Polyaniline (PANI) grafted hierarchical heterostructure nanocomposites for photocatalytic degradation of organic pollutants in waste water: A review

Among the various methods for the removal of toxic organic pollutants from waste water, the photocatalytic degradation by semiconductor photocatalysts has been regarded as an attractive technique because it is environmental friendly, cost effective and easy to execute. However, most of the semiconductor metal oxides/sulfide photocatalysts exhibit high crystallinity and photosensitivity, weak surface-adsorption ability and poor visiblelight response due to which photocatalytic efficiency of those materials were moderately low. The photoexcitation in those materials are quite difficult because of higher band gap energy and requires high energy to excite electrons from the valence band to the conduction band. Conducting polymers like polyaniline (PANI) are used in fabrication of various semiconductor nanoparticles to enhance their photocatalytic efficiency towards photodegradation of toxic organic water pollutants due to its high charge carrying capacity, ability to increases/ decrease the optical band gap energy and transformation of the absorption maxima from the ultraviolet to the visible region. This review paper focuses on the fabrication, characterization and performance enhancement in photodegradation of organic water pollutants in waste water by PANI based heterostructure nanocomposites. Some representative examples are discussed in details along with major challenges and future perspectives.