Editing Hydrogen (section)

== Applications ==

{{See also|Hydrogen economy}}
[[File:The_Hydrogen_Ladder,_Version_5.0.jpg|thumb|520px|Some projected uses in the medium term, but analysts disagree<ref>{{Cite web |last=Barnard |first=Michael |date=2023-10-22 |title=What's New On The Rungs Of Liebreich's Hydrogen Ladder? |url=https://cleantechnica.com/2023/10/22/whats-new-on-the-rungs-of-liebreichs-hydrogen-ladder/ |access-date=2024-03-10 |website=CleanTechnica |language=en-US}}</ref>]]

=== Petrochemical industry ===
Large quantities of {{chem2|H2}} are used in the "upgrading" of [[fossil fuels]]. Key consumers of {{chem2|H2}} include [[hydrodesulfurization]], and [[hydrocracking]]. Many of these reactions can be classified as [[hydrogenolysis]], i.e., the cleavage of bonds by hydrogen. Illustrative is the separation of sulfur from liquid fossil fuels:<ref name=KO>{{cite book |doi=10.1002/0471238961.0825041803262116.a01.pub2 |chapter=Hydrogen |title=Kirk-Othmer Encyclopedia of Chemical Technology |date=2001 |last1=Baade |first1=William F. |last2=Parekh |first2=Uday N. |last3=Raman |first3=Venkat S. |isbn=9780471484943 }}</ref><ref name="UllmannHuse">{{cite book |author1=Peter Häussinger |author2=Reiner Lohmüller |author3=Allan M. Watson |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |publisher=Wiley |isbn=9783527306732 |language=en |chapter= Hydrogen, 6. Uses |doi=10.1002/14356007.o13_o07}}</ref>
:{{chem2|R2S + 2 H2 → H2S + 2 RH}}

=== Hydrogenation ===
[[Hydrogenation]], the addition of {{chem2|H2}} to various substrates, is done on a large scale. Hydrogenation of {{chem2|N2}} produces ammonia by the [[Haber process]]:<ref name="UllmannHuse" />
:{{chem2|N2 + 3 H2 → 2 NH3}}
This process consumes a few percent of the energy budget in the entire industry and is the biggest consumer of hydrogen. The resulting ammonia is used in fertilizers critical to the supply of protein consumed by humans.<ref name="Smil_2004_Enriching">{{cite book |last1=Smil |first1=Vaclav |title=Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production |date=2004 |publisher=MIT |location=Cambridge, MA |isbn=978-0-262-69313-4 |edition=1st}}</ref> Hydrogenation is also used to convert [[unsaturated fat]]s and [[vegetable oil|oils]] to saturated fats and oils. The major application is the production of [[margarine]]. [[Methanol]] is produced by hydrogenation of carbon dioxide; the mixture of hydrogen and carbon dioxide used for this process is known as [[syngas]]. It is similarly the source of hydrogen in the manufacture of [[hydrochloric acid]]. {{chem2|H2}} is also used as a [[reducing agent]] for the conversion of some [[ore]]s to the metals.<ref>{{cite web|author=Chemistry Operations|date=15 December 2003|url=http://periodic.lanl.gov/1.shtml|title=Hydrogen|publisher=Los Alamos National Laboratory|access-date=5 February 2008|archive-url=https://web.archive.org/web/20110304203439/http://periodic.lanl.gov/1.shtml|archive-date=4 March 2011}}</ref><ref name="housecroft" />

=== Fuel ===
The potential for using hydrogen (H<sub>2</sub>)  as a fuel has been widely discussed. Hydrogen can be used in [[fuel cells]] to produce electricity,<ref>{{cite journal |doi=10.1155/2024/7271748 |title=A Recent Comprehensive Review of Fuel Cells: History, Types, and Applications |date=2024 |last1=Qasem |first1=Naef A. A. |last2=Abdulrahman |first2=Gubran A. Q. |journal=International Journal of Energy Research |issue=1 |doi-access=free |bibcode=2024IJER.202471748Q }}</ref> or burned to generate heat.<ref name="Lewis-2021">{{Cite journal |last=Lewis |first=Alastair C. |date=10 June 2021 |title=Optimising air quality co-benefits in a hydrogen economy: a case for hydrogen-specific standards for NO x emissions |journal=Environmental Science: Atmospheres |language=en |volume=1 |issue=5 |pages=201–207 |bibcode=2021ESAt....1..201L |doi=10.1039/D1EA00037C |doi-access=free}}{{Creative Commons text attribution notice|cc=by3|from this source=yes|url=|authors=|vrt=}}</ref> When hydrogen is consumed in fuel cells, the only emission at the point of use is water vapor.<ref name="Lewis-2021" /> When burned, hydrogen produces relatively little pollution at the point of combustion, but can lead to thermal formation of harmful [[NOx|nitrogen oxides]].<ref name="Lewis-2021" />

If hydrogen is produced with low or zero greenhouse gas emissions ([[green hydrogen]]), it can play a significant role in decarbonizing energy systems where there are challenges and limitations to replacing fossil fuels with direct use of electricity.<ref name="IPCC-20222">{{Cite book |author=IPCC |author-link=IPCC |url=https://ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_FullReport.pdf |title=Climate Change 2022: Mitigation of Climate Change |publisher=Cambridge University Press (In Press) |year=2022 |isbn=9781009157926 |editor1-last=Shukla |editor1-first=P.R. |series=Contribution of Working Group III to the [[IPCC Sixth Assessment Report|Sixth Assessment Report]] of the Intergovernmental Panel on Climate Change |place=Cambridge, UK and New York, NY, US |pages=91–92 |doi=10.1017/9781009157926 |ref={{harvid|IPCC AR6 WG3|2022}} |editor2-last=Skea |editor2-first=J. |editor3-last=Slade |editor3-first=R. |editor4-last=Al Khourdajie |editor4-first=A. |editor5-last=van Diemen |editor5-first=R. |editor6-last=McCollum |editor6-first=D. |editor7-last=Pathak |editor7-first=M. |editor8-last=Some |editor8-first=S. |editor9-last=Vyas |editor9-first=P. |display-editors=4 |editor10-first=R. |editor10-last=Fradera |editor11-first=M. |editor11-last=Belkacemi |editor12-first=A. |editor12-last=Hasija |editor13-first=G. |editor13-last=Lisboa |editor14-first=S. |editor14-last=Luz |editor15-first=J. |editor15-last=Malley}}</ref><ref name="Evans-2020" />

Hydrogen fuel can produce the intense heat required for industrial production of steel, cement, glass, and chemicals, thus contributing to the decarbonization of industry alongside other technologies, such as [[electric arc furnace]]s for steelmaking.<ref>{{Cite web |last=Kjellberg-Motton |first=Brendan |date=2022-02-07 |title=Steel decarbonisation gathers speed {{!}} Argus Media |url=https://www.argusmedia.com/en//news/2299399-steel-decarbonisation-gathers-speed |access-date=2023-09-07 |website=www.argusmedia.com |language=en}}</ref> However, it is likely to play a larger role in providing industrial feedstock for cleaner production of ammonia and organic chemicals.<ref name="IPCC-2022">{{Cite book |author=IPCC |author-link=IPCC |url=https://ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_FullReport.pdf |title=Climate Change 2022: Mitigation of Climate Change |publisher=Cambridge University Press (In Press) |year=2022 |isbn=9781009157926 |editor1-last=Shukla |editor1-first=P.R. |series=Contribution of Working Group III to the [[IPCC Sixth Assessment Report|Sixth Assessment Report]] of the Intergovernmental Panel on Climate Change |place=Cambridge, UK and New York, NY, US |pages=91–92 |doi=10.1017/9781009157926 |ref={{harvid|IPCC AR6 WG3|2022}} |editor2-last=Skea |editor2-first=J. |editor3-last=Slade |editor3-first=R. |editor4-last=Al Khourdajie |editor4-first=A. |editor5-last=van Diemen |editor5-first=R. |editor6-last=McCollum |editor6-first=D. |editor7-last=Pathak |editor7-first=M. |editor8-last=Some |editor8-first=S. |editor9-last=Vyas |editor9-first=P. |display-editors=4 |editor10-first=R. |editor10-last=Fradera |editor11-first=M. |editor11-last=Belkacemi |editor12-first=A. |editor12-last=Hasija |editor13-first=G. |editor13-last=Lisboa |editor14-first=S. |editor14-last=Luz |editor15-first=J. |editor15-last=Malley}}</ref> For example, in [[steelmaking]], hydrogen could function as a clean fuel and also as a low-carbon catalyst, replacing coal-derived [[Coke (fuel)|coke]] (carbon):<ref>{{Cite web |last1=Blank |first1=Thomas |last2=Molly |first2=Patrick |date=January 2020 |title=Hydrogen's Decarbonization Impact for Industry |url=https://rmi.org/wp-content/uploads/2020/01/hydrogen_insight_brief.pdf |url-status=live |archive-url=https://web.archive.org/web/20200922115313/https://rmi.org/wp-content/uploads/2020/01/hydrogen_insight_brief.pdf |archive-date=22 September 2020 |access-date= |publisher=[[Rocky Mountain Institute]] |pages=2, 7, 8}}</ref>
:{{chem2|2FeO  +  C -> 2Fe  +  CO2}}
:::vs
:{{chem2|FeO  +  H2 -> Fe  +  H2O}}
Hydrogen used to decarbonize transportation is likely to find its largest applications in shipping, aviation and, to a lesser extent, heavy goods vehicles, through the use of hydrogen-derived synthetic fuels such as [[Green ammonia|ammonia]] and [[Green methanol|methanol]] and fuel cell technology.<ref name="IPCC-2022" /> For light-duty vehicles including cars, hydrogen is far behind other [[alternative fuel vehicle]]s, especially compared with the rate of adoption of [[battery electric vehicles]], and may not play a significant role in future.<ref>{{Cite journal |last=Plötz |first=Patrick |date=2022-01-31 |title=Hydrogen technology is unlikely to play a major role in sustainable road transport |url=https://www.nature.com/articles/s41928-021-00706-6 |journal=Nature Electronics |language=en |volume=5 |issue=1 |pages=8–10 |doi=10.1038/s41928-021-00706-6 |s2cid=246465284 |issn=2520-1131}}</ref>

[[File:Shuttle Main Engine Test Firing cropped edited and reduced.jpg|thumb|[[Space Shuttle Main Engine]] burning hydrogen with oxygen, produces a nearly invisible flame at full thrust.|alt=A black inverted funnel with blue glow emerging from its opening.]]
[[Liquid hydrogen]] and [[liquid oxygen]] together serve as [[cryogenic propellant]]s in [[liquid-propellant rocket]]s, as in the [[RS-25|Space Shuttle main engines]]. [[NASA]] has investigated the use of [[rocket propellant]] made from atomic hydrogen, boron or carbon that is frozen into solid molecular hydrogen particles suspended in liquid helium. Upon warming, the mixture vaporizes to allow the atomic species to recombine, heating the mixture to high temperature.<ref>{{Cite web |url=https://ntrs.nasa.gov/api/citations/20030005922/downloads/20030005922.pdf |title=NASA/TM—2002-211915: Solid Hydrogen Experiments for Atomic Propellants |access-date=2 July 2021 |archive-date=9 July 2021 |archive-url=https://web.archive.org/web/20210709183557/https://ntrs.nasa.gov/api/citations/20030005922/downloads/20030005922.pdf |url-status=live }}</ref>

Hydrogen produced when there is a surplus of [[Variable renewable energy|variable renewable electricity]] could in principle be stored and later used to generate heat or to re-generate electricity.<ref>{{Cite journal |last1=Palys |first1=Matthew J. |last2=Daoutidis |first2=Prodromos |date=2020 |title=Using hydrogen and ammonia for renewable energy storage: A geographically comprehensive techno-economic study |journal=[[Computers & Chemical Engineering]] |volume=136 |pages=106785 |doi=10.1016/j.compchemeng.2020.106785 |issn=0098-1354 |doi-access=free}}</ref>  It can be further transformed into [[synthetic fuel]]s such as [[ammonia]] and [[methanol]].<ref>{{cite book |author=[[IRENA]] |url=https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2021/March/IRENA_World_Energy_Transitions_Outlook_2021.pdf |title=World Energy Transitions Outlook: 1.5°C Pathway |year=2021 |isbn=978-92-9260-334-2 |pages=12, 22 |archive-url=https://web.archive.org/web/20210611230855/https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2021/March/IRENA_World_Energy_Transitions_Outlook_2021.pdf |archive-date=11 June 2021 |url-status=live}}</ref> Disadvantages of hydrogen fuel include high costs of storage and distribution due to hydrogen's explosivity, its large volume compared to other fuels, and its tendency to make pipes brittle.<ref name="Griffiths-20212"/>

=== Nickel–hydrogen battery ===
The very long-lived, rechargeable [[nickel–hydrogen battery]] developed for satellite power systems uses pressurized gaseous H<sub>2</sub>.<ref>{{Cite book |last=Zimmerman |first=Albert H. |title=Nickel-hydrogen batteries: principles and practice |date=2009 |publisher=Aerospace press |isbn=978-1-884989-20-9 |location=El Segundo, Calif}}</ref> The [[International Space Station]],<ref>{{cite conference|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020070612_2002115777.pdf|work=IECEC '02. 2002 37th Intersociety Energy Conversion Engineering Conference, 2002|pages=45–50|date=July 2002|access-date=11 November 2011|doi=10.1109/IECEC.2002.1391972|title=Validation of international space station electrical performance model via on-orbit telemetry|last1=Jannette|first1=A. G.|last2=Hojnicki|first2=J. S.|last3=McKissock|first3=D. B.|last4=Fincannon|first4=J.|last5=Kerslake|first5=T. W.|last6=Rodriguez|first6=C. D.|isbn=0-7803-7296-4|archive-url=https://web.archive.org/web/20100514100504/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020070612_2002115777.pdf|archive-date=14 May 2010|url-status=live|hdl=2060/20020070612|hdl-access=free}}</ref> [[2001 Mars Odyssey|Mars Odyssey]]<ref>{{cite book|doi=10.1109/AERO.2002.1035418 |date=2002|last1=Anderson|first1=P. M.|last2=Coyne|first2=J. W.|title=Proceedings, IEEE Aerospace Conference |chapter=A lightweight, high reliability, single battery power system for interplanetary spacecraft |isbn=978-0-7803-7231-3|volume=5|pages=5–2433|s2cid=108678345}}</ref> and the [[Mars Global Surveyor]]<ref>{{cite web|url=http://www.astronautix.com/craft/marveyor.htm|title=Mars Global Surveyor|publisher=Astronautix.com|access-date=6 April 2009|archive-url=https://web.archive.org/web/20090810180658/http://www.astronautix.com/craft/marveyor.htm|archive-date=10 August 2009}}</ref> are equipped with nickel-hydrogen batteries. In the dark part of its orbit, the [[Hubble Space Telescope]] is also powered by nickel-hydrogen batteries, which were finally replaced in May 2009,<ref>{{cite web|url=http://www.nasa.gov/mission_pages/hubble/servicing/SM4/main/SM4_Essentials.html|title=Hubble servicing mission 4 essentials|date=7 May 2009|editor=Lori Tyahla|access-date=19 May 2015|publisher=NASA|archive-url=https://web.archive.org/web/20150313073737/http://www.nasa.gov/mission_pages/hubble/servicing/SM4/main/SM4_Essentials.html|archive-date=13 March 2015|url-status=live}}</ref> more than 19 years after launch and 13 years beyond their design life.<ref>{{cite web|url=http://www.nasa.gov/mission_pages/hubble/servicing/series/battery_story.html|title=Extending Hubble's mission life with new batteries|date=25 November 2008|first1=Susan|last1=Hendrix|editor=Lori Tyahla|access-date=19 May 2015|publisher=NASA|archive-url=https://web.archive.org/web/20160305002850/http://www.nasa.gov/mission_pages/hubble/servicing/series/battery_story.html|archive-date=5 March 2016|url-status=live}}</ref>

=== Semiconductor industry ===
Hydrogen is employed to saturate broken ("dangling") bonds of [[amorphous silicon]] and [[amorphous carbon]] that helps stabilizing material properties.<ref>{{cite journal
|last1=Le Comber| first1=P. G.
|title=Hall effect and impurity conduction in substitutionally doped amorphous silicon
|journal=Philosophical Magazine|doi=10.1080/14786437708232943
|volume=35
|issue=5
|pages=1173–1187
|date=1977
|last2=Jones
|first2=D. I.
|last3=Spear
|first3=W. E.|bibcode = 1977PMag...35.1173C }}</ref> Hydrogen, introduced as a unintended side-effect of production, acts as a shallow [[electron donor]] leading to [[N-type semiconductor|n-type]] conductivity in [[ZnO]], with important uses in [[transducers]] and [[phosphors]].<ref>{{cite journal|last=Van de Walle|first=C. G.|title=Hydrogen as a cause of doping in zinc oxide|journal=Physical Review Letters|volume=85|issue=5|doi=10.1103/PhysRevLett.85.1012|pages=1012–1015|date=2000|pmid=10991462|bibcode=2000PhRvL..85.1012V|hdl=11858/00-001M-0000-0026-D0E6-E|url=http://pubman.mpdl.mpg.de/pubman/item/escidoc:741885/component/escidoc:932688/PRL-85-1012-2000.pdf|access-date=1 August 2018|archive-url=https://web.archive.org/web/20170815000602/http://pubman.mpdl.mpg.de/pubman/item/escidoc:741885/component/escidoc:932688/PRL-85-1012-2000.pdf|archive-date=15 August 2017|url-status=live|hdl-access=free}}</ref><ref>{{Cite journal |last1=Spencer |first1=Joseph A. |last2=Mock |first2=Alyssa L. |last3=Jacobs |first3=Alan G. |last4=Schubert |first4=Mathias |last5=Zhang |first5=Yuhao |last6=Tadjer |first6=Marko J. |date=2022-03-04 |title=A review of band structure and material properties of transparent conducting and semiconducting oxides: Ga2O3, Al2O3, In2O3, ZnO, SnO2, CdO, NiO, CuO, and Sc2O3 |url=https://pubs.aip.org/aip/apr/article-abstract/9/1/011315/2835450/A-review-of-band-structure-and-material-properties |journal=Applied Physics Reviews |volume=9 |issue=1 |pages=011315 |doi=10.1063/5.0078037 |issn=1931-9401}}</ref> Detailed analysis of ZnO and of [[MgO]] show evidence of four and six-fold hydrogen multicentre bonds.<ref>{{cite journal
|last1=Janotti|first1= A.
|title=Hydrogen multicentre bonds|doi=10.1038/nmat1795
|journal=Nature Materials
|volume=6|pages=44–47
|date=2007
|pmid=17143265
|last2=Van De Walle
|first2=C. G.
|issue=1|bibcode = 2007NatMa...6...44J }}</ref>
The doping behavior of hydrogen varies with the material.<ref>{{cite journal|last1=Kilic|first1=C.|title=n-type doping of oxides by hydrogen|doi=10.1063/1.1482783|journal=Applied Physics Letters|volume=81|issue=1|pages=73–75|date=2002|last2=Zunger|first2=Alex|bibcode=2002ApPhL..81...73K|s2cid=96415065}}</ref><ref>{{cite journal
|last1=Peacock| first1=P. W.|doi=10.1063/1.1609245
|title=Behavior of hydrogen in high dielectric constant oxide gate insulators
|journal=Applied Physics Letters
|volume=83
|issue=10
|pages=2025–2027
|date=2003
|last2=Robertson
|first2=J.
|bibcode = 2003ApPhL..83.2025P }}</ref>

=== Niche and evolving uses ===
Other than the uses mentioned above, hydrogen is also used in smaller scales in the following applications:
*Shielding gas: Hydrogen is used as a [[shielding gas]] in [[welding]] methods such as [[atomic hydrogen welding]].<ref>{{cite journal
|last=Durgutlu| first=A.
|title=Experimental investigation of the effect of hydrogen in argon as a shielding gas on TIG welding of austenitic stainless steel
|journal=Materials & Design
|volume=25
|issue=1
|pages=19–23
|date=2003
|doi=10.1016/j.matdes.2003.07.004}}</ref><ref>{{Cite book |last1=Ujah |first1=Chika Oliver |url=https://onlinelibrary.wiley.com/doi/10.1002/9781394331925.ch6 |title=Advanced Welding Technologies |last2=N'Dedji Sodokin |first2=Rodolphe |last3=von Kallon |first3=Daramy Vandi |date=2025-05-05 |publisher=Wiley |isbn=978-1-394-33189-5 |editor-last=Kunar |editor-first=Sandip |edition=1 |pages=107–126 |language=en |chapter=Chapter 6 Atomic Hydrogen Welding |doi=10.1002/9781394331925.ch6 |editor-last2=Mandal |editor-first2=Gurudas}}</ref>

*Coolant: Hydrogen is used as a [[coolant]] in large power stations generators due to its high [[thermal conductivity]] and low density.<ref>{{Cite conference |last1=Kumar |first1=Rajendar |last2=Kumar |first2=Ashwani |date=June 2015 |title=Assessment of impact of hydrogen cooled generator on power system loadability enhancement |url=https://ieeexplore.ieee.org/document/7510166 |conference=2015 International Conference on Energy, Power and Environment: Towards Sustainable Growth (ICEPE) |publisher=IEEE |pages=1–6 |doi=10.1109/EPETSG.2015.7510166 |isbn=978-1-4673-6503-1}}</ref> The first [[hydrogen-cooled turbogenerator]] went into service using gaseous hydrogen as a [[coolant]] in the rotor and the stator in 1937 at [[Dayton, Ohio|Dayton]], Ohio.<ref>{{cite book|url=https://archive.org/stream/chronologicalhis00natirich/chronologicalhis00natirich_djvu.txt|title=A chronological history of electrical development from 600 B.C|author=National Electrical Manufacturers Association|year=1946|page=102|publisher=New York, N.Y., National Electrical Manufacturers Association|access-date=9 February 2016|archive-url=https://web.archive.org/web/20160304141424/http://www.archive.org/stream/chronologicalhis00natirich/chronologicalhis00natirich_djvu.txt|archive-date=4 March 2016|url-status=live}}</ref>

*Cryogenic research: Liquid {{chem2|H2}} is used in [[cryogenic]] research, including [[superconductivity]] studies.<ref>{{cite journal
|last=Hardy
|first=W. N.
|title=From H2 to cryogenic H masers to HiTc superconductors: An unlikely but rewarding path
|journal=Physica C: Superconductivity
|volume=388–389
|pages=1–6
|date=2003
|doi=10.1016/S0921-4534(02)02591-1|bibcode = 2003PhyC..388....1H }}</ref>
*Leak detection: Pure or mixed with nitrogen (sometimes called [[forming gas]]), hydrogen is a [[tracer gas]] for [[Leak detection|detection]] of minute leaks. Applications can be found in the automotive, chemical, power generation, aerospace, and telecommunications industries.<ref>{{cite conference
|first=M.
|last=Block
|title=Hydrogen as Tracer Gas for Leak Detection
|work=16th WCNDT 2004
|publisher=Sensistor Technologies
|date=3 September 2004
|location=Montreal, Canada
|url=http://www.ndt.net/abstract/wcndt2004/523.htm
|access-date=25 March 2008
|archive-url=https://web.archive.org/web/20090108102521/http://www.ndt.net/abstract/wcndt2004/523.htm
|archive-date=8 January 2009
}}</ref> Hydrogen is an authorized food additive (E 949) that allows food package leak testing, as well as having anti-oxidizing properties.<ref>{{cite web
|url=http://ec.europa.eu/food/fs/sfp/addit_flavor/flav15_en.pdf
|title=Report from the Commission on Dietary Food Additive Intake
|publisher=[[European Union]]
|access-date=5 February 2008
|archive-url=https://web.archive.org/web/20080216050325/http://ec.europa.eu/food/fs/sfp/addit_flavor/flav15_en.pdf
|archive-date=16 February 2008
|url-status=live
}}</ref>

*Neutron moderation: [[Deuterium]] (hydrogen-2) is used in [[CANDU reactor|nuclear fission applications]] as a [[neutron moderator|moderator]] to slow [[neutron]]s.
*Nuclear fusion fuel: Deuterium is used in [[nuclear fusion]] reactions.<ref name="nbb" />
*Isotopic labeling: Deuterium compounds have applications in chemistry and biology in studies of [[Kinetic isotope effect|isotope effects]] on reaction rates.<ref>{{cite journal|last1=Reinsch| first1=J.|first2=A. |last2=Katz|first3=J.|last3=Wean|first4=G.|last4=Aprahamian|first5=J. T.|last5=MacFarland
|title=The deuterium isotope effect upon the reaction of fatty acyl-CoA dehydrogenase and butyryl-CoA| journal=J. Biol. Chem.|volume=255
|issue=19|pages=9093–97|date=1980| doi=10.1016/S0021-9258(19)70531-6|pmid=7410413|doi-access=free}}</ref>

*Tritium uses: [[Tritium]] (hydrogen-3), produced in [[nuclear reactor]]s, is used in the production of [[hydrogen bomb]]s,<ref>{{cite journal| last=Bergeron| first=K. D.| title=The Death of no-dual-use| journal=Bulletin of the Atomic Scientists| volume=60| issue=1| pages=15–17| date=2004| url=http://find.galegroup.com/itx/start.do?prodId=SPJ.SP06| doi=10.2968/060001004| access-date=13 April 2008| archive-url=https://web.archive.org/web/20080419051641/http://find.galegroup.com/itx/start.do?prodId=SPJ.SP06| archive-date=19 April 2008| url-status=live| bibcode=2004BuAtS..60a..15B}}</ref> as an isotopic label in the biosciences,<ref name="holte" /> and as a source of [[beta particle|beta radiation]] in [[Tritium radioluminescence|radioluminescent paint]] for instrument dials and emergency signage.<ref name="Traub95" />