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Graphene films and ribbons were grown on Ni-coated Si substrates using the microwave plasma enhanced chemical vapor deposition method. We report the structure, morphology, and quality of graphene films and ribbons. The semiconducting nature of the CVD-grown graphene was observed by studying resistance−temperature variation in the range 25 to 200 °C, using the four-point probe method. Graphene exhibited an increase of resistance upon exposure of CO and a decrease in resistance upon pure O2 and NO2 exposures. It was observed that graphene films show sensor signal ∼3 and 35 for 100 ppm of CO and 100 ppm of NO2 whereas the graphene ribbons show the sensor signal values of 1.5 and 18 for 100 ppm of CO and 100 ppm of NO2. The gas sensor mechanism was observed to be mainly dependent on the charge carrier transfer on conducting graphene surfaces caused by the adsorption of gases.

We present the room temperature detection of carbon monoxide using Au decorated zinc oxide (ZnO) nanowires. Zinc oxide nanowires were grown via the vapor liquid solid method whereas the gold nanoparticles were prepared by the solution growth method. The surface of the ZnO nanowires was decorated by Au nanoparticles. Gas sensing properties of such nanowires were studied at room temperature for various concentrations of CO (100 to 1000 ppm) in synthetic air. Enhancement in gas sensing response by Au decoration on ZnO nanowires was observed. Au nanoparticles act as a catalyst in chemical sensitization and improve the reaction and response time. The improvement in gas sensing behavior is attributed to the change in conductivity of the metal decorated ZnO nanowires on CO exposure due to the transfer of electrons resulting from gas oxidation at the ZnO nanowire surface.

Functional and composite nanodiamonds (NDs) are rapidly emerging as promising materials for the next generation for quantum information processing, electronic material, magnetotometry, novel imaging, and IR fluorescence applications, etc. Nanocomposites of ND particles with conductive polymers [i.e., polyaniline (PANI)] displayed novel properties resulting from the molecular level interaction of diamond with PANI molecules. We have synthesized for the first time the ND-PANI nanocomposites by oxidative polymerization of aniline using ammonium peroxydisulfate [(NH4)2S2O8)] under controlled conditions. The ND-PANI nanocomposite films were characterized by UV−vis, FTIR, electrochemistry, impedance, scanning electron microscope, transmission electron microscope, and electrical conductivity techniques. Current−voltage characteristics of ND-PANI nanocomposite show the ohmic junction. The electrochemical investigation on ND-PANI revealed the wider potential values with independent redox characteristics of PANI and ND. There is an interaction of the free electron pairs of the nitrogen atoms of the PANI with a charged molecule on the surface of ND with PANI. The concept of using an active electronic barrier ND-PANI barrier built-in electric field is created at the metal surface. The ND-PANI takes advantage of the excellent corrosion inhibitor characteristics of steel and aluminum due to its chain conformation and electronic properties, as demonstrated in this work.

Recently, polymer matrix-based nanocomposites have become a prominent area of research and development in optics, as well as in optoelectronic, biomedical, electrical and electronic applications. Organic polymer-based electronic devices have the potential to be lower in cost and more flexible in the manner in which they are manufactured. However, they need significant improvement in both efficiency and long-term stability. Therefore, we made an attempt to synthesize zinc oxide (ZnO)-polyaniline (PANI) using chemical and emulsion polymerization techniques. The properties of ZnO-PANI films were then systematically characterized with several physical techniques. Electrochemical investigations revealed that the individual redox properties of ZnO and PANI can be maintained in a nanocomposite ZnO-PANI system. Furthermore, our results indicated that ZnO-PANI films can exhibit a wide redox potential window. Moreover, we observed the formation of a single-layer nano-Schottky junction in ZnO-PANI films, and interesting positive temperature coefficient properties in ZnO-PANI-embedded polystyrene films. Polymer Journal ( INTRODUCTIONIn recent years, there has been considerable interest among researchers to develop novel inorganic _ organic hybrid materials with compositions modulated on the nanoscale because of their many potential applications in display technologies, microelectronics, catalysis, sensors and molecular electronics. 1 The fabrication of nanocomposite films by wet chemical techniques has been proven to be a more simple and inexpensive strategy than technologically demanding physical methods. 2 Recently, Ram et al. [3][4][5][6][7][8] developed metal oxide and conducting polymer nanocomposite films of TiO 2 -PANI, TiO 2 -polypyrrole, SnO 2 -polyhexylthiophene, TiO 2 -poly (thiopheneaniline) nanocomposite, Mn-Ferrite-PANI and MWCNT-poly (o-anisidine) using wet chemical methods and used them extensively in gas sensing and molecular electronics applications. PANI is one of the most widely studied materials because of its unique electrochemical, chemical and physical properties. In addition, PANI exhibits high electrical conductivity and good environmental stability in both doped and pristine (undoped) states. 9-11 The electronic, optical, photo-electrochemical, photoconductive, photovoltaic, thermal and sensing, for example, gas sensing and biosensing, properties of PANI could be improved by incorporating PANI with polystyrene latex, multiwalled carbon nanotubes, single-walled nanotubes, montmorillonite, graphite, MCM-41, TiO 2 and SnO 2 micro and nanoparticles. 9-18 PANI composites have also been shown to possess a variety of unique mechanical, electrical and structural properties because of synergistic effect from intimate mixing

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The graphene (G)-polythiophene (PTh) nanocomposite was synthesized by a chemical oxidative polymerization technique and characterized using Field Emission Scanning Electron Microscopy (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM), Raman Spectroscopy, Fourier transform Infrared spectroscopy (FTIR), X-ray-diffraction (XRD), Electrochemical Impedance spectroscopy(EIS) and cyclic voltammetry (CV) techniques. The electrochemical properties of G-PTh nanocomposite supercapacitor electrodes were investigated in different electrolytes solutions and a specific discharge capacitance of 154 F/g was estimated from different charge/discharge current cycles. Our proposed research is transformative as the G-conducting polymer based electrode material with unique and excellent properties, such as, high conductivity, wider tunable potential window, high stability of the electrode material in doped form, faster charge transfer rate, and short charging times, that allows the fabrication of high performance supercapacitors for practical applications.