Sulfonated polyaniline-encapsulated graphene@graphitic carbon nitride nanocomposites for significantly enhanced photocatalytic degradation of phenol: a mechanistic study

The discharge of organic pollutants such as phenols and their derivatives in industrial effluents is a major threat to potable water, leading to a global requirement of cost-effective novel materials for decontamination to get high-quality water. In view of these concerns, sulfonated polyaniline, (s-PANI)@graphitic carbon nitride ( g -C 3 N 4 ) and its nanocomposites with graphene (GN) were synthesized via in situ oxidative polymerization of aniline in the presence of g -C 3 N 4 and GN. The weight ratio of GN varied as 1, 3, and 5% of the weight of g -C 3 N 4 . The resulting s-PANI@ g -C 3 N 4 and s-PANI@ g -C 3 N 4 /GN (1-5%) composites were characterized in terms of structural, optical, morphological, and surface chemical state changes through X-ray diffraction (XRD), UV-visible diffuse absorbance spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The prepared nanocomposites were analyzed for their ability to degrade phenol moieties by high-performance liquid chromatography (HPLC). The results revealed enhanced photocatalytic degradation with GN-based sulfonated s-PANI@ g -C 3 N 4 /GN (1-5%) . The nanocomposite with 1% GN loading showed the highest photocatalytic activity in comparison with nanocomposites containing 3% and 5% GN. The enhancement of photocatalytic activity could be attributed to the involvement of the sp 2 carbon atoms, the interaction of the O&z.dbd;C carbon atoms, and the high migration efficiency of charge carriers. However, higher amounts of GN (3 to 5%) caused a negative shielding effect by impeding charge recombination, thereby resulting in reduced photocatalytic activities of these composites. The proposed methodology can be a potential route for the elimination of phenolic compounds in the treatment of natural water reservoirs. The photocatalytic degradation of phenol through -s-PANI@ g -C 3 N 4 and its nanocomposites with graphene.