UV-assisted fabrication of CdS-decorated porous ZnO–PEG disk photocatalysts for efficient dye degradation

• A novel porous ZnO–PEG disk photocatalyst was fabricated via a facile route. • CdS nanoparticles were uniformly deposited by a photochemical UV process. • PEG-assisted porosity enhanced surface area and dye adsorption efficiency. • The CdS/ZnO heterojunction improved charge separation and photocatalytic activity. • The photocatalyst showed 97% MB degradation and high reusability over 5 cycles. In this study, a robust and cost-effective CdS/porous ZnO-PEG disk photocatalyst was successfully fabricated via a PEG-assisted porosity route followed by photochemical deposition of CdS nanoparticles. Polyethylene glycol (PEG) served as an effective pore-forming agent, enhancing the surface area and active site density of ZnO, while CdS nanoparticles were uniformly deposited to form a well-defined ZnO/CdS heterojunction. Structural and morphological analyses using FESEM, EDX, and XRD confirmed the formation of a porous ZnO framework and the successful photodeposition of crystalline CdS nanoparticles. BET analysis showed an increase in specific surface area from 3.17 m 2 g -1 for ZnO to 7.03 m 2 g -1 for CdS/porous ZnO-PEG, with an accompanying increase in mean pore diameter from 5.95 to 7.79 nm. Photocatalytic performance was evaluated via methylene blue (MB) degradation under UV irradiation. The CdS/porous ZnO-PEG disk achieved a degradation efficiency of 80.85% after 30 min under optimal conditions, compared to 30% for bare ZnO and 62.4% for porous ZnO-PEG. The photocatalyst retained approximately 87% of its initial activity after five consecutive cycles, indicating good stability and reusability. These findings suggest that the CdS/porous ZnO-PEG heterostructure is a robust and efficient photocatalyst for potential wastewater purification applications.