A New Aerogel Could Produce 70 Times More Hydrogen Than Rival Methods

Even at industrial scales, potentially.
Brad Bergan
The aerogel, and the same plus a rose and Bunsen burner.Markus Niederberger / ETH Zurich

The future of energy is nearly here.

And a team of scientists has created a new aerogel that increased the efficiency of converting light into hydrogen energy, producing "up to 70 times more hydrogen" than rival methods, according to a recent study published in the journal Applied Materials & Interfaces.

And, given enough time, this could become the beginning of a new means of producing hydrogen fuel at industrial scales. That means hydrogen combustion vehicles, novel aircraft propulsion, and, just maybe, future power grids.

'Doped' nanoparticles can absorb more sunlight

In case you missed it, aerogels are so impressive that they've set Guinness World Records more than a dozen times, including the honorary position of becoming one of the world's lightest solids. Aerogels based on nanoparticles can be used as a photocatalyst, which enables or accelerates chemical reactions (when combined with sunlight) to produce extremely useful products in the modern world, including hydrogen. The optimal material for photocatalysts is titanium dioxide (TiO2), which is also a semiconductor. But it has a serious flaw: it only absorbs the UV spectrum of sunlight, which is only 5% of the total shine of the sun. To prove efficient and useful in energy industries, photocatalysts need to leverage a broader spectrum of wavelengths.

This is the goal of Professor Markus Niederberger and his team at ETH Zurich's lab for multifunctional materials. Niederberger's doctoral student, Junggou Kwon, has sought new and alternative ways to optimize the efficiency of aerogels forged from TiO2 nanoparticles. She discovered that by "doping" the TiO2 nanoparticle with nitrogen to ensure that discrete oxygen atoms in the material are replaced by nitrogen atoms, the aerogel is made capable of absorbing even more visible portions of the sun's spectrum. This process also allows the aerogel's porous structure to remain intact.

Palladium-infused aerogels can generate 70 times more hydrogen

At first, Kwon produced the aerogel using TiO2 nanoparticles in conjunction with only small amounts of the noble metal palladium. Palladium is useful because it plays a critical role in the photocatalytic production of hydrogen. But Kwon then lowered the aerogel into a reactor, where it was infused with ammonia gas, forcing nitrogen atoms to become embedded in TiO2 nanoparticles' crystal structure, according to a blog post on the website of the Swiss Federal Institute of Technology, in Zürich. But to verify that an aerogel modified like this could actually raise the efficiency of the desired chemical reaction (specifically, converting methanol and water into hydrogen), Kwon built a specialized reactor. Then she inserted water vapor and methanol into the aerogel, and then irradiated the mixture with a pair of LED lights.

The result was a gaseous substance that diffused through the aerogel's pores, where it was converted into the desired hydrogen on the TiO2's surface and palladium nanoparticles. While Kwon concluded the experiment after five days, the reaction remained stable throughout the test. "The process would probably have been stable longer," said Niederberger in the ETH Zurich blog post. "Especially with regard to industrial applications, it's important for it to be stable for as long as possible." Most crucially, adding the noble metal palladium substantially increased the conservation efficiency of the reaction. In other words, combining aerogels with palladium can generate up to 70 times more hydrogen than other alternative means. This could be the beginning of a new more advanced method of producing hydrogen at industrial scales, not only as a way to free cars and air travel from fossil fuels, but also for larger power grids.

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