Chemistry news and discussions

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Using ice to boil water: Researcher makes heat transfer discovery that expands on 18th century principle
https://phys.org/news/2022-01-ice-disco ... ciple.html
by Virginia Tech
Associate Professor Jonathan Boreyko and graduate fellow Mojtaba Edalatpour have made a discovery about the properties of water that could provide an exciting addendum to a phenomenon established over two centuries ago. The discovery also holds interesting possibilities for cooling devices and processes in industrial applications using only the basic properties of water. Their work was published on Jan. 21 in the journal Physical Review Fluids.

Water can exist in three phases: a frozen solid, a liquid, and a gas. When heat is applied to a frozen solid, it becomes a liquid. When applied to the liquid, it becomes vapor. This elementary principle is familiar to anyone who has observed a glass of iced tea on a hot day, or boiled a pot of water to make spaghetti.

When the heat source is hot enough, the water's behavior changes dramatically. According to Boreyko, a water droplet deposited onto an aluminum plate heated to 150 degrees Celsius (302 degrees Fahrenheit) or above will no longer boil. Instead, the vapor that forms when the droplet approaches the surface will become trapped beneath the droplet, creating a cushion that prevents the liquid from making direct contact with the surface. The trapped vapor causes the liquid to levitate, sliding around the heated surface like an air hockey puck. This phenomenon is known as the Leidenfrost effect, named for the German doctor and theologian who first described it in a 1751 publication.
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A new way to shape a material's atomic structure with ultrafast laser light
https://phys.org/news/2022-02-material- ... laser.html
by Glennda Chui, SLAC National Accelerator Laboratory
Thermoelectric materials convert heat to electricity and vice versa, and their atomic structures are closely related to how well they perform.

Now researchers have discovered how to change the atomic structure of a highly efficient thermoelectric material, tin selenide, with intense pulses of laser light. This result opens a new way to improve thermoelectrics and a host of other materials by controlling their structure, creating materials with dramatic new properties that may not exist in nature.

"For this class of materials that's extremely important, because their functional properties are associated with their structure," said Yijing Huang, a Stanford University graduate student who played an important role in the experiments at the Department of Energy's SLAC National Accelerator Laboratory. "By changing the nature of the light you put in, you can tailor the nature of the material you create."

The experiments took place at SLAC's X-ray free-electron laser, the Linac Coherent Light Source (LCLS). The results were reported today in Physical Review X and will be highlighted in a special collection devoted to ultrafast science.

Heat versus light

Because thermoelectrics convert waste heat to electricity, they're considered a form of green energy. Thermoelectric generators provided electricity for the Apollo moon landing project, and researchers have been pursuing ways to use them to convert human body heat into electricity for charging gadgets, among other things. Run in reverse, they create a heat gradient that can be used to chill wine in refrigerators with no moving parts.
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A new, inexpensive catalyst speeds the production of oxygen from water

by David L. Chandler, Massachusetts Institute of Technology
https://phys.org/news/2022-02-inexpensi ... xygen.html
An electrochemical reaction that splits apart water molecules to produce oxygen is at the heart of multiple approaches aiming to produce alternative fuels for transportation. But this reaction has to be facilitated by a catalyst material, and today's versions require the use of rare and expensive elements such as iridium, limiting the potential of such fuel production.

Now, researchers at MIT and elsewhere have developed an entirely new type of catalyst material, called a metal hydroxide-organic framework (MHOF), which is made of inexpensive and abundant components. The family of materials allows engineers to precisely tune the catalyst's structure and composition to the needs of a particular chemical process, and it can then match or exceed the performance of conventional, more expensive catalysts.

The findings are described today in the journal Nature Materials, in a paper by MIT postdoc Shuai Yuan, graduate student Jiayu Peng, Professor Yang Shao-Horn, Professor Yuriy Román-Leshkov, and nine others.
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Researchers design a flexible system that sidesteps copper-protein binding
https://phys.org/news/2022-03-flexible- ... otein.html
by Michelle Franklin, University of California - San Diego
It may seem counterintuitive to many, but metal ions play a critical role in life, carrying out some of the most important biological processes. Think of hemoglobin—a metalloprotein responsible for carrying oxygen to the body's organs via red blood cells. Metalloproteins are proteins bound by at least one metal ion. In the case of hemoglobin, that metal is iron.

For metalloproteins to work properly, they must be paired with the correct metal ion—hemoglobin can only function with iron Yet, protein-metal binding is normally governed by a strict order, called the Irving-Williams Series, which dictates that copper ions should bind to proteins over other metals.

In other words, if a cell contained equal amounts of different metal ions, most cellular proteins and other components would bind to copper, clogging up cellular machinery in the process. This is why organisms spend considerable energy keeping very strict controls over how much free copper is present in cells.

Now researchers in the University of California San Diego's Division of Physical Sciences have reported a new protein-design strategy to sidestep the Irving-Williams Series. The findings were published earlier this week in the journal Nature.
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Research chemists find a quick way to synthesize novel neuroactive compounds found in rainforest tree
https://phys.org/news/2022-03-chemists- ... orest.html
by The Scripps Research Institute
A potential cornucopia of neuroactive compounds, which might yield clues to the design of future psychiatric and neurological drugs, has become more accessible to synthetic chemists, thanks to new work from Scripps Research.

The discovery, reported March 17, 2022, in Science, concerns compounds contained in the rainforest tree Galbulimima belgraveana and its close cousin Galbulimima baccata, which are native to Papua New Guinea, tropical northern Australia, and Malaysia.

Potions made from the bark of these trees have long been known to have hallucinogenic and other neuroactive effects, but the precise compounds involved, and their biological targets, have largely been a mystery. The Scripps Research chemists found what is essentially the first streamlined, practical method for synthesizing many of these compounds.
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New method purifies hydrogen from heavy carbon monoxide mixtures
https://techxplore.com/news/2022-03-met ... arbon.html
by Mariah Chuprinski, Pennsylvania State University
Refining metals, manufacturing fertilizers and powering fuel cells for heavy vehicles are all processes that require purified hydrogen. But purifying, or separating, that hydrogen from a mix of other gases can be difficult, with several steps. A research team led by Chris Arges, Penn State associate professor of chemical engineering, demonstrated that the process can be simplified using a pump outfitted with newly developed membrane materials.

The researchers used an electrochemical hydrogen pump to both separate and compress hydrogen with an 85% recovery rate from fuel gas mixtures known as syngas and 98.8% recovery rate from conventional water gas shift reactor exit stream—the highest value recorded. The team detailed their approach in ACS Energy Letters.

Traditional methods for hydrogen separations employ a water gas shift reactor, which involves an extra step, according to Arges. The water gas shift reactor first converts carbon monoxide into carbon dioxide, which is then sent through an absorption process to separate the hydrogen from it. Then, the purified hydrogen is pressurized using a compressor for immediate use or for storage.

The key, Arges said, is to use high-temperature, proton-selective polymer electrolyte membranes, or PEMs, which can separate hydrogen from carbon dioxide and carbon monoxide and other gas molecules quickly and cost-effectively. The electrochemical pump, equipped with the PEM and other new materials Arges developed, is more efficient than conventional methods because it simultaneously separates and compresses hydrogen from gas mixtures. It also can operate at temperatures of 200 to 250 degrees Celsius—20 to 70 degrees higher than other high-temperature-PEM-type electrochemical pumps—which improves its ability to separate hydrogen from the unwanted gasses.
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Using quantum vibration properties between molecules to speed up reactions between compounds
https://phys.org/news/2022-04-quantum-v ... tions.html
by Bob Yirka , Phys.org
A pair of researchers, one with the Southern University of Science and Technology, the other the Institute of Atomic and Molecular Sciences, has developed a means for using quantum vibration properties between molecules to speed up reactions between compounds. In their paper published in the journal Nature Chemistry, Huilin Pan and Kopin Liu describe how they used vibrations in certain types of methane molecules to speed up a reaction during mixing with chlorine using "quantum phase control."

Prior research has shown that vibrations in molecules can control how they react when mixed with one another. In this new effort, the researchers found a way to extend this principle by using some of the properties of vibrations at the quantum level—specifically, Fermi-coupled vibrations. Their goal was to learn more about how a wave function's phase would affect the reactivity between molecules when Fermi-coupled vibrations were involved. They are described as the resonance that occurs when there is a shift of intensities and energies during the absorption of bands in a Raman spectrum. They arise due to wavefunction mixing.
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Scientists synthesize novel nitride and stabilize its hexazine rings at high pressure
https://phys.org/news/2022-04-scientist ... -high.html
by Chinese Academy of Sciences

In a recent study published in Nature Chemistry, scientists reported the synthesis of a novel nitride with metallic luster and hexazine rings—the result of a six-year effort in high-pressure science.

This is the first time that a planar N62-, a dianionic hexazine nitride, has been obtained in a laboratory experiment. Furthermore, the structure remained relatively stable at pressures down to 20 GPa.

Nitrogen-rich compounds have attracted wide attention because of their great potential as high-energy density materials (HEDMs) that can store and release huge amounts of energy. However, very few nitrogen compounds have been synthesized so far in comparison with the number predicted theoretically through calculation and modeling.

"Low-order N-N bonds are hard to keep stable at low pressure," said Dr. Wang Yu, lead author of the study and a researcher at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences. According to Wang, that is why synthesizing nitrogen compounds in the laboratory is so difficult.

In previous studies, Wang and her colleagues learned that molecular diatomic nitrogen can be converted into an atomic solid with a single-bond crystalline cubic gauche (cg-N) structure in a diamond anvil at extreme pressures up to 110 GPa and 2,500 K. The result inspired the synthesis of polynitride materials at high pressure and high temperature, including the results in their experiments.
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Supercomputing and neutrons crack code to uranium compound's signature vibes
https://phys.org/news/2022-05-supercomp ... pound.html
by Oak Ridge National Laboratory
Oak Ridge National Laboratory researchers used the nation's fastest supercomputer to map the molecular vibrations of an important but little-studied uranium compound produced during the nuclear fuel cycle for results that could lead to a cleaner, safer world.

The study by researchers from ORNL, Savannah River National Laboratory and the Colorado School of Mines used simulations conducted on ORNL's Summit supercomputer and state-of-the-art neutron spectroscopy experiments conducted at the Spallation Neutron Source to identify key spectral features of uranium tetrafluoride hydrate, or UFH, a little-studied byproduct of the nuclear fuel cycle. The findings may enable better detection of this environmental pollutant and better understanding of how environmental conditions influence the chemical behavior of fuel cycle materials.

"In this kind of work, we don't have the luxury of choosing what kinds of materials we work with," said Andrew Miskowiec, an ORNL physicist and lead author of the study, published in The Journal of Physical Chemistry C. "We're often dealing with small quantities or even just particles of byproducts and degraded material that no one intended to make of compounds that we don't know much about. We need to know: If we found this material in the field, how would we recognize it?"
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Researchers unravel the active phase in catalytic carbon dioxide reduction to methanol
https://phys.org/news/2022-05-unravel-p ... oxide.html
by Stockholm University
Researchers at Stockholm University have for the first time been able to study the surface of a copper-zinc catalyst when carbon dioxide is reduced to methanol. The results are published in the scientific journal Science. A better knowledge of the catalytic process and the possibility of finding even more efficient materials opens the door for a green transition in the chemical industry.

Methanol is currently one of the most important petrochemical basic chemicals, with an annual production of 110 million metric tons, and can be converted into tens of thousands of different products and used for the manufacture of, for example, plastics, detergents, pharmaceuticals and fuels. Methanol also has the potential to become a future energy carrier where, for example, aviation fuel can be produced using captured carbon dioxide and hydrogen from electrolysis of water instead of using natural gas. A future green transformation of the chemical industry, similar to the one with green steel, where wind or solar energy drives electrolytic cells is therefore a possibility.

"The challenge has been to experimentally investigate the catalyst surface with surface-sensitive methods under real reaction conditions at relatively high pressures and temperatures. Those conditions have for many years not been achievable and different hypotheses about zinc being available as oxide, metallic or in alloy with copper arose but could not be unambiguously verified," says Anders Nilsson, professor of chemical physics at Stockholm University.
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