Enhanced photocatalytic performance of PANI-rGO-MnO₂ ternary composite for degradation of organic contaminants under visible light

This work examines the potential of conducting polymers with transition metal oxides as a photocatalyst in environmental remediation. A visible light-responsive ternary composite of PANI-rGO-MnO₂ was synthesized and evaluated its photocatalytic activity of a cationic dye (i.e., methylene blue, MB) in an aqueous solution. The surface morphologies and structural properties of the synthesized PANI, PANI-rGO, and PANI-rGO-MnO₂ were examined. In the case of ternary composite, the successful growth/incorporation of MnO₂ nanoparticles into the PANI-rGO composite was demonstrated. Furthermore, the lowered optical band gap of the ternary composite illustrates the extended light absorption range for the PANI-rGO-MnO₂ photocatalyst. The photocatalytic experiments show that the PANI-rGO-MnO₂ ternary composite exhibited significantly enhanced catalytic and photocatalytic activity for 90% degradation of methylene blue (MB) under visible light irradiation within 2 h. It could be attributed to synergistic effects by (i) facilitating the electron transfer from excited by reduced graphene oxide from the excited dye to PANI-MnO₂ and (ii) reducing the recombination of photogenerated electron/hole pairs originating from the heterostructure of the ternary composite. The present work provides new insights into the synthesis of conducting polymer PANI, PANI-rGO, and the ternary composite of PANI-rGO-MnO₂ as an efficient photocatalyst, and the developed composites would have potential applications in environmental remediation related fields.