New Semiconductor Using Sunlight Unlocks Green Hydrogen Potential

Automobiles with thousands of kilometers of range, sustainable aviation and renewable power storage are some of the possibilities opened up by green hydrogen production. It is also the second pillar of the renewable energy revolution. Where wind and solar energy provide electricity, green hydrogen can also replace fossil fuels in industrial processes that require heating power. A major challenge for this technology is for new catalysts developed by the University of Michigan in the United States to achieve commercial viability.

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What are the main technologies to produce green hydrogen?

Most of the hydrogen on earth is found in water, so all efforts to obtain green hydrogen aim to break the atomic bonds and separate it from oxygen. Three types of reactions are currently used to accomplish this.

1. electrochemistry (electrolysis)They are based on the transmission of electrical current through electrodes (anode and cathode) that are immersed in water containing electrolytes such as salts and acids that increase electrical conductivity. In this case, electricity from renewable sources is used to produce green hydrogen.
2. Photocatalyst/PhotoelectrochemistryThese harness sunlight and, when in contact with a catalyst or semiconductor catalyzed by photoelectrochemical materials, convert photons into free electrons to release hydrogen from water. This process is similar to photosynthesis in which plants obtain hydrogen atoms from water from sunlight.
3. thermochemistryIt is based on applying high temperatures that can break down water molecules, converting thermal energy into chemical energy. Either a single step – pyrolysis – at temperatures above 2,000 ºC or a thermochemical cycle with lower temperature steps.

New self-healing green hydrogen catalyst

So far, industrial-scale green hydrogen production has focused on electrochemical techniques, but research on photocatalytic and photoelectrochemical techniques has yielded promising results. The main advantage is the direct use of sunlight to generate reactions, rather than converting sunlight into electricity to perform electrolysis. This may ultimately lead to higher conversion efficiencies. A major obstacle to this technology has been that the catalysts used either degrade rapidly or are very unstable. A new self-repairing green hydrogen catalyst developed by the University of Michigan is therefore a very promising technology.

The device, created by a team of US university scientists, window size lens It concentrates sunlight onto a transparent panel containing water and a new catalyst. The latter is based on indium gallium nitride nanostructures grown on silicon surfaces. Thanks to the insulating layer on the panel, temperatures of up to 75°C are reached, stimulating the photocatalytic reaction. As a result, the extraction efficiency of hydrogen from water is 9%, which is almost 10 times lower. Many times more efficient than similar technologies.

The semiconductors used have several advantages. First, it is extremely durable. Specifically, it can withstand light equivalent to 160 suns without deterioration and exhibits self-healing ability.Second, it Utilizes the entire solar spectrum: higher wavelengths to generate the reaction and infrared radiation to enhance it. Both sides have the potential to produce green hydrogen at a much lower cost.

Accelerating Green Hydrogen Production with Ultrasonics

Regardless of these advances, the production of green hydrogen using electrochemical processes has also improved significantly. The latest of these, pioneered by the University of Melbourne, Australia, involves ultrasound. Increases the amount of hydrogen produced by conventional electrolysis technology up to fourteenThis technology not only promotes hydrogen production, but also prevents oxygen and hydrogen bubbles from building up on the electrodes.

On the other hand, the efficiency of the new technology makes it possible to dispense with the usual acidic electrolytes. Likewise, the absence of acid allows electrodes to be used without expensive anti-corrosion materials such as platinum or iridium. All of this will make green hydrogen production processes cheaper and closer to commercial viability.

Overcoming the challenges of producing green hydrogen on an industrial scale will open up endless applications.For example, as pointed out in this article, It may become a great ally of sustainable aviation. And who knows if it will play an important role in urban mobility, as this bike powered by a hydrogen fuel cell shows.

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