electrolysis — but these are expensive and, hence, not preferred.

The IIT-Bombay researchers made an electrode of carbon nano florets, where you have nano carbon structures arranged like a marigold flower, and added cobalt oxide to it. Then they nourished the electric field with a magnetic field, by placing two magnets outside the experimental beaker in which the electrodes were kept. The magnets were less than 300 milli tesla, same as common fridge magnets, Subramanian told Quantum .

The result: 19 per cent less energy consumption and three times the hydrogen produced without a magnetic field.

For sure, this is not the first time anyone is experimenting with the application of a magnetic field in electrolysis to enhance hydrogen production. “This field is being re-visited by many researchers in the last couple of years, Subramanian said. The uniqueness of this research is that you can remove the magnets after some time, and the system will work just as well. This means that magnets do not have to be incorporated into the architecture of the electrolyser. Once you magnetise the substrate (the electrode), it remains magnetised for some time even after the magnets are removed — because cobalt is itself a good magnet material and retains the magnetism even if the magnetic field is removed. “The catalyst we have designed can sustain the magnetisation for prolonged periods, the key being the development of a synergistic carbon-metal oxide interface,” says Saha.

If you are using electromagnets, which need electricity, you can switch off the electricity and the system will continue to function. A one-time exposure of the magnetic field is enough to achieve high-speed hydrogen production for over 45 minutes. This has a clear advantage — it is easy to integrate accessible house-magnets into existing designs at a low cost. “We can directly adopt the modified setup in existing electrolysers without any change in design or mode of operation of the electrolysers,” says Ball, another author of the study.

Adding more magnets for stronger magnetic field does not result in more hydrogen production. At around 250 milli tesla, it gets saturated, Subramanian said.

So, the essence of the system is that by using magnets you can reduce the number of cells in the stack. A cell that can produce, say, 1 cubic metres of hydrogen an hour without magnets, can produce three times as much with a magnetic field.

And now, the researchers are “working very closely with an industrial partner” to commercialise the process. “We want to see an indigenously built, magnet-based electrolysis system which can deliver hydrogen cost-effectively,” Subramanian said.

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