Graphene Quantum Dot‐Decorated Polyaniline–ZnO Nanoleaves: Structural and Spectroscopic Characterization and Solar Photocatalytic Degradation of Amido Black and Indigo Carmine

ABSTRACT

This study highlights the potential of GQD–PANI–ZnO hybrid architectures as efficient solar‐responsive materials for environmental remediation applications. Zinc oxide (ZnO), a broadly used n‐type semiconductor, possesses remarkable optoelectronic properties but suffers from poor quantum efficiency and high electron‐hole recombination. To address these limitations, we successfully created a ternary nanohybrid composed of graphene quantum dots (GQDs) and polyaniline (PANI) wrapped ZnO nanoleaves (PZGQD) via a hydrothermal assisted process. The photocatalyst was characterized by XRD, SEM, TEM, BET, and XPS. The composite showed substantially increased surface area relative to pristine ZnO, while XRD indicated extensive amorphous surface coverage of ZnO by the PANI and GQD matrix, consistent with strong interfacial interaction. Based on XPS characterization together with the previously reported optical band‐gap value for the identical PZGQD nanohybrid, a tentative heterojunction‐mediated charge‐transfer pathway is proposed. Photocatalytic activity was evaluated through the degradation of two industrial dyes, amido black and indigo carmine under simulated solar light. The PZGQD composite exhibited superior photocatalytic performance by achieving 82% and 78% degradation of amido black and indigo carmine, respectively, within 120 min. Degradation of amido black followed pseudo‐first‐order kinetics ( k = 0.0125 min ^{− 1} ), while indigo carmine was better described by pseudo‐second‐order kinetics ( k ₂ = 0.027 L mg ⁻¹ , min ^{− 1} , reflecting a fast initial decline followed by a slower decay phase. These findings demonstrate the potential of the PZGQD hybrid as a promising material for dye contaminated wastewater treatment; reusability and long‐term stability were not directly tested in this study and are identified as priorities for follow‐up work.