{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T07:08:29Z","timestamp":1771484909631,"version":"3.50.1"},"reference-count":26,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2012,6,8]],"date-time":"2012-06-08T00:00:00Z","timestamp":1339113600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Polypyrrole\/single wall carbon nanotube composites were synthesized by in-situ chemical polymerization using pyrrole (PPy) as precursor and single wall carbon nanotubes (SWNTs) as additive component. Electron microscope images reveal that SWNTs component acts as nucleation sites for PPy growth in the form of spherical and cylindrical core-shell structures. The SWNTs\/PPy core-shell results in thin n-p junctions which modify the PPy bandgap and reduce the work function of electrons. As a result of the strong coupling, Raman and IR spectra show that the PPy undergoes a transition from polaron to bipolaron state, i.e., indicating an increase in the conductivity. In the UV-Vis spectra, the 340 nm adsorption band (\u03c0*-\u03c0 transition) exhibits a red shift, while the 460 nm adsorption band (bipolaron transition) experiences a blue shift indicating a change in electronic structure and a relocation of polaron levels in the band gap of PPy. The modification in PPy electronic structure brings in a synergistic effect in sensing feature. Upon exposure to oxygen (an oxidizing agent) and NH3 gas (a reducing agent), the PPy\/SWNTs nanocomposite shows an enhancement in sensitivity exceeding ten folds in comparison with those of PPy or SWNTs.<\/jats:p>","DOI":"10.3390\/s120607965","type":"journal-article","created":{"date-parts":[[2012,6,8]],"date-time":"2012-06-08T11:25:11Z","timestamp":1339154711000},"page":"7965-7974","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":84,"title":["Synergistic Effects in the Gas Sensitivity of Polypyrrole\/Single Wall Carbon Nanotube Composites"],"prefix":"10.3390","volume":"12","author":[{"given":"Duong Ngoc","family":"Huyen","sequence":"first","affiliation":[{"name":"School of Engineering Physics, Hanoi University of Science and Technology, No.1, Daicoviet, Hanoi 10000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nguyen Trong","family":"Tung","sequence":"additional","affiliation":[{"name":"School of Engineering Physics, Hanoi University of Science and Technology, No.1, Daicoviet, Hanoi 10000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tran Dinh","family":"Vinh","sequence":"additional","affiliation":[{"name":"School of Engineering Physics, Hanoi University of Science and Technology, No.1, Daicoviet, Hanoi 10000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nguyen Duc","family":"Thien","sequence":"additional","affiliation":[{"name":"School of Engineering Physics, Hanoi University of Science and Technology, No.1, Daicoviet, Hanoi 10000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2012,6,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Skotheim, T.A., and Reynolds, J.R. (2007). Handbook of Conducting Polymer, CRC Press. [3rd ed.].","DOI":"10.1201\/b12346"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2537","DOI":"10.1021\/cr9801014","article-title":"Conjugated polymer-based chemical sensors","volume":"100","author":"McQuade","year":"2000","journal-title":"Chem. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1038\/nmat768","article-title":"Conducting polymers in electronic chemical sensors","volume":"2","author":"Jiri","year":"2003","journal-title":"Nat. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"267","DOI":"10.3390\/s7030267","article-title":"Review: Gas sensors based on conducting polymers","volume":"7","author":"Bai","year":"2007","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1080\/10408340290765489","article-title":"Chemical gas sensors based on organic semiconductor polypyrrole","volume":"32","author":"Karin","year":"2002","journal-title":"Crit. Rev. Anal. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Ram, M.K., and Bhethanabotla, V.R. (2010). Sensors for Chemical and Biological Applications, CRC Press.","DOI":"10.1201\/9780849333668"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"768","DOI":"10.1016\/j.snb.2005.07.022","article-title":"Gas and humidity response of iron oxide-Polypyrrole nanocomposites","volume":"114","author":"Tandon","year":"2006","journal-title":"Sens. Actuators B"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.synthmet.2005.03.021","article-title":"NO2 gas sensing based on ordered ultrathin films of conducting polymer and its nanocomposite","volume":"151","author":"Ram","year":"2005","journal-title":"Synth. Met."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1708","DOI":"10.1016\/j.synthmet.2010.06.005","article-title":"Gas sensitivity study of polypyrrole\/WO3 hybrid materials to H2S","volume":"160","author":"Geng","year":"2010","journal-title":"Synth. Met."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/S0040-6090(01)00837-9","article-title":"Electrical and NOx gas sensing properties of metallo-phthalo-cyanine-doped polypyrrole\/silicon heterojunctions","volume":"392","year":"2001","journal-title":"Thin Solid Films"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1016\/j.snb.2010.11.009","article-title":"Fabrication of polypyrrole-phenylalanine nano-films with NH3 gas sensitivity","volume":"153","author":"Ihm","year":"2011","journal-title":"Sens. Actuators B"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1753","DOI":"10.1351\/pac200274091753","article-title":"Sensors and sensor arrays based on conjugated polymers and carbon nanotubes","volume":"74","author":"Dai","year":"2002","journal-title":"Pure Appl. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"59","DOI":"10.2174\/187221007779814826","article-title":"Fabrication and application of polymer composites comprising carbon nanotubes","volume":"1","author":"Mylvaganam","year":"2007","journal-title":"Recent Pat. Nanotechnol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1038\/318162a0","article-title":"C60: Buckminsterfullerene","volume":"318","author":"Kroto","year":"1985","journal-title":"Nature"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1038\/354056a0","article-title":"Helical microtubules of graphitic carbon","volume":"354","author":"Ijima","year":"1991","journal-title":"Nature"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3838","DOI":"10.1021\/ja010172b","article-title":"Noncovalent sidewall functionalization of single-walled carbon nanotubes for protein immobilization","volume":"123","author":"Chen","year":"2001","journal-title":"J. Am. Chem. Soc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1491","DOI":"10.1021\/cr030070z","article-title":"About supramolecular assemblies of \u03c0-conjugated systems","volume":"105","author":"Hoeben","year":"2005","journal-title":"Chem. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Wang, Y., and Yeow, J.T.W. (2009). Review article: A review of carbon nanotubes-based gas sensors. J. Sens.","DOI":"10.1155\/2009\/493904"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1016\/j.carbon.2006.09.011","article-title":"Gas sensitivity of a composite of multiwalled carbon nanotubes and polypyrrole prepared by vapor phase polymerization","volume":"45","author":"Chen","year":"2007","journal-title":"Carbon"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1005","DOI":"10.1002\/adma.200306176","article-title":"Enhanced sensitivity of a gas sensor incorporating single-walled carbon nanocomposites","volume":"16","author":"An","year":"2004","journal-title":"Adv. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"500","DOI":"10.1016\/j.snb.2009.04.061","article-title":"Thin film polypyrrole\/SWCNTs nanocomposites based NH3 sensor operated at room temperature","volume":"140","author":"Hieu","year":"2009","journal-title":"Sens. Actuators B"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"961","DOI":"10.3724\/SP.J.1077.2011.00961","article-title":"Polypyrrole coated carbon nanotubes: Preparation, characterization, and gas-sensing properties","volume":"26","author":"Wang","year":"2011","journal-title":"J. Inorg. Mater."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"6141","DOI":"10.1016\/j.electacta.2007.03.070","article-title":"Study of polaron and bipolaron states in polypyrrole by in situ Raman spectroelectrochemistry","volume":"52","author":"Santos","year":"2007","journal-title":"Electrochim. Acta"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1063\/1.1768304","article-title":"Work functions of individual single-walled carbon nanotubes","volume":"85","author":"Suzuki","year":"2004","journal-title":"Appl. Phys. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3636","DOI":"10.1063\/1.332406","article-title":"Polypyrrole\u2010semiconductor Schottky barriers","volume":"54","author":"Skotheim","year":"1983","journal-title":"J. Appl. Phys."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"10533","DOI":"10.1021\/ja042998u","article-title":"Sensitivity of ammonia interaction with single-walled carbon nanotube bundles to the presence of defect sites and functionalities","volume":"127","author":"Feng","year":"2005","journal-title":"J. Am. Chem. 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