Besnard, I.

Guse, B.

Joseph, Y.

Knop-Gericke, A.

Krasteva, N.

Krustev, R.

Rosenberger, M.

Schlögl, R.

Su, D.

Vossmeyer, T.

Wild, U.

Yasuda, A.

MPG.PuRe

• Increase in resitivity with increasing number of cycles• increasing λmax with increasing generation and length of chainComposition and Vapor Sensing Properties of Self-Assembled                     Gold-Nanoparticle/Organic Linker FilmsYvonne Joseph, Nadejda Krasteva, Isabelle Besnard, Berit Guse, Miriam Rosenberger, Ute Wild#, Axel Knop-Gericke#, Dangsheng Su#, Robert Schlögl#, Rumen Krustev§, Akio Yasuda, and Tobias VossmeyerSony International (Europe) GmbH, Materials Science Laboratories, Hedelfinger Str. 61, D-70327 Stuttgart, Germany# Fritz-Haber-Institut der MPG, Department of Inorganic Chemistry, Faradayweg 4-6, D-14195 Berlin, Germany§ Hahn-Meitner Institute Berlin, Glienicker Strasse 100, D-14109 Berlin, GermanyReferencesIntroduction Recent efforts to control the physical and chemical properties of nanostructured materials through a molecular level design have generated enormous interest in thin films comprised of organically linked metal nanoparticles.[1] An interesting application of such metal nanopartice/organic films is their use as chemiresistor-type or microgravimetricgas sensors.[2-4] In these films the nanoparticles provide electric conductivity, ensuring straightforward electrical signal transduction. The organic molecules ensure the mechanical stability of the film, while at the same time providing sites for interactions with vapour molecules. To study the structure and chemical composition of the films we employed AFM, FE-SEM, TEM, and XPS/UPS. The vapour sensitivity of the films at room temperature was investigated by dosing coated chemiresistors and quartz crystal microbalances (QCM) with different solvent vapourswhile monitoring their resistance and resonance frequency, respectively. In addition, the distribution of analytemolecules within the film material was investigated by neutron reflectometry.timeSignaltimeSignaltimeS1S2S3Sensor Array Pattern AnalysisSignalS1 S2 S3Signal PatternSampleDithiolsMetal Nano-particlesElectrode StructureComposite Film= HS-(CH2)N-SHMMMMMMMMMMAromaTimeSignalElectricalresponse[1] A. N. Shipway et al.: Chem. Phys. Chem. 1 (2000) 18[2] J. W. Grate et al.: Anal. Chem. 75 (2003) 1868, and references therein[3] Y. Joseph et al.: J. Phys. Chem. B, (2003) in press, and references therein[4] Y. Joseph et al.: Farad. Disc, (2003) in press, and references therein[5] D. Bethell et al.: J. Electroanal. Chem. 409 (1996) 137Preparation• Wide range of organic materials available• Easy synthesis of starting materials• Automated sensor preparation possibleBy Layer-by-layer self-assembly from solutions of Au-nanoparticles and organic dithiols [5]Well-controlled and reproducible film depositionConclusionThe high sensitivity, the fast response, and the well-controlled chemical selectivity make these materials promising candidates for chemical sensor applications300 400 500 600 700 800 9000.10.20.30.40.50.6-0.05+0.05  AuC16 AuC12 AuC9 AuC6AbsorbanceWavelength [nm]0 5 10 150.00.51.01.5 AuC16 AuC12 AuC9 AuC6 1/R [kΩ-1]Deposition Cycle0 5 10 150.000.020.040.060.08 1/R [kΩ-1]Deposition Cycle• Homogeneous films• Particles size and structure are stable during film assembly• Porous and granular • thin films (19 nm to 34 nm) Microscopy  TEM glueSiO2500 nmAuC12gluefilmSiO220 nm20 nmAuC16 (Flake)SEM40 nmAuPPI-G3AFM.2 µm10 nm010.020.00 nm50  nm100 nm0 10.0 20.0 µmAuC12Sensor d [nm]AuC6 26.2AuC9 27.6AuC12 33.8AuC16 29.9d [nm]19.122.122.323.1SensorAuPPI-G1AuPPI-G2AuPPI-G3AuPPI-G4AuPPI-G5 32.1XPS-Analysis6 9 12 15 1810203040506070C 1sAu 4fS 2pAtomic Ratio [%]Number of  CH 2- Units N• Complete ligand / linker exchange• linker stoichiometry agrees with C/S ratio• ~ 80% of the thiol groups are bound • ~ 300 linker molecules per particleIntensity ratios:90 85020406080290 285152025405 400 3952426283032535 530242628170 165 160151617AuC16S 2pN 1sO 1s  C 1sAu 4fBinding Energy [eV]     Intensity [103counts/s]   .  (C 1s +S2p) /Au 4fC 1s/S 2pS-H/S 2pAu 4f/S-AuAuC6 1.38 3.28 0.20 3.88AuC9 1.66 4.45 0.18 4.03AuC12 2.19 5.83 0.20 3.88AuC16 2.71 7.65 0.24 4.19(C 1s +N 1s) /Au 4fC 1s/(C-N+ C-N+)C-N+) /(C-N+ C-N+)2N-Au/ N1sAuPPI-G4 4.81 1.55 0.20 0.1990 85020406080290 285152025405 4002426283032535 53022242628190 185 18014151617AuPPI-G4Br 3pN 1sO 1s  C 1sAu 4f        Intensity [103counts/s] Binding Energy [eV] Intensity ratios:• linker stoichiometry agrees with C/N ratio• ~ 20% of the nitrogen groups are protonated• ~ 20% of the primary nitrogen groups are bound• ~ 40 linker molecules per particle• Br- and OH- impuritiesVapour Sensitivity • Increase in the resistances• Fast response and fast recovery (t90 < 300 ms for alkylene dithiols)• Tunable selectivity• Selectivity is similar to the solubility properties of the organic molecules• LANGMUIR-type adsorption isotherms• Linear relation between mass uptake and electrical signal 0 1000 2000 3000 4000 5000012345  TCEwaterResponse isothermes of AuPPI-G4 propan-1-oltoluene∆R/Rini [%]vapor concentration [ppm]0 20001234560 2000 2000 200AuPPI-G4, 5000 ppmWaterTCEPropanolToluene∆R/Rini [%]Time [s]    0 50024681012140 50 0 50 0 50AuC16, 5000 ppm∆R/Rini [%]Time [s] WaterTCEPropanolToluene  0 300 600-120-80-4000 300 600 0 300 6000246 ∆fr [Hz]Time [s]  800 ppm∆R/Rini [%]Methanol 2000 ppm 5000 ppm0 50 100-200-10000 50 100 0 50 100051015 ∆f r [Hz]Time [s]  800 ppm∆R/Rini [%] 3000 ppmToluene 8000 ppm0.0 1.0x10-4 2.0x10-40.00.10.20.30.40.50.6. 500 ppm5000 ppm3000 ppm[MeOH] film [mol/dm3 ][MeOH]vapor [mol/dm3]0.0 2.0x10-4 4.0x10-40246400 ppm8600 ppm.[Toluene] film [mol/dm3 ][Toluene]vapor [mol/dm3]0510150 1 2 3 4 50.0 0.1 0.2 0.3∆R/Rini [%]AuPPI-G4AuC16[Toluene]film [mol/dm3][MeOH]film [mol/dm3]-20 -10 0 10 20 30 40 5001x10-62x10-63x10-64x10-65x10-6+ MeOHsat.AuPPI-G4Vapor phaseFilmSubstrateρ(z), Å-2Distance (z) [nm]300 400 500 600 700 800 9000.10.20.30.40.50.6+0.02 each  AuPPI-G5 AuPPI-G4 AuPPI-G3 AuPPI-G2 AuPPI-G1AbsorbanceWavelength [nm]6 8 10 12 14 16555560565570575 λ max [nm]Number of CH2-Units N1 2 3 4 5555560565λ max [nm]Generationetc., typically 14 cyclesAmino-Silane2. Cycle1. CycleSubstrate(electrode structures)Dodecylamine stabilised Au nanoparticles in tolueneDodecylamine stabilised Au nanoparticles in toluene• broad size distribution due to weak stabilisation • fast ligand-exchange reactions2 3 4 5 6 7 8020406080100120140160180  G auss : Pa r tic le  D iam eter  (4 .0  ±  0 .8 ) nmSize [nm]Counts50 nm2 nmAu-CoreNHHLinker solutions in tolueneLinker solutions in tolueneHSSH CN• large variety of  molecules possibleN NNH2H2NH2N NH2N NNNNNH2 NH2NNH2NH2NNNH2NH2NNH2NH2NNNH2NH2NNH2NH2NNNH2NH2NNH2NH2NNNNNH2 NH2NNH2NH2NNNH2NH2NNH2NH2NNNH2NH2NNH2NH2NNNH2NH2NNH2NH2NPPI-G1PPI-G4NanoparticlesSolutionLinkerSolution1 cycleSensorKp.Kbl/mol3.2x104 4.6x103AuC16AuPPI-G4 5.9x103 2.1x104Csatmol/l6.90.40.00 0.01 0.02 0.03 0.04 0.05 0.06 0.0710-510-410-310-210-1100101102103AuPPI-G4 + saturated MeOH  AuPPI-G4ReflectivityQ [Å-1]• Analyte is distributed homogenously in the film and condensed on top of it0 1000 2000 3000 4000 5000024681012  TCEwaterResponse isothermes of AuC16 propan-1-oltoluene∆R/Rini [%]vapor concentration [ppm]0 5 100.00.51.01.5 AuPPI-G1 AuPPI-G2 AuPPI-G3 AuPPI-G4 AuPPI-G5 1/R [kΩ-1]Deposition Cycle0 5 100.000.050.100.150.200.250.30 1/R [kΩ-1]Deposition Cycle

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Composition and vapor sensing properties of self-assembled Gold-nanoparticle/organic linker films

Composition and vapor sensing properties of self-assembled Gold-nanoparticle/organic linker films

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MPG.PuRe

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