Designing layered oxide materials for sodium-ion batteries

Lithium cobalt oxide is a layered metal oxide that has attracted great attention to develop rechargeable batteries. Sodium-ion batteries can store grid-scale energy due to the natural abundance of sodium. The composition ...

Energy & Green Tech

A blast of gas for better solar cells

Treating silicon with carbon dioxide gas in plasma processing brings simplicity and control to a key step for making solar cells.

Electronics & Semiconductors

Radiation-immune and repairable chips to fabricate durable electronics

To operate safely and reliably in outdoor environments, electronic devices should be resistant to a wide variety of external factors, including radiation. In fact, high-energy radiation can damage several components of field-effect ...

Electronics & Semiconductors

Lightweight green supercapacitors could quickly charge devices

In a new study, researchers at Texas A&M University have described their novel plant-based energy storage device that could charge even electric cars within a few minutes in the near future. Furthermore, they said their devices ...

Energy & Green Tech

Decades-old mystery of lithium-ion battery storage solved

For years, researchers have aimed to learn more about a group of metal oxides that show promise as key materials for the next generation of lithium-ion batteries because of their mysterious ability to store significantly ...

Energy & Green Tech

Researchers advance fuel cell technology

Washington State University researchers have made a key advance in solid oxide fuel cells (SOFCs) that could make the highly energy-efficient and low-polluting technology a more viable alternative to gasoline combustion engines ...

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An oxide ( /ˈɒksaɪd/) is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2.

Most of the Earth's crust consists of solid oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon monoxide and carbon dioxide. Even materials that are considered to be pure elements often contain a coating of oxides. For example, aluminium foil has a thin skin of Al2O3 that protects the foil from further corrosion.

Virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen (or simply air), some elements—lithium, sodium, potassium, rubidium, caesium, strontium and barium—react rapidly, even dangerously, to give the hydroxides. In part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i.e., native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, and solutions of potassium and sodium, so called NaK are used to deoxygenate and dehydrate some organic solvents. The surface of most metals consists of oxides and hydroxides in the presence of air. A well known example is aluminium foil, which is coated with a thin film of aluminium oxide that passivates the metal, slowing further corrosion. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising. Although solid magnesium and aluminium react slowly with oxygen at STP, they, like most metals, will burn in air, generating very high temperatures. Finely grained powders of most metals can be dangerously explosive in air. Consequently, they are often used in Solid-fuel rockets.

In dry oxygen, iron readily forms iron(II) oxide, but the formation of the hydrated ferric oxides, Fe2O3−2x(OH)x, that mainly comprise rust, typically requires oxygen and water. The production of free oxygen by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the economically important iron ore hematite.

Due to its electronegativity, oxygen forms chemical bonds with almost all elements to give the corresponding oxides. Noble metals (such as gold or platinum) resist direct chemical combination with oxygen, and substances like gold(III) oxide must be generated by indirect routes.

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