{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,18]],"date-time":"2026-01-18T23:18:02Z","timestamp":1768778282723,"version":"3.49.0"},"reference-count":56,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2019,2,23]],"date-time":"2019-02-23T00:00:00Z","timestamp":1550880000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010661","name":"Horizon 2020 Framework Programme","doi-asserted-by":"publisher","award":["785219"],"award-info":[{"award-number":["785219"]}],"id":[{"id":"10.13039\/100010661","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Estonian Ministry of Education and Science","award":["IUT34-27"],"award-info":[{"award-number":["IUT34-27"]}]},{"name":"Estonian Ministry of Education and Science","award":["IUT2-24"],"award-info":[{"award-number":["IUT2-24"]}]},{"DOI":"10.13039\/501100001729","name":"Swedish Foundation for Strategic Research","doi-asserted-by":"publisher","award":["GMT14-0077"],"award-info":[{"award-number":["GMT14-0077"]}],"id":[{"id":"10.13039\/501100001729","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001729","name":"Swedish Foundation for Strategic Research","doi-asserted-by":"publisher","award":["RMA15-024"],"award-info":[{"award-number":["RMA15-024"]}],"id":[{"id":"10.13039\/501100001729","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Graphene in its pristine form has demonstrated a gas detection ability in an inert carrier gas. For practical use in ambient atmosphere, its sensor properties should be enhanced with functionalisation by defects and dopants, or by decoration with nanophases of metals or\/and metal oxides. Excellent sensor behaviour was found for two types of single layer graphenes: grown by chemical vapour deposition (CVD) and transferred onto oxidized silicon (Si\/SiO2\/CVDG), and the epitaxial graphene grown on SiC (SiC\/EG). Both graphene samples were functionalised using a pulsed laser deposited (PLD) thin V2O5 layer of average thickness \u2248 0.6 nm. According to the Raman spectra, the SiC\/EG has a remarkable resistance against structural damage under the laser deposition conditions. By contrast, the PLD process readily induces defects in CVD graphene. Both sensors showed remarkable and selective sensing of NH3 gas in terms of response amplitude and speed, as well as recovery rate. SiC\/EG showed a response that was an order of magnitude larger as compared to similarly functionalised CVDG sensor (295% vs. 31% for 100 ppm NH3). The adsorption site properties are assigned to deposited V2O5 nanophase, being similar for both sensors, rather than (defect) graphene itself. The substantially larger response of SiC\/EG sensor is probably the result of the smaller initial free charge carrier doping in EG.<\/jats:p>","DOI":"10.3390\/s19040951","type":"journal-article","created":{"date-parts":[[2019,2,25]],"date-time":"2019-02-25T03:06:52Z","timestamp":1551064012000},"page":"951","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Graphene-Based Ammonia Sensors Functionalised with Sub-Monolayer V2O5: A Comparative Study of Chemical Vapour Deposited and Epitaxial Graphene \u2020"],"prefix":"10.3390","volume":"19","author":[{"given":"Margus","family":"Kodu","sequence":"first","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"given":"Artjom","family":"Berholts","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"given":"Tauno","family":"Kahro","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"given":"Jens","family":"Eriksson","sequence":"additional","affiliation":[{"name":"Department of Physics, Chemistry and Biology, Link\u00f6ping University, 58183 Link\u00f6ping, Sweden"}]},{"given":"Rositsa","family":"Yakimova","sequence":"additional","affiliation":[{"name":"Department of Physics, Chemistry and Biology, Link\u00f6ping University, 58183 Link\u00f6ping, Sweden"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3771-7112","authenticated-orcid":false,"given":"Tea","family":"Avarmaa","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"given":"Indrek","family":"Renge","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"given":"Harry","family":"Alles","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3988-6975","authenticated-orcid":false,"given":"Raivo","family":"Jaaniso","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Tartu, W. Ostwald Street 1, EE50411 Tartu, Estonia"}]}],"member":"1968","published-online":{"date-parts":[[2019,2,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"652","DOI":"10.1038\/nmat1967","article-title":"Detection of individual gas molecules adsorbed on graphene","volume":"6","author":"Schedin","year":"2007","journal-title":"Nat. Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"185504","DOI":"10.1088\/0957-4484\/20\/18\/185504","article-title":"Improving gas sensing properties of graphene by introducing dopants and defects: A first-principles study","volume":"20","author":"Zhang","year":"2009","journal-title":"Nanotechnology"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"14198","DOI":"10.1039\/C5CP04422G","article-title":"Defect-engineered graphene chemical sensors with ultrahigh sensitivity","volume":"18","author":"Lee","year":"2016","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.physb.2013.11.009","article-title":"Adjusting the electronic properties and gas reactivity of epitaxial graphene by thin surface metallization","volume":"439","author":"Eriksson","year":"2014","journal-title":"Phys. B Condens. Matter"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"84082","DOI":"10.1039\/C6RA16863A","article-title":"High efficiency room temperature detection of NO2 gas based on ultrathin metal\/graphene devices","volume":"6","author":"Zhao","year":"2016","journal-title":"RSC Adv."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"113108","DOI":"10.1063\/1.4962959","article-title":"Highly sensitive NO2 sensors by pulsed laser deposition on graphene","volume":"109","author":"Kodu","year":"2016","journal-title":"Appl. Phys. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"22185","DOI":"10.1039\/c3ra43480j","article-title":"A UV light enhanced TiO2\/graphene device for oxygen sensing at room temperature","volume":"3","author":"Zhang","year":"2013","journal-title":"RSC Adv."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.matdes.2018.04.087","article-title":"Performance tuning of gas sensors based on epitaxial graphene on silicon carbide","volume":"153","author":"Rodner","year":"2018","journal-title":"Mater. Design"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1993","DOI":"10.1557\/jmr.2016.242","article-title":"Effects of the fabrication temperature and oxygen flux on the properties and nitrogen dioxide sensitivity of the tin oxides-tin\/graphene hybrid sensor","volume":"31","author":"Mu","year":"2016","journal-title":"J. Mater. Res."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Eason, R. (2006). Pulsed Laser Deposition of Thin Films: Applications-Led Growth of Functional Materials, Wiley-Interscience (Online Service).","DOI":"10.1002\/0470052120"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"053119","DOI":"10.1063\/1.4742327","article-title":"Sub-ppt gas detection with pristine graphene","volume":"101","author":"Chen","year":"2012","journal-title":"Appl. Phys. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1054","DOI":"10.1016\/j.snb.2016.05.114","article-title":"Graphene based sensor for environmental monitoring of NO2","volume":"236","author":"Novikov","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1145","DOI":"10.4028\/www.scientific.net\/MSF.858.1145","article-title":"Modified epitaxial graphene on SiC for extremely sensitive and selective gas sensors","volume":"858","author":"Eriksson","year":"2016","journal-title":"Mater. Sci. Forum"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"094704","DOI":"10.1063\/1.4793709","article-title":"Elementary steps of the catalytic NOx reduction with NH3: Cluster studies on reactant adsorption at vanadium oxide substrate","volume":"138","author":"Gruber","year":"2013","journal-title":"J. Chem. Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"571","DOI":"10.3762\/bjnano.8.61","article-title":"Graphene functionalised by laser-ablated V2O5 for a highly sensitive NH3 sensor","volume":"8","author":"Kodu","year":"2017","journal-title":"Beilstein J. Nanotechnol."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Jaaniso, R., and Tan, O.K. (2013). Semiconductor Gas Sensors, Woodhead Publ.","DOI":"10.1533\/9780857098665"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Kodu, M., Berholts, A., Kahro, T., Eriksson, J., Yakimova, R., Avarmaa, T., Renge, I., Alles, H., and Jaaniso, R. (2018). Highly sensitive NH3 sensors using CVD and epitaxial graphene functionalised with vanadium(V) oxide: A comparative study. Proceedings, 2.","DOI":"10.3390\/proceedings2130854"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"565","DOI":"10.4028\/www.scientific.net\/MSF.645-648.565","article-title":"Analysis of the formation conditions for large area epitaxial graphene on SiC substrates","volume":"645\u2013648","author":"Yakimova","year":"2010","journal-title":"Mater. Sci. Forum"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"162111","DOI":"10.1063\/1.4899276","article-title":"Photo-activated oxygen sensitivity of graphene at room temperature","volume":"105","author":"Berholts","year":"2014","journal-title":"Appl. Phys. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Yazdi, G.R., Iakimov, T., and Yakimova, R. (2016). Epitaxial graphene on SiC: A review of growth and characterization. Crystals, 6.","DOI":"10.3390\/cryst6050053"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1103\/PhysRevLett.97.187401","article-title":"Raman spectrum of graphene and graphene layers","volume":"97","author":"Ferrari","year":"2006","journal-title":"Phys. Rev. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1038\/nnano.2013.46","article-title":"Raman spectroscopy as a versatile tool for studying the properties of graphene","volume":"8","author":"Ferrari","year":"2013","journal-title":"Nat. Nanotechnol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4320","DOI":"10.1021\/nl802156w","article-title":"Raman spectra of epitaxial graphene on SiC and of epitaxial graphene transferred to SiO2","volume":"8","author":"Lee","year":"2008","journal-title":"Nano Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1016\/j.carbon.2017.02.026","article-title":"Multi-scale investigation of interface properties, stacking order and decoupling of few layer graphene on C-face 4H-SiC","volume":"116","author":"Bouhafs","year":"2017","journal-title":"Carbon"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"201918","DOI":"10.1063\/1.2929746","article-title":"Raman spectra of epitaxial graphene on SiC (0001)","volume":"92","author":"Hundhausen","year":"2008","journal-title":"Appl. Phys. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"964","DOI":"10.1021\/nl802852p","article-title":"Raman topography and strain uniformity of large-area epitaxial graphene","volume":"9","author":"Robinson","year":"2009","journal-title":"Nano Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1038\/nnano.2008.67","article-title":"Monitoring dopants by Raman scattering in an electrochemically top-gated graphene transistor","volume":"3","author":"Das","year":"2008","journal-title":"Nat. Nanotechnol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1021\/nl2031629","article-title":"Doping monolayer graphene with single atom substitutions","volume":"12","author":"Wang","year":"2012","journal-title":"Nano Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"14095","DOI":"10.1103\/PhysRevB.61.14095","article-title":"Interpretation of Raman spectra of disordered and amorphous carbon","volume":"61","author":"Ferrari","year":"2000","journal-title":"Phys. Rev. B"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3190","DOI":"10.1021\/nl201432g","article-title":"Quantifying defects in graphene via Raman spectroscopy at different excitation energies","volume":"11","author":"Jorio","year":"2011","journal-title":"Nano Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4944","DOI":"10.1021\/nl1029607","article-title":"Atmospheric oxygen binding and hole doping in deformed graphene on a SiO2 substrate","volume":"10","author":"Ryu","year":"2010","journal-title":"Nano Lett."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1727","DOI":"10.1016\/j.carbon.2011.12.008","article-title":"The influence of atmosphere on electrical transport in graphene","volume":"50","author":"Yang","year":"2012","journal-title":"Carbon"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1103\/PhysRevLett.99.126805","article-title":"Electronic structure of epitaxial graphene layers on SiC: Effect of the substrate","volume":"99","author":"Varchon","year":"2007","journal-title":"Phys. Rev. Lett."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1038\/nmat2382","article-title":"Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide","volume":"8","author":"Emtsev","year":"2009","journal-title":"Nat. Mater."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1006","DOI":"10.1016\/j.snb.2013.09.068","article-title":"Temperature induced inversion of oxygen response in CVD graphene on SiO2","volume":"190","author":"Jaaniso","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"462","DOI":"10.1016\/j.apcatb.2009.09.005","article-title":"Adsorption and oxidation of NH3 over V2O5\/AC surface","volume":"92","author":"Sun","year":"2009","journal-title":"Appl. Catal. B Environ."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/S0926-3373(00)00214-9","article-title":"NO\u2013NH3 coadsorption on vanadia\/titania catalysts: Determination of the reduction degree of vanadium","volume":"29","author":"Centeno","year":"2001","journal-title":"Appl. Catal. B Environ."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1016\/j.snb.2015.02.089","article-title":"Pulsed laser deposited nanostructured vanadium oxide thin films characterized as ammonia sensors","volume":"217","author":"Huotari","year":"2015","journal-title":"Sens. Actuators B Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"355701","DOI":"10.1088\/0957-4484\/22\/35\/355701","article-title":"Molecular absorption and photodesorption in pristine and functionalized large-area graphene layers","volume":"22","author":"Lin","year":"2011","journal-title":"Nanotechnology"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1016\/j.snb.2010.12.046","article-title":"Epitaxially grown graphene based gas sensors for ultra sensitive NO2 detection","volume":"155","author":"Pearce","year":"2011","journal-title":"Sens. Actuators B Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1088\/2053-1583\/3\/1\/015006","article-title":"Atmospheric doping effects in epitaxial graphene: Correlation of local and global electrical studies","volume":"3","author":"Panchal","year":"2016","journal-title":"2D Materials"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/j.carbon.2016.03.018","article-title":"Effects of humidity on the electronic properties of graphene prepared by chemical vapour deposition","volume":"103","author":"Melios","year":"2016","journal-title":"Carbon"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"244701","DOI":"10.1063\/1.4849556","article-title":"Elementary steps of the catalytic NOx reduction with NH3: Cluster studies on reaction paths and energetics at vanadium oxide substrate","volume":"139","author":"Gruber","year":"2013","journal-title":"J. Chem. Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"4701","DOI":"10.1021\/jp990363p","article-title":"NH3 adsorption on the Br\u00f6nsted and Lewis acid sites of V2O5 (010): A periodic density functional study","volume":"103","author":"Yin","year":"1999","journal-title":"J. Phys. Chem. B"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"5983","DOI":"10.1021\/ie0308487","article-title":"Adsorption behavior of moisture over a vanadia\/titania catalyst: A study for the selective catalytic reduction process","volume":"43","author":"Lin","year":"2004","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_46","unstructured":"Lide, D.R. (2008). CRC Handbook of Chemistry and Physics, CRC Press. [89th ed.]."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"103107","DOI":"10.1063\/1.4795292","article-title":"Self healing of defected graphene","volume":"102","author":"Chen","year":"2013","journal-title":"Appl. Phys. Lett."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"3936","DOI":"10.1021\/nl300985q","article-title":"Graphene reknits its holes","volume":"12","author":"Zan","year":"2012","journal-title":"Nano. Lett."},{"key":"ref_49","first-page":"1","article-title":"Mechanism of the defect formation in supported graphene by energetic heavy ion irradiation: The substrate effect","volume":"5","author":"Li","year":"2015","journal-title":"Sci. Rep."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"285703","DOI":"10.1088\/0957-4484\/23\/28\/285703","article-title":"Effect of SiO2 substrate on the irradiation-assisted manipulation of supported graphene: A molecular dynamics study","volume":"23","author":"Zhao","year":"2012","journal-title":"Nanotechnology"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"385502","DOI":"10.1088\/0957-4484\/22\/38\/385502","article-title":"Adsorption of gas molecules on transition metal embedded graphene: A search for high-performance graphene-based catalysts and gas sensors","volume":"22","author":"Zhou","year":"2011","journal-title":"Nanotechnology"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1038\/nnano.2009.474","article-title":"Towards a quantum resistance standard based on epitaxial graphene","volume":"5","author":"Tzalenchuk","year":"2010","journal-title":"Nat. Nanotechnol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"241607","DOI":"10.1063\/1.4729556","article-title":"The influence of substrate morphology on thickness uniformity and unintentional doping of epitaxial graphene on SiC","volume":"100","author":"Eriksson","year":"2012","journal-title":"Appl. Phys. Lett."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1007\/s00604-018-2750-5","article-title":"A review on chemiresistive room temperature gas sensors based on metal oxide nanostructures, graphene and 2D transition metal dichalcogenides","volume":"185","author":"Joshi","year":"2018","journal-title":"Microchim. Acta"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"1702168","DOI":"10.1002\/adfm.201702168","article-title":"Two-dimensional nanostructured materials for gas sensing","volume":"27","author":"Liu","year":"2017","journal-title":"Adv. Funct. Mater."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"795","DOI":"10.1002\/adma.201503825","article-title":"Nanostructured materials for room-temperature gas sensors","volume":"28","author":"Zhang","year":"2016","journal-title":"Adv. Mater."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/4\/951\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:34:20Z","timestamp":1760186060000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/4\/951"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,2,23]]},"references-count":56,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2019,2]]}},"alternative-id":["s19040951"],"URL":"https:\/\/doi.org\/10.3390\/s19040951","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,2,23]]}}}