Flame-Made Pt-Loaded TiO 2

The hydrogen gas sensors were developed successfully using flame-made platinum-loaded titanium dioxide (Pt-loaded TiO2) nanoparticles as the sensing materials. Pt-loaded TiO2 thin films were prepared by spin-coating technique onto Al2O3 substrates interdigitated with Au electrodes. Structural and gas-sensing characteristics were examined by using scanning electron microscopy (SEM) and showed surface morphology of the deposited film. X-ray diffraction (XRD) patterns can be confirmed to be the anatase and rutile phases of TiO2. High-resolution transmission electron microscopy (HRTEM) showed that Pt nanoparticles deposited on larger TiO2 nanoparticles. TiO2 films loaded with Pt nanoparticles were used as conductometric sensors for the detection of H2. The gas sensing of H2 was studied at the operating temperatures of 300, 350, and 400°C in dry air. It was found that 2.00 mol% Pt-loaded TiO2 sensing films showed higher response towards H2 gas than the unloaded film. In addition, the responses of Pt-loaded TiO2 films at all operating temperatures were higher than that of unloaded TiO2 film. The response increased and the response time decreased with increasing of H2 concentrations

Electrochemical Dopamine Biosensor Based on Poly(3-aminobenzylamine) Layer-by-Layer Self-Assembled Multilayer Thin Film

Dopamine (DA) is an important neurotransmitter which indicates the risk of several neurological diseases. The selective determination with low detection limit is necessary for early diagnosis and prevention of neurological diseases associated with abnormal concentration of DA. The purpose of this study is to fabricate a poly(3-aminobenzylamine)/poly(sodium 4-styrenesulfonate) (PABA/PSS) multilayer thin film for use as an electrochemical DA biosensor. The PABA was firstly synthesized using a chemical oxidation method of 3-aminobenzylamine (ABA) monomer with ammonium persulfate (APS) as an oxidant. For electrochemical biosensor, the PABA/PSS thin film was fabricated on fluorine doped tin oxide (FTO)-coated glass substrate using the layer-by-layer (LBL) self-assembly method. The optimized number of bilayers was achieved using SEM and cyclic voltammetry (CV) results. The electroactivity of the optimized LBL thin film toward detection of DA in neutral solution was studied by CV and amperometry. The PABA/PSS thin film showed good sensitivity for DA sensing with sensitivity of 6.922 nA·cm−2·µM−1 and linear range of 0.1–1.0 µM (R2 = 0.9934), with low detection limit of 0.0628 µM, long-term stability and good reproducibility. In addition, the selectivity of the PABA/PSS thin film for detection of DA under the common interferences (i.e., ascorbic acid, uric acid and glucose) was also presented. The prepared PABA/PSS thin film showed the powerful efficiency for future use as DA biosensor in real sample analysis

Nanocomposite Thin Film of Poly(3-aminobenzoic acid) and Multiwalled Carbon Nanotubes Fabricated through an Electrochemical Method

The composite thin films of poly(3-aminobenzoic acid) (PABA) and multiwalled carbon nanotubes (MWNTs) are successfully fabricated through an electrochemical method. The composite mixtures containing 50 mM of 3-aminobenzoic acid with various concentrations of MWNTs (1.0, 2.5, 5.0, 7.5, and 10 mg/mL) in 0.5 M H2SO4 were prepared and used in this study. Cyclic voltammetry (CV) was used for fabrication and monitoring the electropolymerization of the composite thin films with potential range of 0 to 1100 mV for 5 cycles at scan rate of 20 mV/s on indium tin oxide- (ITO)-coated glass substrate. UV-vis absorption spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques were employed to characterize the obtained composite thin films. It was found that MWNTs can enhance the peak current of CV traces of the PABA/MWNTs composite thin films without affecting the UV-vis absorption spectra. The surface morphology of the thin films can be studied using AFM and SEM techniques

In Situ Study of Electropolymerized Poly(3-aminobenzoic acid) Thin Film on BD-R and DVD-R Grating Substrates by Electrochemical-Transmission Surface Plasmon Resonance Spectroscopy

The electropolymerization process and doping/dedoping properties of poly(3-aminobenzoic acid) (PABA) thin films on gold-coated commercial BD-R and DVD-R grating substrates were simultaneously studied by the combination of electrochemical technique and transmission surface plasmon resonance (TSPR) spectroscopy. The optical property as a function of the applied potentials and time dependence during electropolymerization were studied. The obtained TSPR wavelength scan spectra after electropolymerization showed that the maximum wavelength slightly shifted to longer wavelength indicating the increase of film thickness. In addition, the change during construction of PABA-based immunosensor for label-free detection of human immunoglobulin G can be observed

H2 Sensor Based on Au/TiO2 Nanoparticles by Flame-Made

TiO2 is used extensively as a gas sensing material due to its change in electrical conductivity under analyst gas exposure. Gold (Au) is a good catalyst that promotes chemical reactions by reducing the activation energy between sensing film and particular gas. Pure TiO2 and TiO2 nanoparticles doped with 0.25-0.75 at% Au were successfully produced in a single step by Flame spray pyrolysis (FSP) technique. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). TiO2 and Au-doped TiO2 nanoparticle films were prepared by spin-coating technique. The gas sensing of H2 was studied at the operating temperatures ranging from 300-350°C in dry air. It was found that the TiO2 doped with Au sensing film showed higher response of H2, with faster response time (within second) than pure TiO2 sensing film. The response increased and the response time decreased with increasing H2 concentrations