Parameter-Driven Optimization of Displacement Reaction Routes for Controlled ZnS Nanostructure Morphology

The controlled synthesis of zinc sulfide (ZnS) nanostructures remains a critical objective in semiconductor research due to their size-dependent optical, electronic, and catalytic properties. This study presents a systematic investigation of parameter-driven optimization in displacement reaction routes for tailoring ZnS nanostructure morphology. Emphasis is placed on the influence of precursor concentration, reaction temperature, pH, solvent polarity, reaction time, and ionic strength on nucleation kinetics and crystal growth pathways. By carefully modulating these parameters, distinct morphological architectures—including nanoparticles, nanorods, nanosheets, and hierarchical assemblies—were reproducibly obtained without the need for complex templating agents. The results demonstrate that precursor supersaturation governs nucleation density, while temperature and pH critically affect anisotropic growth and defect formation. Solvent environment and reaction duration further influence surface energy minimization and aggregation behavior, enabling fine control over crystallite size distribution and structural uniformity. Structural characterization confirms phase purity and controlled crystallinity, while optical analysis reveals morphology-dependent band gap variation attributed to quantum confinement and surface state modulation. The study establishes clear correlations between reaction parameters and final nanostructure morphology, providing a predictive framework for displacement-reaction-based ZnS synthesis. These findings contribute to scalable fabrication strategies for optoelectronic devices, photocatalysis, and sensing applications where morphology-specific performance is essential.