Critical Analysis of Phase Evolution, Morphological Control, Growth Mechanism and Photophysical Applications of ZnS Nanostructures (Zero-Dimensional to Three-Dimensional): A Review

ZnS nanostructures are prominent and promising candidates of class II–IV semiconductor materials that can be prepared by sophisticated techniques. Transition of the material from bulk to nanosize brings forth drastic changes in various properties particularly the photophysical properties. In recent years research has been focused on modifying and manipulating the morphologies of ZnS nanostructures for fabricating photocatalysts, photonic devices, biolabeling agent, optical sensors, detectors, and other novel applications. This review article addresses phase evolution (theoretical modeling approach and experimental validation), morphological control, growth mechanisms based on thermodynamic considerations, surface energy driven models, kinematics, template directed growth, etc., and understanding of the photophysical properties of ZnS based on the dimension of nanostructures (zero-dimensional to three-dimensional). A broad overview is presented for various synthesis techniques from the aspect of different morphologies (peculiar morphologies such as nanosaws, nanospines, nanoswords, nanocircles, cauliflower like structures, etc.) and phase control of the nanostructures followed by discussion of the possible growth mechanism. Some of the novel techniques such as photochemical methods, direct templating routes, and nucleation doping strategies have been included. The structural changes occurring with incorporation of various transition metal ions into the ZnS host and the dependence of fascinating photophysical properties on the different reaction conditions and parameters along with recent advancement in their applications have been introduced in the later sections. The parameters have been discussed and analyzed for tuning the various luminescent properties based on the dimension of the ZnS nanoparticles. We tried to summarize the current status of the research, discuss the issues and concerns in the present scenario, and provide suggestions for further exploration in other potential directions.