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Solid catalyst breaks the rules: Oxygen evolution steps can happen simultaneously

Oxygen evolution is considered one of the most energy-intensive steps in water electrolysis and is therefore a key factor for more efficient green hydrogen production. Modeling of the reaction mechanisms has so far been based on the assumption that the elementary steps take place sequentially and not in a concerted manner.

A team led by Prof. Dr. Kai S. Exner from the University of Duisburg-Essen has now shown that this assumption is not always correct. The results, published in Nature Communications, open up new possibilities for improving solid catalysts for energy conversion and storage applications.

There are two basic types of catalysis: homogeneous catalysts have the same physical state as the substances being converted (e.g., they all are liquid), while are in a different phase, for example a solid that reacts with liquids or gases. For a reaction to take place on the surface of a solid catalyst, the starting materials (reactants) must attach to its surface (adsorption) and then dissolve again after the reaction has taken place (desorption).

Scientists uncover ‘superfamily’ of bacterial predator proteins

Scientists have identified a new type of protein in bacteria that could change our understanding of how these organisms interact with their environments.

A new study, published in Nature Communications, focuses on a protein called PopA, found in the bacterial predator Bdellovibrio bacteriovorus. The protein forms a unique fivefold structure, unlike the usual single or three-part structures seen in similar proteins.

An international research team, led by University of Birmingham scientists, used advanced imaging techniques to reveal that PopA has a bowl-like shape that can trap parts of the bacterial membrane inside it.

An approach to realize heralded photon storage in a Rydberg superatom

Quantum technologies, systems that operate leveraging quantum mechanical effects, have the potential to outperform classical technologies in some specific tasks. Over the past decades, some researchers have also been trying to realize quantum networks, systems comprised of multiple connected quantum devices.

So far, have been the most widely used particles for carrying across different devices in quantum networks. The main reasons for this are that photons can travel at remarkable speeds, while weakly interacting with their surrounding environment, which helps to preserve the quantum states they are carrying.

To successfully employ photons in quantum networks, however, physicists and engineers need to be able to confirm that they are stored successfully without destroying them.

Cold hydrogen clouds discovered inside superheated Fermi bubbles at Milky Way’s center

Researchers have found clouds of cold gas embedded deep within larger, superheated gas clouds—or Fermi bubbles—at the Milky Way’s center. The finding challenges current models of Fermi bubble formation and reveals that the bubbles are much younger than previously estimated.

Hydrogen atom transfer method selectively transforms carboxylic acids using an inexpensive photocatalyst

Carboxylic acids are ubiquitous in bioactive organic molecules and readily available chemical building blocks. Carboxylic acids can be converted into carboxy radicals that can initiate versatile carbon–carbon and carbon–heteroatom bond formations, which are highly desirable for developing materials and pharmaceuticals. Currently, however, there are few applicable methods that use inexpensive catalysts.

To this end, researchers from WPI-ICReDD and University of Shizuoka have developed a facile hydrogen atom transfer (HAT) method that selectively transforms into carboxy radicals using xanthone, an inexpensive commercial organic ketone photocatalyst. This research was published in the Journal of the American Chemical Society.

HAT converts substrates into radical species by removing a hydrogen atom and ketones are highly accessible, inexpensive, and known for HAT photocatalysis. However, selective HAT for carboxylic acids is challenging because the O–H bond is stronger than adjacent C–H bonds. Nonetheless, using the artificial force–induced reaction (AFIR) method, a developed at ICReDD, the authors identified xanthone as a promising ketone photocatalyst for selective O–H bond HAT.

Physicists reveal how a lone spinon emerges in quantum magnetic models

Researchers from the Faculty of Physics at the University of Warsaw and the University of British Columbia have described how a so-called lone spinon—an exotic quantum excitation that is a single unpaired spin—can arise in magnetic models. The discovery deepens our understanding of the nature of magnetism and could have implications for the development of future technologies such as quantum computers and new magnetic materials. The work is published in Physical Review Letters.

Magnetism has been known to humanity since ancient times, when naturally magnetized magnetite was discovered. This finding soon found highly practical applications. The first compasses were created in the in China, and began to be used for navigation.

Today, magnets play an important role in many technologies that surround us, from computer memory and speakers to and medical diagnostics. Interestingly, alongside photography, magnets have also become a common souvenir of travel, occupying a prominent place in our homes.

Detecting Ice Structures from Space

Depending on the temperature and pressure, ice adopts one of 20 different crystalline phases. Researchers can typically tell one ice phase from the other using x rays or neutron beams, but such techniques are impractical for studying ice on distant celestial bodies. Thomas Loerting from the University of Innsbruck in Austria and his colleagues have now shown that infrared spectroscopy can discriminate between two types of high-pressure ice [1]. The results suggest that astronomical observatories in the infrared could probe ice-covered planets or moons, revealing information about their geological evolution and potential habitability.

The ice in your freezer is hexagonal ice, but at lower temperatures, higher pressures, or both, other forms can exist. Ice phases are distinguished by the ordering of oxygen atoms and hydrogen atoms. For example, ice V has oxygens arranged in ring structures, while its hydrogens have random (disordered) positions. This phase, which is stable at pressures of 500 megapascals and temperatures of 253 K, is thought to form in the interior of Jupiter’s moon Ganymede, Saturn’s moon Enceladus, and other icy moons.

In the lab, Loerting’s colleague, Christina Tonauer, created ice V, along with a related, hydrogen-ordered version called ice XIII. The team performed near-infrared spectroscopy on both samples and identified several distinguishing features, including a structure-dependent “shoulder” around 1.6 µm, a wavelength associated with stretching modes. According to the team’s calculations, the features are strong enough that astronomical instruments, such as those on the JWST observatory and the Jupiter-visiting JUICE mission, could potentially observe them on a body like Ganymede. “The detection of high-pressure ice phases at or near the surface could point to internal processes such as tectonic activity, cryovolcanism, or convective transport from deeper layers,” Loerting says.

Rethinking the Anomalous Hall Effect: A Symmetry Revolution

A new symmetry-breaking scenario provides a comprehensive description of magnetic behavior associated with the anomalous Hall effect.

In 1879 Edwin Hall discovered that a flat conductor carrying current, when placed in a magnetic field, will develop a transverse voltage caused by the deflection of charge carriers. Two years later he discovered that the same effect arises in ferromagnets even without an applied magnetic field. Dubbed the anomalous Hall effect (AHE), that phenomenon, alongside the ordinary Hall effect, not only catalyzed the rise of semiconductor physics and solid-state electronics but also laid the groundwork for a revolutionary convergence of topology and condensed-matter physics a century after Hall’s discoveries. Recent experiments, however, have uncovered behavior that cannot be explained with current theories for the AHE.