Facile synthesis and characterization of Al-doped ZnS: Synergistic effect of doping and d-glucose capping agent on Photodegradation of malachite green

In this study, pristine and aluminum-doped zinc sulfide nanoparticles were synthesized via the facile chemical co-precipitation method in an aqueous medium, in the absence and presence of d-glucose as the capping agent. The structural, morphological, optical, and photocatalytic properties of the synthesized samples were investigated. X-ray diffraction (XRD) analysis confirmed the formation of cubic ZnS, while 1 and 2% Al-doped samples exhibited identical diffraction patterns, indicating successful incorporation of Al3+ ions into the ZnS crystal lattice. FESEM and TEM images revealed nearly spherical nanoparticles. Diffuse reflectance spectroscopy (DRS) spectra showed a red shift in the absorption edge upon Al doping, and the optical band gap estimated from Tauc plots decreased from 3.81 to 3.60 eV with increasing dopant concentration. Electrochemical impedance spectroscopy (EIS) results demonstrated that Al-doping significantly enhanced the transfer of charge carriers at the electrode-electrolyte interface. The photocatalytic performance of the samples was evaluated through the degradation of malachite green under xenon lamp irradiation. Among the samples, 2% Al-doped ZnS synthesized in the presence of d-glucose (ZA2-G) exhibited superior photocatalytic performance, achieving 98.7% dye removal. The pH variation showed that the best dye removal efficiency was achieved at the inherent pH of the malachite green solution. Furthermore, ZA2-G demonstrated good stability and reusability, indicating its potential for practical photocatalytic applications. Radical trapping experiments revealed that •OH radicals play a dominant role in the photodegradation mechanism of malachite green.