In this paper, we are showing that the reduced graphene oxide could be used as a sensing layer in a chemoresitive gas sensors. The results of the investigation during which the sensing structure was affected by hydrogen and nitrogen dioxide in nitrogen and synthetic air in various temperatures are presented. We have observed that in certain temperature range, the resistance of the sensing structure was increased when hydrogen was in the gas mixture and was decreased when nitrogen dioxide was in the mixture, compared to the state without both gases. Moreover, we are showing that the humidity has no influence for the resistance of structure during the measurements with hydrogen. The measurements of the resistance has also been supplemented by the images of the structure obtained using scanning electron microscopy.
In this paper, we present the results of the measurements obtained using atomic force microscopy (AFM). The subject of research were the reduced graphene oxides which were obtained by oxidation (in first step) of the graphites and thermally reduction (in the second step). The three types of graphites (flake, scale and synthetic) and three different method of oxidation were used in the measurements. The special attention was paid to the height and horizontal sizes of the obtained material. The results was analysed and relevant conclusions were drawn from them.
Three precursors of graphite were employed to synthesise graphite oxides (GrO) that are now routinely obtained by the oxidation of a precursor graphite. These oxidation samples exhibit highly broadened D and G Raman bands which caused by the large amount of defects of graphene sheets. In addition, chemical oxidation results in the multiple peaks such as G*, D+D` and 2D`(in place of the conventional 2D band), which are activated by defects. The broad G band might also be deconvoluted in the actual G band and D` band, thereby attributing the broadening in G band. The band position and intensity ratio have also been demonstrated in the oxidized graphite.