New prototype device that generates hydrogen from untreated seawater: ScienceAlert

Scientists have found a clever way to generate hydrogen directly from salty seawater. This could be another step towards a clean energy future, if renewables power the process.

The new device makes some chemical tweaks to existing technologies, making it possible to extract hydrogen from untreated and impure seawater — potentially alleviating concerns about using up precious water supplies.

“We split natural seawater into oxygen and hydrogen…to produce green hydrogen by electrolysis, using a non-precious and cheap catalyst in a commercial electrolyzer,” Explain Chemical engineer Shizhang Qiao of the University of Adelaide in Australia.

Traditionally, hydrogen fuel has been made using natural gas, but it can also be made through electrolysis.

Electrolysis is a water splitting reaction that uses electricity to elbow hydrogen atoms out of water molecules, and the electrolyzer is a device where this happens.

Currently, this process can be accomplished using electricity from fossil fuels or from renewable energy sources, but both systems require fresh water. Finding a way to achieve electrolysis with seawater could make the future of green hydrogen fuel production more sustainable.

Researchers have been trying to develop an alternative to the commercial electrolyzer, which only works with pure fresh water, fearing a water shortage.

Accessible fresh water makes up only 1 percent of all water on the planet, but there is an almost unlimited supply of seawater that can be used.

While concerns about water scarcity are valid, recent estimates suggest that the amount of water needed to sustain future hydrogen use is much less than Trillions of liters of water were used to extract and burn fossil fuels today.

However, scientists are still aware of the environmental effects. For decades, they’ve been trying to develop devices for producing hydrogen from seawater but they’ve kept running aground Several barriers.

When exploded in an electrolyzer, unwanted chlorine ions in seawater corrode the catalysts intended to drive the water splitting reaction that produces hydrogen. Massive insoluble precipitates also form, blocking reaction sites and impeding large-scale production.

The new system developed by Qiao and colleagues avoids both of these problems.

As described in their new paper, the researchers layered a Lewis acid solid onto a series of common cobalt oxide catalysts to split water molecules. In a series of tests, the modified catalysts resisted chlorine attack and prevented any precipitates from forming.

“This is a general strategy that can be applied to different catalysts without the need for specially designed catalysts and electrolyte design,” I write The researchers in their published paper.

Although this sounds promising, the decades-old effort to develop a seawater electrolyzer should serve as a reminder of the challenges ahead in commercializing this or any other technology.

“Direct electrolysis of seawater without the purification process and chemical additions is very attractive and has been investigated for nearly 40 years, but major challenges remain for this technology in both catalyst engineering and device design,” the researchers said. Note.

Recent progress is encouraging, however, with this new device one of several promising attempts To generate hydrogen from sea water.

For example, scientists from China and recently Australia Develop a prototype of the device Designed to float on the surface of the ocean and separate hydrogen from seawater using solar energy. Another prototype in the works that takes a very different approach, Harvesting water from moist air before hydrogen extraction.

Of course, prototyping is a far cry from industrial scale methods, so it’s a good idea to have a healthy mix of potential systems in the pipeline to see which one delivers.

Qiao and colleagues are extending their system with a larger electrolyzer. But many factors can make or break a potential technology.

Commercialization of a process boils down to material cost, energy input and efficiency at scale – small gains can make a huge difference in the amount of hydrogen produced.

Cobalt, the material used in metal oxide catalysts, is, too Not without its problems. Like any precious metal used in batteries or solar panels, it must be mined sustainably and Recycled wherever possible.

After testing the robustness of their synthesis, Qiao and colleagues believe their modified catalysts can go the distance. Their system can deliver outputs similar to a commercial electrolyzer under the same low temperatures and operating conditions.

But with other researchers He takes great strides To steadily improve the efficiency of conventional electrolyzers, it’s really anyone’s game.

Research published in nature energy.

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