The preparing of polyaniline- silver composites by oxidation in comparison with polyaniline –carbon nanotube composites prepared by electro-oxidation for hydrogen sensors

Abstract

The first series preparation of polyaniline (PANI) - silver composites by the oxidation of aniline with silver nitrate in the 0.2 and 1 mol L-1 M aqueous solutions of acetic acid, the reaction condition produce a composite that have a conductivity of about 4000 S cm-1 at 72 wt. % (20 vol%) of silver (Ag). Scanning Electron Microscope (SEM) illustrates the formation of nanostructured Ag (nanowires) coated with polyaniline. In the second series, the preparation of polyaniline - multiwall Carbon nanotubes(MWCNTs) composites were included MWCNTs of 0.25wt %, 0.5wt % or 1wt % added to 0.1 M distilled aniline under reflex procedure with 0.3M H2S04 (pH 4) investigated by cyclic voltammetry. A cyclic potential ranged from -100 mV to 1500 mV (scan rate of 30mV S-1) at room temperature for fabricating PANI/MWCNTs composite. Images of SEM showed that the PANI/MWCNTs Nanofieber structure with diameters has the range of 50nm-70 nm. Results of current-voltage (I-V) curves showed increase in electrical conductivity with increasing proportion of MWCNTs. PANI-silver composite which has been prepared in 1 mol L-1 of acetic acid and PANI-1wt% MWCNTs composite as hydrogen sensor, the results have showed that PANI-MWCNTs sensor have more sensitivity compared to PANI-silver sensor.)