Morphology transition engineering of WO3 from 1D nanorods to single-crystalline 3D nanocubes grafted with 2D g-C3N4 decorated with 0D SnS2 QDs for pharmaceutical waste photodegradation
J.P. Steffy, Alanoud T. Alfagham, Abdallah M. Elgorban, S. Sudheer Khan
Abstract
The strategic engineering of heterojunction composites offers a transformative pathway to enhance photocatalytic efficiency and address environmental challenges. This study introduces a 3D/2D/0D WO 3 /g-C 3 N 4 /SnS 2 heterojunction photocatalyst for the efficient degradation of ciprofloxacin (CIP), a critical pollutant in water systems. By leveraging a morphological transition from one-dimensional (1D) WO 3 nanorods to 3D nanocubes in the presence of 2D g-C 3 N 4 , and integrating 0D SnS 2 quantum dots , a robust double Z -scheme heterojunction was formed. The tailored WO 3 nanocubes, predominantly exposing (0 2 0) and (2 0 0) planes as confirmed by high-resolution transmission electron microscopy (HRTEM), exhibit a high surface area of 73.48 m 2 /g with a pore radius of 15.532 Å, significantly enhancing photocatalytic activity . The photocatalyst achieved 98.3 % CIP degradation with enhanced rate kinetics of k = 0.0165 min −1 . The reusability tests confirm consistent degradation efficiency across multiple cycles, underscoring its practical viability. Ultraviolet-visible diffuse reflectance spectroscopy (UV–visible-DRS) analysis demonstrates visible light sensitization (bandgap: 2.8 eV), while photoluminescence (PL) studies indicate reduced electron-hole recombination. Comprehensive characterization through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis, and Barrett–Joyner–Halenda (BJH) pore size distribution validates the purity, structure, and surface properties of the composite. Gas chromatography-mass spectroscopy (GC–MS/MS) analysis was used to identify the intermediates formed and a possible degradation pathway was elucidated. Toxicity analysis of intermediates was performed using ecological structure activity relationships (ECOSAR) which confirms the conversion of CIP into less harmful intermediates.