Space agencies and private companies are already developing plans to send humans to Mars in the next few years, eventually leading to its colonization. And with the increasing number of discovered Earth-like planets around nearby stars, long-distance space travel is becoming increasingly relevant.
However, it is not easy for humans to survive in space for long periods of time. One of the major challenges of long-distance spaceflight is transporting enough oxygen for astronauts to breathe and enough fuel to operate complex electronics. Unfortunately, there is practically no oxygen in space, so it needs to be stored on Earth.
But new research published in Nature Communications shows that it is possible to produce hydrogen (for fuel) and oxygen (for breathing) from water using only semiconductor material, sunlight (or starlight) and weightlessness, making long-distance travel more feasible.
Using the unlimited resource of the Sun to power our everyday life- one of the most global challenges on Earth. As we slowly move away from oil and toward renewable energy sources, researchers are interested in the possibility of using hydrogen as a fuel. The best way to do this would be to separate water (H2O) into its components: hydrogen and oxygen. This is possible using a process known as electrolysis, which involves passing a current through water containing some soluble electrolyte (such as salt - approx. translation). As a result, water breaks down into oxygen and hydrogen atoms, which are each released at its own electrode.
Electrolysis of water.
Although this method is technically possible and has been known for centuries, it is still not readily available on Earth because we need more hydrogen-related infrastructure - such as hydrogen refueling stations.
Hydrogen and oxygen obtained from water in this way can also be used as fuel in spaceship. Launching a rocket with water would actually be much safer than launching it with extra propellant and oxygen on board, since the mixture could be explosive in an accident. Now in space special technology will be able to split water into hydrogen and oxygen, which, in turn, can be used to support breathing and the functionality of electronics (for example, using fuel cells).
There are two options for this. One of them is electrolysis, as on Earth, using electrolytes and solar panels to receive current. But, alas, electrolysis is a very energy-intensive process, and energy in space is already “worth its weight in gold.”
An alternative is to use photocatalysts, which work by absorbing photons by a semiconductor material placed in water. The photon energy “knocks” an electron out of the material, leaving a “hole” in it. A free electron can interact with protons in water to form hydrogen atoms. Meanwhile, the “hole” can absorb electrons from the water to form protons and oxygen atoms. 
The process of photocatalysis in terrestrial conditions and in microgravity (a million times less than on Earth). As can be seen, in the second case the number of gas bubbles appearing is greater.
This process can be reversed. Hydrogen and oxygen can be recombined (combined) using fuel cell, as a result of which the amount spent on photocatalysis will be “returned” solar energy and water is formed. Thus, this technology is the real key to long-distance space travel.
The process using photocatalysts is the best option for space travel, since the equipment weighs much less than that needed for electrolysis. In theory, working with it in space is also easier. This is partly due to the fact that the intensity of sunlight outside the Earth's atmosphere is much higher, since in the latter a fairly large part of the light is absorbed or reflected on the way to the surface.
In a new study, scientists dropped a fully functioning photocatalysis experimental setup from a 120-meter-tall tower, creating conditions called microgravity. As objects fall to Earth in free fall, the effect of gravity decreases (but gravity itself does not disappear, which is why it is called microgravity, not no gravity - approx. translation), since there are no forces that compensate for the Earth’s gravity - thus, during the fall, conditions are created in the installation as on the ISS.
Experimental setup and experimental process.
Researchers were able to show that under such conditions it is indeed possible to split water. However, since this process produces gas, bubbles form in the water. An important task is to get rid of the catalyst material bubbles as they interfere with the gas creation process. On Earth, gravity causes bubbles to float to the surface (water near the surface is denser than bubbles, allowing them to float on the surface), freeing up space at the catalyst for further bubbles to form.
In zero gravity this is impossible, and gas bubbles remain on or near the catalyst. However, the scientists adjusted the shape of the catalyst at the nanoscale, creating pyramidal zones where the bubble could easily break away from the top of the pyramid and enter the water without interfering with the process of formation of new bubbles.
But one problem remains. In the absence of gravity, the bubbles will remain in the liquid even though they have been forced to leave the catalyst. Gravity allows the gas to easily escape from the liquid, which is critical for the use of pure hydrogen and oxygen. Without gravity, no gas bubbles float on the surface and separate from the liquid - instead, the equivalent of foam forms.
This dramatically reduces the efficiency of the process by blocking the catalysts or electrodes. Engineering solutions around this problem will be key to the successful implementation of the technology in space - one of possible solutions consists in rotating the installation: in this way, centrifugal forces will create artificial gravity. But nevertheless, thanks to this new research, we are one step closer to long-duration human spaceflight.
Hydrogen (H) is very light chemical element, with a content of 0.9% by weight in the Earth's crust, and 11.19% in water.
Characteristics of hydrogen
It is the first among gases in lightness. Under normal conditions, it is tasteless, colorless, and absolutely odorless. When it enters the thermosphere, it flies off into space due to its low weight.
In the entire universe, it is the most numerous chemical element (75% of the total mass of substances). So much so that many stars in outer space are made entirely of it. For example, the Sun. Its main component is hydrogen. And heat and light are the result of the release of energy during the fusion of material nuclei. Also in space there are entire clouds of its molecules of various sizes, densities and temperatures.
Physical properties
High temperature and pressure significantly change its qualities, but under normal conditions it:
It has high thermal conductivity when compared with other gases,
Non-toxic and poorly soluble in water,
With a density of 0.0899 g/l at 0°C and 1 atm.,
Turns into liquid at a temperature of -252.8°C
Becomes hard at -259.1°C.,
Specific heat of combustion 120.9.106 J/kg.
Required to transform into liquid or solid state high blood pressure and very low temperatures. In a liquefied state, it is fluid and light.
Chemical properties
Under pressure and upon cooling (-252.87 degrees C), hydrogen acquires a liquid state, which is lighter in weight than any analogue. It takes up less space in it than in gaseous form.
It is a typical non-metal. In laboratories, it is produced by reacting metals (such as zinc or iron) with dilute acids. Under normal conditions it is inactive and reacts only with active non-metals. Hydrogen can separate oxygen from oxides, and reduce metals from compounds. It and its mixtures form hydrogen bonds with certain elements.
The gas is highly soluble in ethanol and in many metals, especially palladium. Silver does not dissolve it. Hydrogen can be oxidized during combustion in oxygen or air, and when interacting with halogens.
When it combines with oxygen, water is formed. If the temperature is normal, then the reaction proceeds slowly; if it is above 550°C, it explodes (it turns into detonating gas).
Finding hydrogen in nature
Although there is a lot of hydrogen on our planet, it is not easy to find in its pure form. A little can be found during volcanic eruptions, during oil production and where organic matter decomposes.
More than half of the total amount is in the composition with water. It is also included in the structure of oil, various clays, flammable gases, animals and plants (presence in every living cell is 50% by the number of atoms).
Hydrogen cycle in nature
Every year, a colossal amount (billions of tons) of plant residues decomposes in water bodies and soil, and this decomposition releases a huge mass of hydrogen into the atmosphere. It is also released during any fermentation caused by bacteria, combustion and, along with oxygen, participates in the water cycle.
Hydrogen Applications
The element is actively used by humanity in its activities, so we have learned to obtain it on an industrial scale for:
Meteorology, chemical production;
Margarine production;
As rocket fuel (liquid hydrogen);
Electric power industry for cooling electric generators;
Welding and cutting of metals.
A lot of hydrogen is used in the production of synthetic gasoline (to improve the quality of low-quality fuel), ammonia, hydrogen chloride, alcohols, and other materials. Nuclear energy actively uses its isotopes.
The drug “hydrogen peroxide” is widely used in metallurgy, the electronics industry, pulp and paper production, for bleaching linen and cotton fabrics, for the production of hair dyes and cosmetics, polymers and in medicine for the treatment of wounds.
The "explosive" nature of this gas can become a deadly weapon - hydrogen bomb. Its explosion is accompanied by the release of a huge amount of radioactive substances and is destructive for all living things.
Contact of liquid hydrogen and the skin can cause severe and painful frostbite.
Generalizing scheme "HYDROGEN"
I. Hydrogen is a chemical elementa) Position in PSHE
- serial number No. 1
- period 1
- group I (main subgroup “A”)
- relative mass Ar(H)=1
- Latin name Hydrogenium (giving birth to water)
b) The prevalence of hydrogen in nature
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Hydrogen is a chemical element. |
IN earth's crust (lithosphere and hydrosphere) – 1% by weight (10th place among all elements) |
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ATMOSPHERE - 0.0001% by number of atoms |
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The most common element in the universe – 92% of all atoms (main component stars and interstellar gas) |
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Hydrogen is a chemical element |
In connections |
H 2 O - water(11% by weight) |
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CH 4 – methane gas(25% by weight) |
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Organic matter(oil, flammable natural gases and others) In animal and plant organisms(that is, in the composition of proteins, nucleic acids, fats, carbohydrates and others) In the human body on average it contains about 7 kilograms of hydrogen. |
c) Valence of hydrogen in compounds
II. Hydrogen is a simple substance (H 2)
Receipt
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1. Laboratory (Kipp apparatus) A) Interaction of metals with acids: Zn+ 2HCl = ZnCl 2 + H 2 salt B) Interaction of active metals with water: 2Na + 2H 2 O = 2NaOH + H 2 base |
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2. Industry · Electrolysis of water email current 2H 2 O =2H 2 + O 2 · From natural gas t,Ni CH 4 + 2H 2 O=4H 2 +CO 2 |
Finding hydrogen in nature.
Hydrogen is widespread in nature, its content in the earth's crust (lithosphere and hydrosphere) is 1% by mass and 16% by number of atoms. Hydrogen is part of the most common substance on Earth - water (11.19% of Hydrogen by mass), in the composition of compounds that make up coal, oil, natural gases, clays, as well as animal and plant organisms (that is, in the composition of proteins, nucleic acids , fats, carbohydrates and others). Hydrogen is extremely rare in its free state; it is found in small quantities in volcanic and other natural gases. Minor amounts of free Hydrogen (0.0001% by number of atoms) are present in the atmosphere. In near-Earth space, Hydrogen in the form of a flow of protons forms the internal (“proton”) radiation belt of the Earth. In space, Hydrogen is the most abundant element. In the form of plasma, it makes up about half the mass of the Sun and most stars, the bulk of the gases of the interstellar medium and gaseous nebulae. Hydrogen is present in the atmosphere of a number of planets and in comets in the form of free H 2, methane CH 4, ammonia NH 3, water H 2 O, and radicals. In the form of a stream of protons, Hydrogen is part of the corpuscular radiation of the Sun and cosmic rays.
There are three isotopes of hydrogen:
a) light hydrogen - protium,
b) heavy hydrogen – deuterium (D),
c) superheavy hydrogen – tritium (T).
Tritium is an unstable (radioactive) isotope, so it practically does not occur in nature. Deuterium is stable, but it is very small: 0.015% (of the mass of all terrestrial hydrogen).
Valence of hydrogen in compounds
In compounds, hydrogen exhibits valency I.
Physical properties of hydrogen
The simple substance hydrogen (H 2) is a gas, lighter than air, colorless, odorless, tasteless, boiling point = – 253 0 C, hydrogen is insoluble in water, flammable. Hydrogen can be collected by displacing air from a test tube or water. In this case, the test tube must be turned upside down.
Hydrogen production
In the laboratory, hydrogen is produced as a result of the reaction
Zn + H 2 SO 4 = ZnSO 4 + H 2.
Instead of zinc, you can use iron, aluminum and some other metals, and instead of sulfuric acid, you can use some other dilute acids. The resulting hydrogen is collected in a test tube by displacing water (see Fig. 10.2 b) or simply in an inverted flask (Fig. 10.2 a).
In industry, hydrogen is produced in large quantities from natural gas (mainly methane) by reacting it with water vapor at 800 °C in the presence of a nickel catalyst:
CH 4 + 2H 2 O = 4H 2 +CO 2 (t, Ni)
or treat coal at high temperature with water vapor:
2H 2 O + C = 2H 2 + CO 2. (t)
Pure hydrogen is obtained from water by decomposing it electric shock(subjecting to electrolysis):
2H 2 O = 2H 2 + O 2 (electrolysis).
Astrophysicists know that star formation requires fuel. The current theory is that rivers of hydrogen - known as "cold streams" - could be a kind of ferry of hydrogen through intergalactic space and therefore fuel the process of star formation.
Spiral galaxies, like our Milky Way, tend to have a fairly quiet but steady rate of star formation. Other galaxies, such as NGC 6946, which is located about 22 million light years from Earth on the border of the constellations Cepheus and Cygnus, are much more active in this regard. This raises the question of what provides the breeding ground for sustained star formation in this and similar spiral galaxies.
Previous studies of the nearby galactic space around NGC 6946 from the WSRT telescope in the Netherlands revealed an extended halo of hydrogen. However, the cold stream could have been formed by hydrogen from a completely different source - gas from intergalactic space that was never heated to high temperatures by the birth of stars.
Using the Green Bank Telescope (GBT), Pisano was able to detect the glow emitted by neutral hydrogen connecting NGC 6946 to its cosmic neighbors. This signal was simply below the detection threshold of other telescopes, but the unique capabilities of the GBT allowed the scientist to detect this faint radiation.
Astronomers have long hypothesized that large galaxies could obtain a constant supply of cold hydrogen by pumping it from other less massive companions.
Further research will help confirm the nature of this observation and help shed light on the possible role that cold streams play in the evolution of galaxies.
On Earth - oxygen, in space - hydrogen
The Universe contains the most hydrogen (74% by mass). It has been preserved since the Big Bang. Only a small part of the hydrogen managed to turn into heavier elements in stars. On Earth, the most abundant element is oxygen (46–47%). Most of it is bound in the form of oxides, primarily silicon oxide (SiO 2). Earth's oxygen and silicon originated in massive stars that existed before the birth of the Sun. At the end of their lives, these stars exploded in supernovae and ejected the elements they formed into space. Of course, the explosion products contained a lot of hydrogen and helium, as well as carbon. However, these elements and their compounds are highly volatile. Near the young Sun, they evaporated and were blown out by radiation pressure to the outskirts of the Solar System.
Ten Most Common Elements in the Milky Way Galaxy*
* Mass fraction per million.
