In Situ Synthesis of Nanostructured Composites of NiFe Layered Double Hydroxide and Polyaniline for Photocatalytic Degradation of Organic Pollutants and Remediation of Biological Contaminants

The present work discusses on the development of a solid-state mediator Ag-0-based-Z-scheme LDH/PANI/MAA/Ag heterojunction nanocomposite with an intimate morphological contact interface through an electrostatic self-assembly strategy. Here, an Ag-0-decorated layered double hydroxide (LDH) nanosheet-based polymeric nanocomposite has been synthesized by ultrasonic treatment of NiFe LDH with aniline followed by in situ polymerization-stabilization and adsorption-reduction of Ag+ ions at low temperatures. In this synthesis, a mercaptoacetic acid (MAA)-functionalized polyaniline (PANI) promotes the exfoliation of NiFe LDH and stabilizes the nanosheets (LDH) followed by successful adsorption-reduction of Ag+ ions by its chelating groups to Ag-0. The synthesized ternary photocatalyst displayed an enhanced photocatalytic degradation of emerging pollutants (Ciprofloxacin: 97.4%, Reactive Blue 4: 97.7%, and Safranin: 93.1% of degradation) under sunlight irradiation within 80 min. The enhanced photocatalytic performance of the LDH/PANI/MAA/Ag nanocomposite indicates a synergistic effect on electron transfer over components, which is systematically identified by the delayed electron-hole recombination as supported by photoluminescence and electrochemical impedance spectroscopy measurements as well as photostability of the material supported by the chronoamperometry analysis. The synthesized LDH/PANI/MAA/Ag nanocomposite possesses a large specific surface area and an excellent interface between LDH nanosheets, PANI/MAA, and Ag-0, which has been confirmed from the N-2 sorption isotherm, transmission electron microscopy, and high-resolution transmission electron microscopy studies. In addition, the antibacterial potential against Bacillus pumilus (Gram-positive) and Escherichia coli (Gram-negative) bacteria authenticates further advancement of the LDH/PANI/MAA/Ag nanocomposite as a potent material composition.