Zinc sulfide (ZnS) is one of the first semiconductors discovered. It has traditionally shown remarkable versatility and promise for novel fundamental properties and diverse applications. The nanoscale morphologies of ZnS have been proven to be one of the richest among all inorganic semiconductors. In this article, we provide a comprehensive review of the state-of-the-art research activities related to ZnS nanostructures. We begin with a historical background of ZnS, description of its structure, chemical and electronic properties, and its unique advantages in specific potential applications. This is followed by in-detail discussions on the recent progress in the synthesis, analysis of novel properties and potential applications, with the focus on the critical experiments determining the electrical, chemical and physical parameters of the nanostructures, and the interplay between synthetic conditions and nanoscale morphologies. Finally, we highlight the recent achievements regarding the improvement of ZnS novel properties and finding prospective applications, such as field emitters, field effect transistors (FETs), p-type conductors, catalyzators, UV-light sensors, chemical sensors (including gas sensors), biosensors, and nanogenerators. Overall this review presents a systematic investigation of the ‘synthesis-property-application’ triangle for the diverse ZnS nanostructures.

ZnS nanostructures: From synthesis to applications

Size-tunable nanoparticles (NPs) for pristine cadmium sulfide (CdS) and iron (Fe)-doped (5, 10 and 15%) CdS were synthesized using facile chemical co-precipitation. Size-controlled NPs were prepared with thioglycolic acid (TGA) as the capping agent and their structural, optical, morphological and physiochemical evaluations were performed using X-ray diffraction (XRD), UV–visible spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR). XRD revealed single cubic phase of CdS and later broader peaks upon mixing of Fe, and intensive absorption was recorded in the visible regime upon doping with redshift. FESEM confirmed spherical nanoparticles of Fe–CdS, and Cd–S linkage along with other functional groups was recognized by FTIR. Cd1−xFexS (x = 0, 0.05, 0.10 and 0.15) powder was used as the photocatalyst for methylene blue (MB) degradation in visible light and catalyst in NaBH4’s presence. The control CdS bleached MB faster than doped but doped CdS showed higher catalytic degradation. The Fe-doped CdS NPs showed superior catalytic potential compared to undoped CdS which suggests their use in dye industries, especially leather and tanneries. Additionally, NPs not only show superior catalytic characteristics but also help in cost reduction and complete removal of dyes for wastewater management.

The study of Fe-doped CdS nanoparticle-assisted photocatalytic degradation of organic dye in wastewater

The aim of this study is to clarify the effect of different concentrations of titanium dioxide nanoparticles (Nps) on the properties of two types of heat polymerized acrylic resin. The tested parameters were flexural strength, impact strength, and microhardness. The two types of acrylic resin used in this study were conventional unmodified (Implacryl, Vertex) and high impact heat polymerized acrylic resin (Vertex-Dental, Netherlands). Both types of acrylic resin were modified by using 1% and 5% TiO2 Nps powder. Specimen’s dimensions were prepared according to the American Dental Association Specification No. 12. Three types of specimens were prepared: 1) flexural strength specimens 50 mm × 10 (±0.2) mm × 3 (±0.2) mm, 2) impact strength test specimens 60 mm × 6.0 mm × 4.0 mm, 3) microhardnesss specimens 25 mm × 10 mm × 3 (±0.2) mm. For each test 6 groups were prepared (each group containing 5 samples). Thirty specimens were prepared in each of the three tests, amounting to a total number of 90 specimens. Mechanical properties such as flexural strength (FS), impact strength and microhardness of the above mentioned specimens were determined using universal testing machine, Izod pendulum impact testing machine and Vickers microhardness tester, respectively. ISO Specification No. 1567 was followed in microhardness test. The data was collected and statistically analyzed. Flexural strength considerably decreased by increasing TiO2 concentration in both types of acrylic resin. Impact strength of the conventional acrylic resin modified by 1% of additives significantly increased. The microhardness is significantly increased by addition of 5% of TiO2 Nps. The Incorporation of TiO2 nanoparticles into acrylic resins can adversely affect its flexural strength. Meanwhile, the impact strength can be modified by small percentage of additives (abt. 1%). This effect is directly correlated with the concentration of nanoparticles. On the other hand, concentrations of TiO2 Nps (abt. 5%) positively affect the microhardness of both types of acrylic resin used in the present study.

/pdf/effect-of-titanium-dioxide-nano-particles-incorporation-on-2ha2gntzod.pdf

Effect of Titanium Dioxide Nano Particles Incorporation on Mechanical and Physical Properties on Two Different Types of Acrylic Resin Denture Base

Tandem CdS/TiO2(B) nanosheet photocatalysts for enhanced H2 evolution

In the present work, a chemical co-dispersion technique is employed to develop CdS decorated polyaniline (PANI) nanocomposite. The composite film is used to develop into room temperature ammonia (NH3) sensor. Prior to sensing study, the composite films are characterized to elucidate the structural, morphological and thermal properties. Structural and morphological studies reveal attachment of CdS nanoparticles on polyaniline nanorods. Gas sensing properties of PANI-CdS composite sensor is studied thoroughly and compared with bare PANI sensor. The room temperature gas response towards acetone, ammonia, methanol, formaldehyde and ethanol is investigated and found the sensor to be selective towards ammonia. The maximum gas response of 250 % is achieved with 74 % stability for the composite sensors upon exposure of 100 ppm of NH3 at room temperature. Response and recovery times show a decreasing trend with increasing concentration of NH3 gas.

Room temperature ammonia sensing by CdS nanoparticle decorated polyaniline (PANI) nanorods

We prepared cadmium sulfide (CdS) nanoparticles of a specific size via chemical precipitation at room temperature and characterized them using high-resolution transmission electron microscopy, x-ray powder diffraction, ultraviolet–visible spectroscopy, and Fourier-transform infrared (FTIR) measurements. The results showed that the samples were grown with a cubic phase; the particle size could be changed from 2 nm to 4 nm by varying the molar ratios of the precursors (cadmium chloride and sodium sulfide) in the presence of poly(ethylene glycol) (PEG) as an effective capping agent. The optical bandgap of the synthesized nanoparticles was calculated and ranged from 2.73 eV to 2.92 eV depending on the particle size. A large blue-shift from the bulk bandgap (2.42 eV) was observed owing to the quantum size effect. Surface passivation and adsorption of PEG on the CdS nanoparticles was explained on the basis of FTIR measurements; two bands were observed at 476 cm–1 and 622 cm–1, corresponding to cadmium and sulfide stretching vibrations. We conclude that particle size can be controlled by varying the molar ratios of the precursors. Owing to the PEG encapsulation, the as-prepared samples were extremely stable over time.

Preparation, Characterization, and Size Control of Chemically Synthesized CdS Nanoparticles Capped with Poly(ethylene glycol)

Zinc sulfide nanoparticles with controllable size were synthesized by chemical precipitation. Results from transmission electron microscopy and x-ray powder diffraction showed the samples were grown with the cubic phase. Particle size was varied by varying the molar ratio of zinc chloride to sodium sulfide in the presence of poly(ethylene glycol). The optical band gap was calculated on the basis of ultraviolet–visible spectroscopy and ranged from 4.13 to 4.31 eV depending on particle size. Surface passivation and adsorption of poly (ethylene glycol) on the nanoparticles was explained on the basis of Fourier-transform infrared measurements.

/pdf/synthesis-characterization-and-size-control-of-zinc-sulfide-2l0bue8lpe.pdf

A. R. Lashin

Papers

Preparation, Characterization, and Size Control of Chemically Synthesized CdS Nanoparticles Capped with Poly(ethylene glycol)

Synthesis, Characterization, and Size Control of Zinc Sulfide Nanoparticles Capped by Poly(ethylene glycol)