Fast and selective room-temperature ammonia sensors using silver nanocrystal-functionalized carbon nanotubes.

We report a selective, room-temperature NH(3) gas-sensing platform with enhanced sensitivity, superfast response and recovery, and good stability, using Ag nanocrystal-functionalized multiwalled carbon nanotubes (Ag NC-MWCNTs). Ag NCs were synthesized by a simple mini-arc plasma method and directly assembled on MWCNTs using an electrostatic force-directed assembly process. The nanotubes were assembled onto gold electrodes with both ends in Ohmic contact. The addition of Ag NCs on MWCNTs resulted in dramatically improved sensitivity toward NH(3). Upon exposure to 1% NH(3) at room temperature, Ag NC-MWCNTs showed enhanced sensitivity (~9%), very fast response (~7 s), and full recovery within several minutes in air. Through density functional theory calculations, we found that the fully oxidized Ag surface plays a critical role in the sensor response. Ammonia molecules are adsorbed at Ag hollow sites on the AgO surface with H pointing toward Ag. A net charge transfer from NH(3) to the Ag NC-MWCNTs hybrid leads to the conductance change in the hybrid.

[1]  Wei Li,et al.  Core/shell SmCo5/Sm2O3 magnetic composite nanoparticles , 2012, Journal of Nanoparticle Research.

[2]  Shun Mao,et al.  Ultrafast hydrogen sensing through hybrids of semiconducting single-walled carbon nanotubes and tin oxide nanocrystals. , 2012, Nanoscale.

[3]  L. Ocola,et al.  Ultrafast room temperature NH3 sensing with positively gated reduced graphene oxide field-effect transistors. , 2011, Chemical communications.

[4]  R. Ruoff,et al.  Toward practical gas sensing with highly reduced graphene oxide: a new signal processing method to circumvent run-to-run and device-to-device variations. , 2011, ACS nano.

[5]  Shun Mao,et al.  One-dimensional tungsten oxide growth through a grain-by-grain buildup process , 2010 .

[6]  Junhong Chen,et al.  Room‐Temperature Gas Sensing Based on Electron Transfer between Discrete Tin Oxide Nanocrystals and Multiwalled Carbon Nanotubes , 2009 .

[7]  A. Subrahmanyam,et al.  Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth , 2009 .

[8]  J. Tour,et al.  Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons , 2009, Nature.

[9]  Nicola Marzari,et al.  Sensing mechanisms for carbon nanotube based NH3 gas detection. , 2009, Nano letters.

[10]  M. Weinert,et al.  FLAPW: applications and implementations , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[11]  V. V. Petrov,et al.  Thin sol–gel SiO2–SnOx–AgOy films for low temperature ammonia gas sensor , 2008 .

[12]  J T L Thong,et al.  Improving the NH3 gas sensitivity of ZnO nanowire sensors by reducing the carrier concentration , 2008, Nanotechnology.

[13]  H. Dai,et al.  Chemically Derived, Ultrasmooth Graphene Nanoribbon Semiconductors , 2008, Science.

[14]  J. Brink,et al.  Doping graphene with metal contacts. , 2008, Physical review letters.

[15]  N. Du,et al.  Porous Indium Oxide Nanotubes: Layer‐by‐Layer Assembly on Carbon‐Nanotube Templates and Application for Room‐Temperature NH3 Gas Sensors , 2007 .

[16]  Michele Penza,et al.  Enhancement of sensitivity in gas chemiresistors based on carbon nanotube surface functionalized with noble metal (Au, Pt) nanoclusters , 2007 .

[17]  Patrick Bultinck,et al.  Critical analysis and extension of the Hirshfeld atoms in molecules. , 2007, The Journal of chemical physics.

[18]  Ting Zhang,et al.  Palladium Nanoparticles Decorated Single-Walled Carbon Nanotube Hydrogen Sensor , 2007 .

[19]  Junhong Chen,et al.  A simple and versatile mini-arc plasma source for nanocrystal synthesis , 2007 .

[20]  S. Brahim,et al.  Tailoring Gas Sensing Properties of Carbon Nanotubes , 2007 .

[21]  K. Novoselov,et al.  Detection of individual gas molecules adsorbed on graphene. , 2006, Nature materials.

[22]  Yanqiu Zhu,et al.  Mechanical and NH3 sensing properties of long multi-walled carbon nanotube ropes , 2006 .

[23]  E. Snow,et al.  Role of defects in single-walled carbon nanotube chemical sensors. , 2006, Nano letters.

[24]  A. Berg,et al.  Ammonia sensors and their applications - a review , 2005 .

[25]  U. Diebold,et al.  The surface and materials science of tin oxide , 2005 .

[26]  Chongwu Zhou,et al.  Detection of NO2 down to ppb levels using individual and multiple In2O3 nanowire devices , 2004 .

[27]  Reginald M. Penner,et al.  Amine Vapor Sensing with Silver Mesowires , 2004 .

[28]  M. Fuhrer,et al.  Extraordinary Mobility in Semiconducting Carbon Nanotubes , 2004 .

[29]  M. Lundstrom,et al.  Ballistic carbon nanotube field-effect transistors , 2003, Nature.

[30]  H Brix,et al.  Phosphorus adsorption maximum of sands for use as media in subsurface flow constructed reed beds as measured by the Langmuir isotherm. , 2003, Water research.

[31]  M. Meyyappan,et al.  Carbon Nanotube Sensors for Gas and Organic Vapor Detection , 2003 .

[32]  Joselito M. Razal,et al.  Super-tough carbon-nanotube fibres , 2003, Nature.

[33]  Jijun Zhao,et al.  Gas molecule adsorption in carbon nanotubes and nanotube bundles , 2001, cond-mat/0110375.

[34]  Hongjie Dai,et al.  Functionalized Carbon Nanotubes for Molecular Hydrogen Sensors , 2001 .

[35]  Zettl,et al.  Extreme oxygen sensitivity of electronic properties of carbon nanotubes , 2000, Science.

[36]  Kong,et al.  Nanotube molecular wires as chemical sensors , 2000, Science.

[37]  Thomas Nussbaumer,et al.  Aharonov–Bohm oscillations in carbon nanotubes , 1999, Nature.

[38]  R. Franchy,et al.  TWO CHEMISORBED SPECIES OF O2 ON AG(110) , 1998 .

[39]  C. Lieber,et al.  Atomic structure and electronic properties of single-walled carbon nanotubes , 1998, Nature.

[40]  P.H.B. de Visser,et al.  Risk of damage to crops in the direct neighbourhood of ammonia sources , 1998 .

[41]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[42]  W. D. de Heer,et al.  A Carbon Nanotube Field-Emission Electron Source , 1995, Science.

[43]  S. Iijima.  Helical microtubules of graphitic carbon , 1991, Nature.

[44]  N. Yamazoe.  New approaches for improving semiconductor gas sensors , 1991 .

[45]  F. L. Hirshfeld.  Bonded-atom fragments for describing molecular charge densities , 1977 .