Sunlight-Driven Degradation of Antibiotics and Dyes Using Polyaniline/Layered Double Hydroxide Nanosheet/Co(OH)2 Nanosheet Z-Scheme Photocatalytic Nanocomposite for Wastewater Treatment

Abstract

Recent progress in simple, one-step, room-temperature synthesis for developing polymer-mediated heterojunction photocatalysts demonstrates great potential for harnessing solar energy to sustainably eliminate pollutants and pathogens from wastewater. This work represents the synthesis of a conducting polymer integrated mixed exfoliated layered nanocomposite, polyaniline/NiAl LDH/Co(OH)₂ (i.e., PANI/LDH/CH) via an in situ one-step approach, combining polymerization and exfoliation at ambient temperature. During the synthesis process, NiAl LDH [LDH] and [CH] were formed in situ and exfoliated using polyaniline (PANI), leading to the formation of a PANI-mediated Z-scheme heterojunction. The nanocomposite exhibits excellent photocatalytic activity, achieving degrading efficiencies of 97% for ciprofloxacin (CFX), 98% for norfloxacin (NFX), 96% for methyl orange (MO), and 96% for safranin (SFN) within 90 min under visible light irradiation. The improved performance is attributed to enhanced PANI-exfoliated layer interfacial contact, which promotes efficient charge separation, exciton mobility, suppressed electron–hole recombination, and high photostability as evidenced by photoluminescence (PL), time-resolved PL, and electrochemical impedance spectroscopy (EIS). Chronoamperometry measurements further support the photostability of the material. Structural characterization via N₂ adsorption isotherms and transmission electron microscopy revealed a high surface area and strong interfacial interaction among LDH, CH, and PANI. Additionally, the nanocomposite demonstrates strong antibacterial activity against Bacillus pumilus (Gram-positive) and Escherichia coli (Gram-negative), highlighting its potential toward environmental remediation.