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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.

Silver nanowire arrays with high aspect ratios have been prepared using potentiostatic electrodeposition within the confined nanochannels of a commercial porous anodic aluminium oxide template. The nucleation and growth processes are intensively studied by current versus time transients. Scanning electron microscopy results show that the nanowires have a highly anisotropic structure with diameters and lengths of 170 nm and 58 µm, respectively, which coincide with the dimensions of the template used. Structural characterization using x-ray diffraction shows that the Ag nanowires are highly crystalline, and those obtained at higher overpotentials present a very strong [220] preferred crystallographic orientation. The optical properties of the silver nanowires embedded in the alumina template show a clear edge close to 320 nm, that is an expected value for a silver–alumina composite material.