Oxygen
Element 8 · chemical symbol: O
These Vrulum profiles mention Oxygen by name. Read each profile for its specific context; a mention alone does not establish composition, performance or use of the pure element.
For periodic-table data and other properties, consult the Royal Society of Chemistry periodic table.
Related technology profiles
Artificial photosynthesis
Artificial leaves are devices that use sunlight to split water into hydrogen and oxygen in one integrated unit. Laboratory modules have reached about 11% solar-to-hydrogen efficiency under one-sun illumination, but durability and outdoor performance at useful scale have not yet been shown.
Biochar
Biochar is a carbon-rich solid made by heating biomass with little or no oxygen, which can be added to soil to store carbon for a long time. Field and laboratory evidence suggests much of its carbon persists for decades or longer, but yield effects vary widely by region and soil, and credited volumes are reported inconsistently.
Car electronics and engine control
Electronic control of engines and vehicle systems grew from Bosch's electronic fuel injection in 1967 to the software-defined vehicles discussed today. Several of these steps were prompted by emissions rules, and electronic fuel injection, engine control units, the CAN bus and OBD diagnostics are now standard in cars.
Carbon-storing building materials
Carbon-storing building materials add carbon-rich biochar to concrete, or cure cement-based products with CO2 so that the gas becomes solid minerals. Pilot and small field trials were reported in 2025, but whether they give a net climate benefit over a full lifecycle is not yet established.
Catalytic converters
A catalytic converter is a device in a petrol car's exhaust that uses a catalyst to turn carbon monoxide, unburnt fuel and nitrogen oxides into less harmful gases. It has been fitted to new petrol cars in the United States since the mid-1970s, and it depends on lead-free petrol.
Crops with boosted photosynthesis
Plant scientists are engineering crops to waste less light energy and carbon, either by recovering faster from the protective heat release that follows shade or by bypassing photorespiration. Several replicated field trials report yield or biomass gains, but the soybean yield result is disputed and no independent multi-site replication is confirmed in the sources reviewed.
Cultivated meat
Cultivated meat is produced by growing animal cells in bioreactors instead of raising whole animals. US, UK, and Australian and New Zealand regulators have started product-specific reviews, but high culture media costs and the need for structures to support thick tissue remain major hurdles.
Electrolysers for low-carbon hydrogen
Electrolysers use electricity to split water into hydrogen and oxygen. Alkaline and proton-exchange-membrane systems are commercially available, while solid-oxide and anion-exchange-membrane designs offer different trade-offs and maturity levels. Hydrogen is only low emissions when the electricity and wider supply chain are low emissions; project announcements and electrolyser capacity do not by themselves establish climate benefit or delivered hydrogen output.
Engineered living therapeutics
Engineered living therapeutics use genetically modified microbes, mainly bacteria, to make a therapeutic molecule and release it near the disease site. Several candidates have reached early human studies, but the clinical evidence is small and most results still come from cell and animal experiments.
Hydrogen aircraft
Hydrogen aircraft would use hydrogen either in a fuel cell that drives electric propellers or in a modified gas turbine. Engine and fuel-cell tests, an uncrewed drone flight and airport ground trials have taken place, but no hydrogen passenger aircraft has entered service and the climate benefit depends on how the hydrogen is made.
Industrial steelmaking
Industrial steelmaking turns molten iron into steel by removing carbon and other impurities. The main methods date from the Bessemer process of 1856 and the open-hearth furnace, and today's routes are the basic oxygen furnace and the electric arc furnace.
Iron-air batteries
Iron-air batteries are a long-duration storage design that uses iron, oxygen from the air and a water-based electrolyte, aimed at delivering power for days rather than hours. In a 2025 California Energy Commission report, kilowatt-scale prototype modules discharged for more than 100 hours under controlled tests, but round-trip efficiency is not public and no multi-day commercial plant has yet been shown to operate.
Lab-grown red blood cells
Lab-grown red blood cells are made from stem cells as a possible future transfusion product. The UK RESTORE trial has completed its final mini-dose transfusions and is closed to recruitment; results are expected in late 2026 or early 2027. Whether manufactured cells survive longer than donated cells is not yet known, and producing enough cells affordably for routine care remains a major challenge.
Lunar resource extraction
Lunar resource extraction means producing oxygen, water and metals from lunar regolith and ice, so that missions need to launch less material from Earth. Oxygen has been made from simulated lunar soil in Earth tests, and water has been detected remotely near the Moon's south pole, but no lunar extraction has yet been shown on the Moon.
Making oxygen and fuel on Mars
NASA's MOXIE instrument on the Perseverance rover made oxygen from the Martian atmosphere over 16 runs, reaching 12 grams per hour at its most efficient. Making methane fuel and extracting water on Mars, and scaling oxygen production for crewed missions, remain at model, proposal or concept stage.
Nitrogen-fixing cereals
Nitrogen-fixing cereals would take nitrogen from the air through engineered plants or root-associated microbes, reducing the need for synthetic fertiliser. Some commercial microbial products are sold for maize, but their field results vary, and engineering cereals to fix nitrogen themselves has so far only reached early laboratory steps.
Plant microbial fuel cells
Plant and soil microbial fuel cells harvest small electrical currents from microbes that live around plant roots or in soil. Published studies since 2008 report small outputs. Later work from 2024 and 2026 describes longer runs and sensor use, but its full results could not be checked, so its figures are treated as unverified.
Protein made from air and electricity
Gas fermentation grows microbes on hydrogen, carbon dioxide and oxygen, then dries the cells into a protein powder for food or feed. One producer reports a food approval in Singapore and a self-affirmed GRAS conclusion in the United States, but published cost and life-cycle studies depend heavily on low-carbon electricity and are mostly modelled rather than measured at scale.
Recirculating aquaculture systems
Recirculating aquaculture systems (RAS) raise fish in land-based tanks that filter and reuse most of their water. They need large amounts of energy, are costly to build, and have suffered failures and closures.
Seawater electrolysis
Seawater electrolysis uses electricity to split seawater directly into hydrogen and oxygen, without first removing the salt. Laboratory and small-device studies report long test runs, but no complete system has yet been shown to be cheaper, cleaner or more reliable than purifying water first.
Smart contact lenses
Smart contact lenses are soft lenses with sensors or micro-displays built in. One sensing lens, Sensimed's Triggerfish, has US marketing authorisation to help clinicians time eye pressure checks in glaucoma, but tear glucose sensing and display lenses have only been tested in small early studies and in animals.
Solar sails
Solar sails are large, very thin reflective membranes that change a spacecraft's speed or orbit using the small, steady push of sunlight rather than fuel. Japan's IKAROS (2010) and NASA's LightSail 2 (2019) showed the method works in space, but the push is very small and the sail must unfold and survive in orbit.