Tag: oxidation

Explosive Prevention for 1,000km Next-Gen Battery!

Explosive Prevention for 1,000km Next-Gen Battery!

A solution to the gas-filling problem of the next-generation long-distance battery1) has emerged.
A team led by Professor Lee Hyun-wook of UNIST’s Department of Energy and Chemical Engineering has identified the cause of Oxygen generation in olig Lithium of a new anode material for batteries and presented material design principles to solve this problem.

Overlithium materials can theoretically store 30% to 70% more energy in batteries than before through high-pressure charging of 4.5V or higher. In terms of electric vehicle mileage, you can go up to 1,000 kilometers on a single charge. However, this material has a problem of increasing the risk of explosion as Oxygen (O-2) held inside the material is oxidized and released as gas (O2) during the actual high-pressure charging process.

The research team analyzed that Oxygen is oxidized near 4.25V, causing partial structural deformation and releasing Oxygen gas. They proposed an electrode material design method that fundamentally prevents the oxidation of Oxygen. This strategy involves replacing some of the transition metals2) of Lithium materials with transition metal elements with lower electronegativity.

The difference in electronegativity between the two metal elements causes the number of available electrons in the transition metal to increase, and Oxygen does not oxidize when electrons are concentrated around the highly electronegativity element. On the other hand, when the number of available electrons in the transition metal is insufficient, Oxygen gives electrons instead. It is oxidized to be discharged in the form of a gas.

The first author, Kim Min-ho (Currently a postdoctoral researcher at UCLA), explained “the difference between existing research that has focused on stabilizing Oxygen and preventing it from being discharged in the form of gas, whereas present research has focused on preventing the oxidizing process itself.”

In addition, this change in electron density increases the charging voltage through an Inductive Effect3), thereby increasing the high energy density attainable. Since the energy density is proportional to the number of available electrons and the charging voltage, it is possible to store more energy per unit weight of the battery to replace the transition metal. This phenomenon is similar to the principle that if there’s more water in the dam and the drop is more significant, more energy is stored.

The researchers experimentally confirmed the transition metal substitution strategy’s inhibitory effect on Oxygen oxidation. Accelerator-based X-ray analysis showed that the generation of Oxygen gas was significantly reduced when a part of Ruthenium was replaced with Nickel. Furthermore, they theoretically demonstrated that charge rearrangement occurs through density functional calculation (DFT).

This study was conducted by Professor Seo Dong-hwa of KAIST, Chung-Ang University, Pohang Accelerator Laboratory, Professor Yu Zhang Li of UCLA, UC Berkeley, and Lawrence Berkeley Research Institute. The accelerator-based X-ray analysis was conducted by Professor Jang Hae-sung of Chung-Ang University (Co-first author), and the DFT theoretical calculation was led by Dr. Lee Eun-ryul (Co-first author) of the Lawrence Berkeley Institute in the United States.

Professor Lee Hyun-wook said, “We presented the direction of material development to cathode material researchers by librarying technology through various experiments and theoretical analysis,” adding, “It will help to develop long-distance driving battery materials without explosions with increased energy density.”

The study was carried out with the support of the National Research Foundation of Korea (NRF)’s international cooperation and development project on source technology. The results were published online on Feb. 19 in ‘Science Advances’, a sister paper of the world-renowned journal ‘Science’ published by the American Science Association (AAAS).

Read more on PAL website

New biocatalyst could more efficiently split water molecules

New biocatalyst could more efficiently split water molecules

Experiment carried out on Sirius shed light on reaction fundamental to the production of hydrogen fuel


A recent experiment at Sirius, the Brazilian synchrotron light source at the Brazilian Center for Research in Energy and Materials (CNPEM) in Campinas, São Paulo (see Pesquisa FAPESP issue 269) showed how a certain biological catalyst can more efficiently split water molecules (H2O) using electrolysis. This reaction, an electrochemical process that uses electricity to break down water into the elements that comprise it, is very significant because it produces not only oxygen but also hydrogen, considered the fuel of the future by many specialists because it does not emit any polluting gases when it is utilized (see Pesquisa FAPESP issue 314).

“We discovered that when some enzymes present in nature like bilirubin oxidase (BOD) are manipulated in the lab, they can accelerate the reaction to split water,” states chemist Frank Nelson Crespilho, a professor at the University of São Paulo’s São Carlos Institute of Chemistry (IQSC-USP) who led the study. “We didn’t know why this happened; thanks to new equipment developed specifically for Sirius, we were able to observe how this enzyme, BOD, behaves during the process of oxidation in water. We found that the copper atoms within it are relevant to this reaction.”

Crespilho expects this advance to pave the way for science to get inspiration from the part of the enzyme that accelerated the reaction. “It is important for us to recognize the important regions of BOD, since today synthetic chemists that work in materials production can copy and synthesize this part of the enzyme in the laboratory. This will make the catalyst much more affordable, with a much broader range of potential applications,” he adds. Most of the catalysts used in this process utilize noble metals like platinum and iridium, making large-scale application unfeasible due to the cost involved. An article describing the experiment written by Crespilho’s team, which includes the researchers Graziela Sedenho, Rafael Colombo, Thiago Bertaglia, and Jessica Pacheco, was published in October in the journal Advanced Energy Materials. Scientists from the Brazilian Synchrotron Light National Laboratory (LNLS) also participated in the study.

Read more on the LNLS website

Image: Researcher manipulates electrochemical cell used in experiment

A timely solution for the photosynthetic oxygen evolving clock

A timely solution for the photosynthetic oxygen evolving clock

XFEL Hub collaboration reveals the intermediates of the photosynthetic water oxidation clock

A large international collaborative effort aided by the XFEL Hub at Diamond Light Source has generated the most detailed time-resolved studies to date of a key protein involved in photosynthesis. The pioneering work, recently published in Nature, shows how photosystem II harnesses light energy to produce oxygen – insights that could direct a next generation of photovoltaic cells. 
>Read more on the Diamond Light Source website

Image: this figure is issued from a video you can watch here.

Unraveling the Complexities of Auto-Oxidation

Unraveling the Complexities of Auto-Oxidation

A better understanding of auto-oxidation reaction mechanisms could lead to better engines, less air pollution, and improved climate models.

Oxygen plays a key role in chemical reactions that produce pollutants in the atmosphere and that fuel combustion engines. In these reactions, auto-oxidation (spontaneous oxidation in air or in the presence of oxygen) produces highly oxygenated molecules.

For example, volatile organic compounds (VOCs)—gas molecules emitted from vehicles, factories, and power plants (as well as living plants)—undergo a sequence of auto-oxidation reactions with the surrounding air, forming highly oxygenated molecules that contribute to air pollution, affecting health and climate. The same highly oxygenated molecules are also produced during the ignition of fuels in advanced combustion engines; controlling their formation and destruction processes can help to develop higher-efficiency engines.

However, because these highly oxygenated molecules are very reactive and decompose quickly, determining their identities has been difficult.

>Read more on the ALS website

Image: Illustration of the jet-stirred reactor used in this experiment. Jet nozzles in the reaction chamber (center) generate turbulence for mixing the incoming fuel molecules with oxidizer (lower right). After the fuels react, the products exit the apparatus (upper left) to be analyzed by advanced mass spectrometry.
Credit: Ahmed Najjar

Scientists decipher key principle behind reaction of metalloenzymes

Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how important bioinorganic electron transfer systems operate. Using a combination of very different, time-resolved measurement methods at DESY’s X-ray source PETRA III and other facilities, the scientists were able to show that so-called pre-distorted states can speed up photochemical reactions or make them possible in the first place. The group headed by Sonja Herres-Pawlis from the RWTH Aachen University  Michael Rübhausen from the University of Hamburg and Wolfgang Zinth from Munich’s Ludwig Maximilian University, is presenting its findings in the journal Nature Chemistry.

The scientists had studied the pre-distorted, “entatic” state using a model system. An entatic state is the term used by chemists to refer to the configuration of a molecule in which the normal arrangement of the atoms is modified by external binding partners such that the energy threshold for the desired reaction is lowered, resulting in a higher speed of reaction. One example of this is the metalloprotein plastocyanin, which has a copper atom at its centre and is responsible for important steps in the transfer of electrons during photosynthesis. Depending on its oxidation state, the copper atom either prefers a planar configuration, in which all the surrounding atoms are arranged in the same plane (planar geometry), or a tetrahedral arrangement of the neighbouring ligands. However the binding partner in the protein forces the copper atom to adopt a sort of intermediate arrangement. This highly distorted tetrahedron allows a very rapid shift between the two oxidation states of the copper atom.

>Read more on the PETRA III website

Image Caption: Entatic state model complexes optimize the energies of starting and final configuration to enable fast reaction rates (illustrated by the hilly ground). The work demonstrates that the entatic state principle can be used to tune the photochemistry of copper complexes.
Credit: RWTH Aachen, Sonja Herres-Pawlis