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ZnS is one of the most important semiconducting materials, and this paper discusses the wet chemical synthesis of ZnS nanoparticles in cubic and hexagonal structures. The effect of polyvinyl alcohol concentration on the ZnS particle formation is studied, and ZnS nanocrystals smaller than the Bohr exciton radius have been prepared using the capping...
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... due to the heating of the samples for making powder. The crystallites sizes were found from the Williamson-Hall plot [23] as 1.54, 2.70, 2.34 nm for PZ1, PZ2, and PZ3 samples, respectively, (see Table 1). It is found that the sample made with 0.03 mg/ml PVA possessed smaller crystallites, so this sample was further analyzed by transmission electron microscopy (TEM) by dispersing the samples in ethanol. The TEM, high- resolution TEM (HRTEM), and selected area electron diffraction (SAED) images of the PZ1 sample are shown in Figure 5. It is very clear that the sample consists of nanosized particles, and the interplanar spacing was mea- sured as 0.28 nm for the (111) plane. It was found that it is contracted due to the increased surface area-to-volume ratio when compared to the powder XRD data, and the polycrystalline diffraction rings were labeled to (111), (220), and (311) planes according to the ASTM card no. 77 – 2100 for cubic ZnS. The absorption spectrum of the PZ1sample is shown in Figure 6 with the absorption peak. It is evident from the absorption peak that the interband transitions are happening here due to the strong quantum confinement effect since the crystallite size is smaller than the Bohr exciton radius of ZnS. The band gap of the sample is also calculated using the Brus equation [24] and shown in Table 2 with the crystallite size. It is seen that the band gap calculated from the Brus equation is larger than the band gap obtained from absorption spectra, which shows that the Brus equation cannot be expected to be quantitatively correct for very small particles [25], since the absorption in the case of small particles having a size smaller than the exciton Bohr radius is due to the interband transition. Further, the agglomeration of the nanoparticles also has an effect in their absorption spectra. Further, the PZ1 sample was analyzed by FTIR to find the presence of PVA in the final powder sample. Figure 7 shows the infrared spectrum of pure PVA and PVA-ZnS samples between 500 and 4,000 cm − 1 . The spectrum of PVA seems to be consistent with that previously reported in literatures [26,27]. A relatively broad and intense ν (OH) absorption stretching band is observed at 3,444 and 3,395 cm − 1 , indicating the presence of polymeric association of the free hydroxyl groups and bonded OH stretching vibration. The slight shift of the peaks of the PVA-ZnS sample when comparing to the PVA peaks undoubtedly shows that ZnS is well incorporated in the PVA matrix. The broad O-H absorption stretching vibration is observed at around 3,444 cm − 1 for PVA results from the superposition of multiple polymeric H bonds associated with the crystalline phase and dimeric H bonds associated with the amorphous phase [26]. The absorption bands occurring at 2,901 and 2,917 cm − 1 resulted from anti-symmetric CH stretching and C-H stretching of CH 2 groups, respectively. The bands at 1,733 and 1,626 cm − 1 are due to the C=O stretching and C=C stretching. These carbonyl groups are due to the absorption of the residual acetate groups due to the manufacture of PVA from hydrolysis of polyvinyl acetate [26]. The symmetric bending mode of CH 2 is found at 1,428 cm − 1 . The band at about 1,263 cm − 1 results from the vibration of CH. The band at about 1,045 cm − 1 is assigned to C-O stretching vibration. The IR band posi- tions and their assignments are presented in Table 3. The SEM image of the prepared white powder is shown in Figure 8 with the energy-dispersive X-ray spectroscopy (EDX) data. The SEM image shows that the sample consists of nanosized particles and nanosheets. The elemental ana- lysis shows that the sample possessed Zn, S, and oxygen. So, the sample was studied using its X-ray diffractogram (Figure 9) to confirm the compound and to find the crystal information. Also, the X-ray diffractogram of the sample was compared with the ASTM data of ZnO and ZnS due to the presence of oxygen as seen from EDX. It is found that the obtained the X-ray diffractogram correlates well with the ASTM 39 – 1363 for hexagonal ZnS. The crystals of ZnS were seen aligned along (100), (008), (105), and (110) planes. Further, the peaks for PVA was also seen at 19.72 [28,29] for (101) reflections due to the crystallization of PVA, and other reflection peaks from unknown planes were seen at 2 θ , 11.96, 15.36, 21.16, 24.06, 34.48, 35.45, 40.53, 42.7, 44.6, 45.85, 54.81, and 59.4. Crystal data are shown in Tables 4 and 5, and it is found that the data are well correlated with the hexagonal ZnS. The average crystallite size was calculated using the Williamson-Hall plot [23] as 5.70 nm. The sample was further analyzed by its TEM, HRTEM, and SAED images shown in Figure 10. It is seen that the sample consists of nanosized ZnS particles of about 4.17 nm. The interplanar spacing of the crystals found from the HRTEM is about 0.19 nm, and it may be along the (110) plane. The polycrystalline diffraction rings shown in the SAED images are labeled to the (110), (008), and (105) planes after comparing with the XRD data of the sample. The absorption spectrum of the polycrystalline PC sample is shown in Figure 11, and the band gap of the sample was found at 4.07 eV from the absorption edge (305 nm) which is blueshifted when compared to the bulk value of 3.9 eV. Absorption peaks are not observed in this sample which may be due to the larger crystallite size than the Bohr exciton radius of ZnS. The band gap of the sample with particle and crystallite sizes is shown in Table 6. It is also seen that the band gap found from the Brus equation [24] is larger than the observed band gap from the absorption spectra, and the reason for the difference is already well explained before. The FTIR spectra of the ZnS sample prepared with PVA and trisodium citrate are given in Figure 12 that shows C-H, C-O, and O-H stretching vibrations and C-H bending vibrations. All of the other observed peaks are assigned to their respective values as given in Table 7. The C=C bending vibrations are also seen in the spectra, and that may be due to the presence of esters from the manufacture of PVA. ZnS nanoparticle growth using the concentration of the polymer capping agent polyvinyl alcohol was studied in this paper. ZnS nanocrystals of about 1.54 nm have been prepared, and their optical absorption shows interband transitions. Wurtzite ZnS nanocrystals have been prepared by low-temperature wet chemical method. It is found that the polyvinyl alcohol concentration has a tremendous effect in the particle growth. Particle sizes were varied with the concentration of PVA. The important factor is that the strain was seen negative due to contraction of the particles. The important finding of this experiment is that the preparation of the hexagonal ZnS nanoparticles is possible in lower temperatures when both the trisodium citrate and PVA are used simultaneously with the ZnS precursors. The ...
Citations
... The FTIR spectrum of the prepared ZnS-WDF at room temperature showed peaks at 1456 cm −1 , 1204 cm −1 , and 661 cm −1 ,which can be assigned to ZnS band vibrations corresponding to the sulfide stretching region (Chaliha et al., 2019;Ganguly et al., 2015) (Fig. 1e).The peaks at 2938 cm −1 and 2875 cm −1 can be attributed to CH 2 asymmetrical stretching vibration and symmetrical stretching vibration respectively, while bands at 1033 cm −1 and 1082 cm −1 are assigned to the coupling bands of C-O and C-C stretching vibration modes,while the absorption band at 3375 cm −1 corresponds to stretching vibrations of the O-H bond of trigol and water molecules (Guo et al., 2018). The bands observed at 1649 cm − 1 can be assigned to the C=C stretching mode, while the band at 1409 cm −1 corresponds to CH 2 bending vibrations (Thottoli & Achuthanunni, 2013). ...
Judicial restraints on the use of commercial fungicides for seed treatment have made seed borne cultivations more prone to fungal infestations. Novel and safer alternatives in terms of engineered nanoparticles of essential and ecofriendly nature provide a potential way to combat this problem. In this study, ZnS nanospheres (nZnS) were synthesized in situ as water dispersible formulations (nZnS-WDF), and in vitro studies on rice seed mycopathogens revealed antifungal activity eight fold better than standard fungicide treatment (carbendazim). The antifungal activity is results from topological cellular deformations of treated hyphae,causing cell wall disruption and membrane depolarization, resulting in protein leakage and finally hyphal death. SEM-EDS of treated and disrupted hyphae revealed surface-associated nZnS as the reason for membrane disorganization. In silico binding analysis of nZnS on the active sites of the target enzymes14α-demethylase and 1,3-β-glucan synthase, revealed non hydrogen bonding interactions with enzymes causing enzyme inhibition. Nanopriming of infested rice seeds under controlled conditions with nZnS-WDF at 150 μg/ml significantly reduced the diseased parameters and a noticeable reduction in seed rot (62.59%) and seedling blight (64.02%) were observed in comparison to carbendazim. More importantly, nZnS had an invigorating effect on seeds, boosting the growth of seedlings over a short period. The work presented advocates the use of degradable and eco-safe nZnS for the effective control of seed-borne fungal pathogens necessary for sustainable agriculture. Schematic illustration of synthesis of nZnS-WDF, its in silico, in vitro effects on fungal pathogens and seed treatment studies.
... Table 2 Physical and chemical properties of titanium nanoparticles [9,11] Appearance Black True density g/cm 3 4.506 is an electron microscope that takes a picture of sample surfaces with a packet of high-energy electrons in the form of a scan. The specimens for an SEM testing it is electrically connected from the surface and are electrically charged for not accumulating electrical charges on the surface [12]. ...
In this study, (PVA-PVAC-Ti) nanocomposites have been prepared by using the 'casting method' with different weight percentages of titanium nanoparticles. The (PVA-PVAC-Ti) nanocomposites have been diagnosed by different routes such as the 'Fourier Transform Infrared Spectroscopy (FTIR)', 'scanning electron microscope (SEM)' images, and optical microscope images. The experimental results (FTIR) showed increasing the value of the absorbance of the (PVA-PVAC-Ti) nanocomposites with an increase in the proportion of titanium nanoparticles. All peak characteristics remain the same and the most bond in the same wavenumber. The morphology of the (PVA-PVAC-Ti) nanocomposites films has been studied using (SEM) technique, which showed grain distribution at surface morphology and grain aggregates with increasing of titanium nanoparticles. Photos optical microscope shows the distribution of titanium nanoparticles atoms for all nanocomposite's films, it also shows a continuous network of ions inside the polymers in a ratio (16 wt.%) of (Ti. nanoparticles).
... Table 2 Physical and chemical properties of titanium nanoparticles [9,11] Appearance Black True density g/cm 3 4.506 is an electron microscope that takes a picture of sample surfaces with a packet of high-energy electrons in the form of a scan. The specimens for an SEM testing it is electrically connected from the surface and are electrically charged for not accumulating electrical charges on the surface [12]. ...
In this study, (PVA-PVAC-Ti) nanocomposites have been prepared by using
the 'casting method' with different weight percentages of titanium
nanoparticles. The (PVA-PVAC-Ti) nanocomposites have been diagnosed by
different routes such as the 'Fourier Transform Infrared Spectroscopy (FTIR)',
'scanning electron microscope (SEM)' images, and optical microscope images.
The experimental results (FTIR) showed increasing the value of the absorbance
of the (PVA-PVAC-Ti) nanocomposites with an increase in the proportion of
titanium nanoparticles. All peak characteristics remain the same and the most
bond in the same wavenumber. The morphology of the (PVA-PVAC-Ti)
nanocomposites films has been studied using (SEM) technique, which showed
grain distribution at surface morphology and grain aggregates with increasing of titanium nanoparticles. Photos optical microscope shows the distribution of
titanium nanoparticles atoms for all nanocomposite’s films, it also shows a continuous network of ions inside the polymers in a ratio (16 wt.%) of (Ti. nanoparticles).
... Clearly, with the increase in the thickness of the ZnS layers, the intensity of those two dips increases (Figure 5b). The dips at 1454, 1433 and 1365 cm −1 can be ascribed to the CH or CH2 bending modes [29][30][31]39]. It can be thus concluded that IR analysis provided evidence for the presence of Zn-S-pentanedithiol type MLD hybrid materials, which was already envisaged based on the EDS analysis. ...
... Clearly, with the increase in the thickness of the ZnS layers, the intensity of those two dips increases (Figure 5b). The dips at 1454, 1433 and 1365 cm −1 can be ascribed to the CH or CH 2 bending modes [29][30][31]39]. It can be thus concluded that IR analysis provided evidence for the presence of Zn-S-pentanedithiol type MLD hybrid materials, which was already envisaged based on the EDS analysis. ...
Infrared (IR) spectroscopy is a powerful technique to characterize the chemical structure and dynamics of various types of samples. However, the signal-to-noise-ratio drops rapidly when the sample thickness gets much smaller than penetration depth, which is proportional to wavelength. This poses serious problems in analysis of thin films. In this work, an approach is demonstrated to overcome these problems. It is shown that a standard IR spectroscopy can be successfully employed to study the structure and composition of films as thin as 20 nm, when the layers were grown on porous substrates with a well-developed surface area. In contrast to IR spectra of the films deposited on flat Si substrates, the IR spectra of the same films but deposited on porous ceramic support show distinct bands that enabled reliable chemical analysis. The analysis of Zn-S ultrathin films synthesized by atomic layer deposition (ALD) from diethylzinc (DEZ) and 1,5-pentanedithiol (PDT) as precursors of Zn and S, respectively, served as proof of concept. However, the approach presented in this study can be applied to analysis of any ultrathin film deposited on target substrate and simultaneously on porous support, where the latter sample would be a reference sample dedicated for IR analysis of this film.
... The peaks are observed at 1560 cm À1 , 1078 cm À1 , 524 cm À1 belong to C ¼ C, C-O stretching and C-H bending, respectively. [33] In the FTIR spectrum of ZnS/PVA is shown in Figure 8(b). The band characteristic to 3033 cm À1 and the intensity of this peak decreased drastically. ...
CdxZn1–xS nanoparticles were obtained by sonochemical method and were characterized by X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Ultraviolet-Visible (UV-vis), Fourier-transform infrared Spectroscopy (FTIR). Band gap of CdxZn1–xS nanoparticles were determined in the range of 2.1 eV to 3.4 eV. Lattice structure of nanoparticles are changes from cubic to hexagonal by increasing of x value. At the formation process using three different capping agents (Polyvinyl alcohol (PVA),3-mercaptopropionic acid (MPA) and Styrene). From XRD results, the average sizes of Cd0.4Zn0.6S/PVA,Cd0.4Zn0.6S/Styrene and Cd0.4Zn0.6S/MPA nanoparticles were determined as 7 nm, 9 nm, and 5 nm, respectively. From SEM results, sizes of Cd0.4Zn0.6S/MPA and Cd0.4Zn0.6S/PVA nanoparticles are 10–15 nm and 4–5 nm. From EDX result, the elements ratio in finally formed sample overlaps with the initial ratios. The shift of the absorption band to the low frequency is due to the particle formation in the stabilizer, reduction of energy and the weakening of the vibration movement.
Keywords: CdxZn1–xS nanoparticles, sonochemical synthesis, band gap, structure, capping agents
... Copper composites containing small particles as reinforcement significantly have a higher resistance to wear than pure copper [18]. Also, the distribution of the semiconductor nanoparticles in the field completes the effect of size and increases the bandgap and ultimately leads to an increase in the semiconductor catalytic properties [19]. In addition to proper electrical and thermal conductivity, copper-based composites reinforced with alumina particles have been considered due to high strength caused by the presence of dispersed alumina. ...
Considering the importance of measuring anticancer drugs, a carbon paste electrode (CPE) modified with CuCr2O4/CuO nanofibers in the presence of hydrophobic ionic liquid (IL) was fabricated for methotrexate (MTX) sensing. CuCr2O4/CuO nanofibers were prepared by electrospinning method. Then, the morphology and structure of the nanofibers were studied by scanning electron microscopy, thermal analysis, X-ray diffraction, energy-dispersive X-ray, map analysis, and FT-IR spectroscopy. The electrochemical behavior of MTX at CuCr2O4/CuO/IL/CPE surface was studied using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. After optimization of the experimental parameters, the prepared sensor showed a low detection limit of 25 nM MTX, based on signal-to-noise (S/N = 3), and it can determine in a wide range of 0.1–300 μM in Britton-Robinson buffer solution at pH 2.5. The modified electrode was used to determine MTX concentration in blood and urine samples with good recoveries of 94.1–104.3. This sensor has several advantages such as low cost, easy preparation, high-performance speed and high sensitivity, selectivity, stability, and repeatability.
Scheme of preparation of CuCr2O4/CuO nanofibers by electrospinning method and design of a carbon past electrode using prepared nanofibers (CuCr2O4/CuO/IL/CPE). This electrode was used for methotrexate determination in plasma and urine samples using differential pulse voltammetry.
... In Fig. 3(a), FTIR spectrum of the pure PVA sample clearly reveals the major peaks associated with poly(vinyl alcohol). For example, it can be observed the -OH stretching band at 3377 cm -1 , the stretching C-H from the alkyl group at 2935 cm -1 and the C=O stretching band from acetate group at 1726 cm -1 [17]. According to the Reference [18,19], the vibrational band at about 1090 cm -1 , related to carboxyl stretching band (C-O), is mostly attributed to the crystallinity of the PVA. ...
... For the ZnS:Mn 2+ QDs powder (Fig. 6(c)), the PL peak at about 400 nm (blue emission) is due to defectstates in the ZnS host [32,33] and the other peak at about 588 nm (orange-red emission) is assigned to the Mn 2+ 4 T 1 -6 A 1 emission [17,29]. The blue emission (BE) peak at about 400 nm is attributed to the recombination of electrons in sulfur vacancy (V S ) states with holes in the ground states of ZnS host [32,33] while the orange-red emission (OE) at 588 nm occurs due to spin forbidden 4 T 1 (G) (excited) -6 A 1 (S) (ground) transition within 3d 5 shell of Mn 2+ via energy transfer from the ZnS host to the d electrons of Mn 2+ ions [34][35][36]. ...
... For example, Qi Xiao et al. [13] indicated that the photoluminescence of ZnS:Mn 2+ QDs increased with increasing Mn 2+ concentration and reached its maximum value at the concentration of 1.5% Mn 2+ . C. Zhou et al. [4] observed the maximum photoluminescence intensity of Mn-doped ZnS nanoparticles at a Mn 2+ content of 4% while A. K. Thottoli and co-workers [14] investigated the effect of poly(vinyl alcohol) (PVA) on the ZnS particle formation. Later, R. Viswanath et al. [15] reported that the surface-modified PVA capped Mn 2+ -doped ZnS nanocrystals showed in the multi-color property. ...
... respectively. These crystallite sizes are smaller than the exciton Bohr radius of ZnS (α B~2 .5 nm) [14]. The result indicates that the strong quantum-size effect appears in all the samples. ...
... The vibrational band observed at 2935 cm −1 refers to the stretching C-H from the alkyl group and the peak at about 1726 cm −1 is due to the C˭O stretching from acetate group of PVA. Besides that, the other typical peaks are assigned to the vibrations of groups: C˭C stretching at 1648 cm −1 ; symmetric bending of CH 2 at 1424 cm −1 ; C-H bending at 1256 cm −1 ; C-O stretching 1090 cm −1 ; CH 2 stretching at 843 cm −1 ; and the bending vibration of CH at 606 cm −1 [14]. For PVA-encapsulated ZnS:Mn 2+ QDs, the vibrational band of -OH group also observed at about 3373 cm −1 which indicates the presence of absorbed water molecules on the surface of nanocrystals. ...
... For example, Qi Xiao et al. [13] indicated that the photoluminescence of ZnS:Mn 2+ QDs increased with increasing Mn 2+ concentration and reached its maximum value at the concentration of 1.5% Mn 2+ . C. Zhou et al. [4] observed the maximum photoluminescence intensity of Mn-doped ZnS nanoparticles at a Mn 2+ content of 4% while A. K. Thottoli and co-workers [14] investigated the effect of poly(vinyl alcohol) (PVA) on the ZnS particle formation. Later, R. Viswanath et al. [15] reported that the surface-modified PVA capped Mn 2+ -doped ZnS nanocrystals showed in the multi-color property. ...
... respectively. These crystallite sizes are smaller than the exciton Bohr radius of ZnS (α B~2 .5 nm) [14]. The result indicates that the strong quantum-size effect appears in all the samples. ...
... The vibrational band observed at 2935 cm −1 refers to the stretching C-H from the alkyl group and the peak at about 1726 cm −1 is due to the C˭O stretching from acetate group of PVA. Besides that, the other typical peaks are assigned to the vibrations of groups: C˭C stretching at 1648 cm −1 ; symmetric bending of CH 2 at 1424 cm −1 ; C-H bending at 1256 cm −1 ; C-O stretching 1090 cm −1 ; CH 2 stretching at 843 cm −1 ; and the bending vibration of CH at 606 cm −1 [14]. For PVA-encapsulated ZnS:Mn 2+ QDs, the vibrational band of -OH group also observed at about 3373 cm −1 which indicates the presence of absorbed water molecules on the surface of nanocrystals. ...
... For example, Qi Xiao et al [13] indicated that the photoluminescence of ZnS:Mn 2+ QDs increased with increasing Mn 2+ concentration and reached its maximum value at the concentration of 1.5% Mn 2+ . C. Zhou et al [4] observed the maximum photoluminescence intensity of Mn-doped ZnS nanoparticles at a Mn 2+ content of 4% while A. K. Thottoli and co-workers [14] investigated the effect of poly(vinyl alcohol) (PVA) on the ZnS particle formation. Later, R. Viswanath et al [15] reported that the surface-modified PVA capped Mn 2+ -doped ZnS nanocrystals showed in the multi-color property. ...
... These crystallite sizes are smaller than the exciton Bohr radius of ZnS (α B~2 .5nm) [14]. The result indicates that the strong quantum-size effect appears in all the samples. ...
... The vibrational band observed at 2935 cm -1 refers to the stretching C-H from the alkyl group and the peak at about 1726 cm -1 is due to the C=O stretching from acetate group of PVA. Besides that, the other typical peaks are assigned to the vibrations of groups: C=C stretching at 1648 cm -1 ; symmetric bending of CH 2 at 1424 cm -1 ; C-H bending at 1256 cm -1 ; C-O stretching 1090 cm -1 ; CH 2 stretching at 843 cm -1 ; and the bending vibration of CH at 606 cm -1 [14]. For PVAencapsulated ZnS:Mn 2+ QDs, the vibrational band of -OH group also observed at about 3373 cm -1 which indicates the presence of absorbed water molecules on the surface of nanocrystals. ...
