Cadmium sulfide (CdS) nanoparticles were successfully synthesized by a simple, rapid, and cost-effective aqueous precipitation method carried out at room temperature. In the present work, ammonium hydroxide was employed as a complexing agent to regulate the release of cadmium ions during the reaction, leading to the controlled formation of CdS nanoparticles with improved stability and uniformity. The synthesised nanoparticles were well dispersed in the solution, forming single entities that exhibited excellent resistance to oxidation for several months, which is attributed to the presence of a protective polymer shell surrounding the particles. Structural, morphological, compositional, and optical properties of the synthesized nanoparticles were systematically investigated. X-ray diffraction (XRD) analysis confirmed the formation of phase-pure, crystalline CdS with a hexagonal wurtzite structure, exhibiting characteristic diffraction peaks corresponding to the (100), (111), (110), and (220) planes. Peak broadening indicated nanoscale crystallite dimensions. Scanning electron microscopy (SEM) revealed nearly spherical particles with slight agglomeration due to high surface energy, demonstrating relatively uniform morphology. Energy-dispersive X-ray analysis (EDAX) verified the presence of only Cd and S elements, confirming high purity and stoichiometric composition. Fourier transform infrared (FT-IR) spectroscopy displayed a distinct Cd–S stretching vibration near 641 cm⁻¹, further validating successful compound formation. Optical studies showed a blue-shifted absorption edge around 400 nm compared to bulk CdS, indicating pronounced quantum confinement effects. Photoluminescence (PL) spectra exhibited a strong visible emission peak centered at approximately 490 nm, attributed to band-edge and defect-related recombination. The obtained results demonstrate that the synthesized CdS nanoparticles possess high crystallinity, controlled nanoscale dimensions, and enhanced optical properties, making them promising candidates for optoelectronic, photocatalytic, and sensing applications.

Keywords: CdS; Chemical Precipitation Method; Photoluminescence;