Multifunctional PANI-LDH nanocomposites: from efficient cango red mineralization to high-yield solar hydrogen generation

Abstract

In this study, a binary nanocomposite comprising polyaniline (PANI) and nickel–aluminum layered double hydroxide (Ni–Al LDH) was synthesized via an oxidative polymerization method, with varying LDH loadings (2, 5, and 7 wt%). Comprehensive physicochemical characterization—including UV–Vis DRS, photoluminescence (PL), XRD, XPS, BET, and EDS—was employed to investigate the optical, structural, compositional, and textural attributes of the materials. From FESEM the porous morphology of PANI and the hierarchical, flower-like morphology of LDH were observed. The photocatalytic performance of the composite was evaluated for Congo red (CR) dye degradation and photocatalytic hydrogen evolution under visible light irradiation. After 120 min, the system achieved 98 % dye removal and approximately 50 % mineralization, as confirmed by total organic carbon analysis. Kinetic studies indicated pseudo-first-order behaviour, with the rate constant exceeding those of pristine PANI, LDH, and TiO₂-P25 by factors of 6, 8, and 9, respectively, evidencing a pronounced synergistic interaction. Operational parameters such as pH, catalyst loading, illumination area, and the presence of scavengers significantly influenced activity. The composite maintained ∼ 70 % catalytic efficiency over six consecutive cycles. HRMS enabled identification of intermediate and final degradation products. Under methanol-assisted conditions, the composite exhibited a hydrogen evolution AQE of 20 %, with AQEs of 18 %, 21 %, and 16 % in acidic, basic, and neutral media, respectively. These results underscore the composite’s bifunctionality for environmental remediation and solar-driven energy conversion.