hydrogen storage materials

Inside the steel of a future fusion reactor, tiny helium bubbles form, and on their walls a chemical drama unfolds. Chromium and tantalum atoms, like sentinels, take positions at the cavity boundary and change the rules of the game for hydrogen.

Imagine a book with latches on its pages: you can only flip a page if you know how to click its edge. That is roughly how the mechanical metamaterial we are about to discuss works. Each cell is a small mass inside a larger one, connected by an elastic beam. The beam can sit in two stable positions, like a switch.

Every Martian night, salt crystals on the planet's surface soak up moisture from the thin air, much like a sponge draws water from a damp cloth. By morning, a microscopic brine accumulates inside them, and during the day, as temperatures rise, that brine finds itself trapped in tiny cavities.

Hot water after a shower, warm air from ventilation, the heated walls of an engine — all this is heat below 100°C. Usually, it dissipates without doing any useful work. Now it can be captured and turned into electricity. Inside the new device is a wire made of a nickel-titanium alloy. This material remembers its shape: when heated, it contracts; when cooled, it returns to its original shape.

Dark matter — the invisible architect of the universe, holding galaxies from flying apart. Thanks to the pioneering work of Fritz Zwicky and Vera Rubin we know: ordinary matter in the cosmos is just a negligible impurity. But what lies behind this dark matter?

A sub-Neptune is a planet that falls between Earth and Neptune in size. These worlds are abundant in our galaxy, but their internal structure has been hotly debated. New research shows that in their youth, these planets behave like a sponge soaked with water.

The Martian surface is a place where anything alive quickly dies. Cosmic rays and ubiquitous oxidizers sterilize the top layer of soil. But dig a little deeper, and the picture changes. There, beyond the reach of ultraviolet light, a zone suitable for life may lurk. This zone runs on a strange fuel — radiation.

Throw a ball almost parallel to a wall — it will slide along it before bouncing off. The same happens with a light beam: when reflected at a shallow angle, it shifts by microns. This Goos–Hänchen shift was long considered a mere amusing paradox.

Quantum batteries harness quantum effects to circumvent the limitations of ordinary devices imposed by entropy — a measure of disorder and energy losses. Imagine a bucket under a powerful jet: filling is lightning-fast. But the bucket has holes: the environment constantly drains the energy.

A gold speck the size of a hundred atoms catches a beam of light, and heats up. In everyday life, that's no big deal, but in the world of nanotechnology, this tiny heat can ruin a biosensor or fry a microchip. You can't just put a fan on it: at these scales, heat gets trapped like in a thick winter coat.

The Red Planet is surrounded by the rubble of failed worlds — rocky boulders stuffed with metal. Shipping a kilogram of steel from Earth to Mars costs as much as several cars. It's far cheaper to pick up space junk right in orbit.

Previously it was thought that hydrogen barely mixes with liquid iron at low pressure, so it wasn't expected in the Moon's core. New experiments have flipped that view.

Hydrogen is an ideal fuel: when used, it only produces water, not carbon dioxide. The trouble is that hydrogen is the lightest gas, its molecules leak out of any container. Right now, cars store hydrogen in heavy tanks under extreme pressure, canceling out weight benefits. Researchers bypassed the problem without high pressure.

Conventional solar panels convert light into electricity, but here light splits water into hydrogen and oxygen. Hydrogen is a clean fuel, but the process is slow. To speed it up, helper substances that donate electrons are added. Often this is alcohol, but it's a shame to waste it.

When servers in a data center run at full tilt, they get as hot as a forgotten iron. That heat goes to waste, and cooling them eats up even more energy. Engineers in Germany have proposed putting that heat to work: let it drive liquid through thin tubes all by itself, with no motors or pumps. Their device looks like a flat box with an asymmetric bottom.

Hydrogen is the lightest gas, but it has a knack for sneaking into metals. If you pump hydrogen into a steel cylinder at high pressure, some atoms will squeeze between the metal atoms. The metal can become as brittle as a stale cracker. But you can also turn this property on its head — store hydrogen inside a metal sponge.

A membrane for water electrolysis is like a sponge soaked with water. Inside it, hydroxide ions, particles that carry electric charge, must move freely. But exactly how they move has long been a mystery: tracking each ion in an experiment is too difficult.

Hydrogen is a champion in energy per kilogram, but storing it is a hassle. As a gas, it takes up a huge volume, and if you compress it or cool it to a liquid, you need heavy tanks and lots of energy. There's a third way: some solid materials absorb hydrogen like a sponge soaks up water and hold it within. Heat it up, hydrogen comes out; cool it down, it gets absorbed back.

Today's Martian surface is a cold, nearly airless home. Many dream of a full renovation: warming the planet, filling it with air from carbon dioxide and nitrogen.

Iron powder heated to 650–800 degrees absorbs hydrogen like a dry sponge soaks up water. But after a few cycles, the particles fuse into a dense lump, and the sponge stops working. Adding tungsten changes the picture: with each heating, the powder foams itself, staying loose and porous.

Hydrogen is a clean fuel: when it burns, it produces only water. But to extract it from water, you need to break the strong bond between hydrogen and oxygen. This is usually done with platinum, an expensive metal.

Modern batteries with liquid electrolytes can leak or catch fire. Polymer electrolytes (solid, plastic-like materials) solve that problem, but ions move through them more slowly, so the battery loses power. Researchers set up a virtual assembly line: a computer program generated new polymer structures the way a chef experiments with new dough recipes.

Inside a fuel cell, protons must race through a solid material like commuters through turnstiles at rush hour. If the turnstiles are sparse and narrow, the current is weak. In the past, to find a material with good proton conductivity, chemists had to screen compounds almost blindly, one by one.

An ordinary wire heats up when current flows through it. A superconductor doesn't. But almost all known superconductors require either very low temperatures or enormous pressures, like those deep inside planets. Scientists have long searched for a material that avoids these extremes.

An old T-shirt was dissolved in alkali to produce a gel, and it became the heart of an energy storage device. The second component was made from chitosan, a substance derived from shrimp shells. No metals: just recycled cotton and seafood. The gel was soaked in ammonium salt, and its conductivity nearly doubled: from 17.1 to 37.8 millisiemens per centimeter.

In a jar of oily liquid float millions of tiny magnetic grains: each about the size of a bacterium. Switch on a magnet, and the grains, like obedient little soldiers, line up into long threads. But why do they form threads rather than clumps? It turns out it's not just about magnetism.

Dark matter is invisible, but you can catch it on the rebound. Hydrogen embedded in a carbon film acts like a billiard ball: when a dark matter particle hits it, the proton flies out. That ejection is the signal you're looking for.

A printer that prints not with ink but with metal and ceramic is now a reality. Scientists took an ordinary drop of water containing dissolved metal salts and made it deposit copper, zinc oxide, or nickel hydroxide onto a surface — all with precision down to millionths of a meter. The secret lies in electricity.

To find out if a Mars rock holds water without smashing it, scientists used neutron and X-ray scanning — similar to medical imaging. Neutrons pick up hydrogen, the foundation of water, allowing them to map moisture inside the sample.

At the centers of many galaxies lurk supermassive black holes, surrounded by disks of gas, cosmic dust, and stars. Their collisions can spawn gravitational waves — ripples in spacetime.

The usual way to freeze a living cell is like trying to put a spacesuit on it: you first need to get a protective substance inside, but while it's crossing the membrane, the cell can burst from salt imbalances or get poisoned by the chemicals.

A fusion reactor resembles a giant boiler where hydrogen is 'cooked' into helium. The plasma inside is heated to 150 million degrees — ten times hotter than the Sun's core. But like any boiler, scale forms: harmful impurities that settle on the walls and quench the plasma.