Green Synthesis of Starch-Capped CdS Nanoparticles Doped with Copper (II) and Manganese (II): Structural, Optical, and Photocatalytic Properties

Pure CdS and Cu²⁺/Mn²⁺-doped CdS nanoparticles were synthesized using a green capping method via mechanochemical techniques, with starch as the capping agent. Characterization using XRD revealed a cubic phase structure of CdS nanoparticles, evidenced by peaks at 2θ values of 26.30°, 43.80°, and 51.80° corresponding to the (111), (220), and (311) planes, respectively. SEM-EDAX analysis confirmed the presence of Cd, Cu, Mn, and S elements in the samples. Diffuse reflectance analysis indicated an average crystallite size ranging from 111 nm to 139 nm, accompanied by a band gap energy ranging from 2.25 to 1.95 eV. Raman spectroscopy identified peaks at 366 cm⁻¹, 482 cm⁻¹, and 556 cm⁻¹, attributed to the skeletal modes of the pyranose ring in starch, thus confirming its presence in the starch-capped CdS nanoparticles.