Kinetic and Thermodynamic Control in the Displacement Synthesis of Zinc Sulfide (ZnS) Nanomaterials

The controlled synthesis of zinc sulfide (ZnS) nanomaterials through displacement reactions has attracted sustained interest due to the material’s tunable optical band gap, high exciton binding energy, and broad applicability in optoelectronic and photocatalytic systems. However, the phase purity, crystallite size, morphology, and defect structure of ZnS are strongly governed by the interplay between kinetic and thermodynamic factors during nucleation and growth. This study examines the role of kinetic and thermodynamic control in the displacement synthesis of ZnS nanomaterials, emphasizing how precursor reactivity, temperature, supersaturation, solvent environment, and reaction time influence phase evolution and structural stability. Under kinetically controlled conditions characterized by rapid nucleation and limited diffusion, metastable phases and smaller crystallites are preferentially formed. In contrast, thermodynamically controlled regimes, achieved through elevated temperatures and extended reaction durations, favor phase transformation toward energetically stable structures with improved crystallinity and reduced defect density. By systematically modulating reaction parameters, the transition between cubic (zinc blende) and hexagonal (wurtzite) ZnS phases can be directed, enabling tailored optical and electronic properties. The findings highlight the importance of balancing reaction rate and energy minimization pathways to achieve reproducible and application-specific ZnS nanostructures. This work provides a conceptual and practical framework for rational design of ZnS nanomaterials via displacement synthesis, contributing to improved control over structure–property relationships in semiconductor nanochemistry.