Role of graphite oxide (GO) and polyaniline (PANI) in NO2 reduction on GO-PANI composites

Graphite oxide-polyaniline (GO-PANT) composites were obtained by mixing graphite oxide with a polyaniline salt. The extent of surface reduction of the GO and polyanline (emeraldine) was increased by calcination at 350 degrees C. The surface characterization was done using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal analysis, potentiometric titration, elemental analysis, and adsorption of nitrogen at its boiling point. The materials were exposed to NO2 to evaluate their activity for NO2 retention/reduction on the surface. On all samples with the reduced form of polyaniline (emeraldine), a high efficiency for NO2 reduction was observed. This efficiency was governed by the presence of PANT. Moreover, the presence of N-methylformamide solvent in the composite was determined to be an increasing factor for NO retention on the surface-via its hydrogen bonding to the solvent that is interacting with the surface functional groups of graphite oxide. The calcination of GO-PANI at 350 degrees C reduced the GO surface, resulting in a physical mixture of graphite particles and reduced polyaniline (emeraldine). This happened because of the low thermal stability of compounds formed via the reactions of emeraldine with epoxy and carboxylic groups.