Synthesis of monodisperse zinc sulfide particles grafted with concentrated polystyrene brush by surface-initiated nitroxide-mediated polymerization

Monodisperse zinc sulfide (ZnS) particles of diameters ranging from 120 to 400 nm were prepared and then coated with a thin layer of silica (SiO₂). After the surface modification with an alkoxyamine derivative, polystyrene (PS) brushes of chain lengths ranging from 30,000 to 114,000 in M_n with relatively low polydispersities less than 1.5 in M_w/M_n were successfully grafted by surface-initiated nitroxide-mediated polymerization, where the M_n and M_w are the number- and weight-averaged molecular weights, respectively. The graft density reached a value as high as 0.9 chains nm⁻². These core-shell hybrid particles (ZnS@SiO₂-PS) were highly dispersible, without any aggregation, in various solvents good for PS, also forming a monolayer at the air-water interface by spreading its solution. The transmission electron microscopic observation of the monolayers deposited on a solid support revealed two-dimensionally close-packed arrays of particles. These monolayers exhibited a beautiful structural color dependent on the angle of incident light because of such an ordered array of the ZnS cores with a high refractive index. Hollow spheres constituted of a SiO₂ shell with well-defined, high-density PS brushes were first synthesized by selective dissolution of the ZnS core from the ZnS@SiO₂-PS hybrid particle.     

Photoinduced electron transfer and interfacial photocatalysis behaviour of ZnS/CdS binary co-colloid system

The interfacial photoinduced electron transfer and related secondary photochemical behaviour in the system of ZnS/CdS co-colloid superfine particles were studied by means of ESR and fluorescence spectroscopy techniques. The photoinduced charge-separation and the radical intermediates produced in the secondary redox reactions initiated via charge separation, as well as the mechanism of reaction processes, were investigated in detail through simultaneous excitation of two colloid components or only one of them. Research results indicated that, as E_(g(ZnS))>E_λ>E_(g(CdS)), only CdS in co-colloid system might be excited. The transfer process of electron from the conduction band of CdS to the conduction band of ZnS is forbidden, and under the excitation wavelength range used, the electron transfer of cocolloid system was impossible, thus the photo redox reactions of the substrate in co-colloid system had no obvious difference from those reactions happening in single colloid system. While the excitation wav     

Preparation and phase relationships in systems of the type CdSMIMIIIS2 where MI = Ag,Cu and MIII = Al,Ga, In

Systems of the type M^IM^IIIS₂ (chalcopyrite)-CdS (wurtzite) where M^I = Ag, Cu and M^III = Al, Ga, In were investigated to determine the regions of mutual solid solubility. It was found that the chalcopyrite structure could not tolerate extensive CdS substitution. When M^III was Al or Ga the solubility of M^IM^IIIS₂ in CdS was also very limited. However, when M^III = In (r_In³⁺ ? r_Ga³⁺ > r_Al³⁺), the solubility of M^IInS₂ in CdS was quite extensive (～50%). These results are consistent with a prior study on systems of the type M^IM^IIIS₂ZnS which indicated that in sulfides, larger cations tend to result in the formation of new quaternary, wurtzite phases.     

Dendronized Cellulose Nanocrystals as Templates for Preparation of ZnS and CdS Quantum Dots

Cellulose nanocrystals (CNC) isolated from bleached bagasse pulp were modified with a second-generation isocyanate dendron (G2-dendron) to prepare dendronized cellulose nanocrystals (DCN). Transmission electron microscopy (TEM), elemental analysis for nitrogen, Fourier transform infrared (FTIR) and ¹³C magic angle spinning nuclear magnetic resonance (¹³C MAS NMR) proved occurrence of the modification of cellulose nanocrystals surfaces. The dendronized cellulose nanocrystals were used as templates for formation of ZnS and CdS quantum dots with uniform diameter at low temperature in water. The prepared DCN/QDs were highly soluble in water. TEM images showed that the size of the prepared quantum dots was about 5 nm in diameter. UV-Visible and fluorescence spectroscopy showed absorption and emission at wavelength values lower than that reported for bulk ZnS and CdS.     

One‐pot Synthesis of CdS Nanocrystals Hybridized with Single‐Layer Transition‐Metal Dichalcogenide Nanosheets for Efficient Photocatalytic Hydrogen Evolution

Exploration of low‐cost and earth‐abundant photocatalysts for highly efficient solar photocatalytic water splitting is of great importance. Although transition‐metal dichalcogenides (TMDs) showed outstanding performance as co‐catalysts for the hydrogen evolution reaction (HER), designing TMD‐hybridized photocatalysts with abundant active sites for the HER still remains challenge. Here, a facile one‐pot wet‐chemical method is developed to prepare MS₂–CdS (M=W or Mo) nanohybrids. Surprisedly, in the obtained nanohybrids, single‐layer MS₂ nanosheets with lateral size of 4–10 nm selectively grow on the Cd‐rich (0001) surface of wurtzite CdS nanocrystals. These MS₂–CdS nanohybrids possess a large number of edge sites in the MS₂ layers, which are active sites for the HER. The photocatalytic performances of WS₂–CdS and MoS₂–CdS nanohybrids towards the HER under visible light irradiation (>420 nm) are about 16 and 12 times that of pure CdS, respectively. Importantly, the MS₂–CdS nanohybrids showed enhanced stability after a long‐time test (16 h), and 70 % of catalytic activity still remained.     

Self-assembly of a mesoporous ZnS/mediating interface/CdS heterostructure with enhanced visible-light hydrogen-production activity and excellent stability

We designed and successfully fabricated a ZnS/CdS 3D mesoporous heterostructure with a mediating Zn_1–xCd_xS interface that serves as a charge carrier transport channel for the first time. The H₂-production rate and the stability of the heterostructure involving two sulfides were dramatically and simultaneously improved by the careful modification of the interface state via a simple post-annealing method. The sample prepared with the optimal parameters exhibited an excellent H₂-production rate of 106.5 mmol h^–1 g^–1 under visible light, which was 152 and 966 times higher than CdS prepared using ethylenediamine and deionized water as the solvent, respectively. This excellent H₂-production rate corresponded to the highest value among the CdS-based photocatalysts. Moreover, this heterostructure showed excellent photocatalytic stability over 60 h.     

Reverse micelle-derived Cu-doped Zn1−xCdxS quantum dots and their core/shell structure

Reverse micelle chemistry-derived Cu-doped Zn_1?xCd_xS quantum dots (QDs) with the composition (x) of 0, 0.5, 1 are reported. The Cu emission was found to be dependent on the host composition of QDs. While a dim green/orange emission was observed from ZnS:Cu QDs, a relatively strong red emission could be obtained from CdS:Cu and Zn_0.5Cd_0.5S:Cu QDs. Luminescent properties of undoped QDs versus Cu-doped ones and quantum yields of alloyed ZnCdS versus CdS QDs are compared and discussed. To enhance Cu-related red emission of CdS:Cu and Zn_0.5Cd_0.5S:Cu core QDs, core/shell structured QDs with a wider band gap of ZnS shell are also demonstrated.     

CdS Nanocubes Adorned by Graphitic C3N4 Nanoparticles for Hydrogenating Nitroaromatics: A Route of Visible-Light-Induced Heterogeneous Hollow Structural Photocatalysis

Modulating the transport route of photogenerated carriers on hollow cadmium sulfide without changing its intrinsic structure remains fascinating and challenging. In this work, a series of well-defined heterogeneous hollow structural materials consisting of CdS hollow nanocubes (CdS NCs) and graphitic C₃N₄ nanoparticles (CN NPs) were strategically designed and fabricated according to an electrostatic interaction approach. It was found that such CN NPs/CdS NCs still retained the hollow structure after CN NP adorning and demonstrated versatile and remarkably boosted photoreduction performance. Specifically, under visible light irradiation (λ ≥ 420 nm), the hydrogenation ratio over 2CN NPs/CdS NCs (the mass ratio of CN NPs to CdS NCs is controlled to be 2%) toward nitrobenzene, p-nitroaniline, p-nitrotoluene, p-nitrophenol, and p-nitrochlorobenzene can be increased to 100%, 99.9%, 83.2%, 93.6%, and 98.2%, respectively. In addition, based on the results of photoelectrochemical performances, the 2CN NPs/CdS NCs reach a 0.46% applied bias photo-to-current efficiency, indicating that the combination with CN NPs can indeed improve the migration and motion behavior of photogenerated carriers, besides ameliorating the photocorrosion and prolonging the lifetime of CdS NCs.     

Synthesis of CdS, ZnS and Ag2S nanoparticles stabilized by sodium bis(2-ethylhexyl)sulfosuccinate and polyoxyethylenesorbitan monooleate in aqueous medium

The effect of synthesis conditions (molar ratio between precursors, concentration of surfactants, synthesis temperature) on the size of CdS, ZnS and Ag₂S nanoparticles (NPs) stabilized by sodium bis(2-ethylhexyl)succinate and polyoxyethylenesorbitan monooleate was studied. It was established that stabilization by polyoxyethylenesorbitan results in formation of smaller NPs (～8 nm) as compared to that in the presence of sodium bis(2-ethylhexyl)sulfosuccinate (14–60 nm), which is due to the difference between the adsorption rates of these surfactants onto the surface of synthesized NPs. The resulting aqueous dispersions of CdS, ZnS and Ag₂S NPs exhibit long-term stability to sedimentation. The nanoparticle size increases insignificantly with temperature increasing to 65–70°C and rises abruptly at higher temperatures. The increase in the ratio between concentrations of precursors (sulfide and metal ions) also results in an increase in NP size, allowing one to synthesize nanoparticles of prescribed sizes. The optical properties of the resulting nanoparticles were studied. The positions of the exciton peaks and the luminescence intensity peaks of the dispersions of synthesized CdS and ZnS NPs were determined.     

Surfactant-ligand co-assisted solvothermal technique for the synthesis of different-shaped CdS nanorod-based materials

1-D nanorods, twinrods, golfclubs, and tripods of CdS were prepared via a surfactant-ligand co-assisted solvothermal method at 160°C. The surfactant of S-dodecylisothiounium bromide (C₁₂) used in the process was favorable for synthesis of different-shaped CdS nanorod with high aspect ratio. X-ray diffraction (XRD) and TEM images showed that the 1-D nanorods had wurtzite phase and others had a zinc blende core and wurtzite arms. The morphologies of CdS prepared under different conditions suggested the “template-assistance” of the surfactant and that the nonaqueous organic media are important for the self-assembling of inorganic components at atomic level.     

One-pot synthesis of CuInS2 and CuInS2/MS (M=Cd,Zn) core–shell luminescent nanocrystals: a low-temperature and low-cost approach

The single-pot synthesis of highly crystalline and fluorescent chalcopyrite CuInS₂ (CIS) colloidal nanoparticles has been reported by thermal decomposition of metal ethyl xanthate (at ~110 °C) for the first time. The fluorescence emission wavelength can also be readily tuned from the UV to the visible region by merely prolonging the reaction time, as the PL emission may be varied from 550 to 675 nm. The synthesized CIS is subjected to postdeposition treatment with CdS/ZnS in one pot route using cadmium/zinc xanthate at low temperature (~80 °C) to improve the quantum yield of core–shell (CIS/CdS or ZnS) nanocrystallites as compared to CIS core. The stability of core–shell particularly CIS/ZnS system upon continuous laser exposure suggests the formation of surface bonds with superior mechanical stability. This low-cost synthesis of such nontoxic QDs using green chemical routes is a promising approach for the fabrication of optoelectronic and biosensing devices. Graphical Abstract

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水溶性的CdSe/CdS/ZnS量子点的合成及表征

用L-半胱氨酸盐(Cys)作为稳定剂,合成了水溶性的双壳结构的CdSe/CdS/ZnS半导体量子点。吸收光谱和荧光光谱结果表明,双壳结构的CdSe/CdS/ZnS纳米微粒比单一的CdSe核纳米粒子和单核壳结构的CdSe/CdS纳米粒子具有更优异的发光特性。用透射电子显微镜(TEM)、ED、XRD、XPS和FTIR等方法对CdSe核和双壳层的CdSe/CdS/ZnS纳米微粒的结构、分散性及形貌分别进行了表征。     

Synthesis of ZnS Nanospheres in Microemulsion Containing Cationic Gemini Surfactant

The reverse microemulsion containing cationic gemini surfactant trimethylene‐1,3‐bis(dodecyldimethyl ammonium bromide) (12‐3‐12, 2Br^?) is applied to synthesize ZnS nanospheres. Narrow size distributed ZnS nanospheres with controllable size and uniform morphology are successfully fabricated by direct reaction of ZnCl₂ and Na₂S in the reverse microemulsion systems. Except for the appearance of large aggregates owing to quantum size effects when the incubation time is 2 h, with increasing the incubation time from 12 to 48 h, the diameter of the ZnS nanosphere can be controlled as 20–25 nm and 140 nm, respectively. X‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐visible absorption spectroscopy are applied to characterize the resulting ZnS nanoparticles. In the system used in the present study uniform nanosphere morphology can be synthesized, with the incubation time as an important factor in controlling the size of as‐prepared products.     

Highly-controllable imprinted polymer nanoshell at the surface of silica nanoparticles based room-temperature phosphorescence probe for detection of 2,4-dichlorophenol

This paper reports a facile and general method for preparing an imprinted polymer thin shell with Mn-doped ZnS quantum dots (QDs) at the surface of silica nanoparticles by stepwise precipitation polymerization to form the highly-controllable core–shell nanoparticles (MIPs@SiO₂–ZnS:Mn QDs) and sensitively recognize the target 2,4-dichlorophenol (2,4-DCP). Acrylamide (AM) and ethyl glycol dimethacrylate (EGDMA) were used as the functional monomer and the cross-linker, respectively. The MIPs@SiO₂–ZnS:Mn QDs had a controllable shell thickness and a high density of effective recognition sites, and the thickness of uniform core–shell 2,4-DCP-imprinted nanoparticles was controlled by the total amounts of monomers. The MIPs@SiO₂–ZnS:Mn QDs with a shell thickness of 45 nm exhibited the largest quenching efficiency to 2,4-DCP by using the spectrofluorometer. After the experimental conditions were optimized, a linear relationship was obtained covering the linear range of 1.0–84 μmol L⁻¹ with a correlation coefficient of 0.9981 and the detection limit (3σ/k) was 0.15 μmol L⁻¹. The feasibility of the developed method was successfully evaluated through the determination of 2,4-DCP in real samples. This study provides a general strategy to fabricate highly-controllable core–shell imprinted polymer-contained QDs with highly selective recognition ability.     

Non-quantum-confinement optics in (CdS)n clusters

Geometry optimizations and the calculation of properties of (CdS)_n clusters for n = 2–12 are performed using density functional theory (DFT) with generalized gradient approximation. The all-electron basis is used for sulfur atoms while cadmium atoms are treated using relativistic effective core potentials. It is confirmed that the lowest energy state of (CdS)_n has a ring structure for n = 3–5 and a cage geometry for n ? 6. Optical absorption spectra are simulated using the energies and oscillator strengths of the first 20 singlet–singlet transitions computed for each cluster by time-dependent DFT. It is found that the energies of the lowest optical transitions do oscillate around the bulk gap value, which contradicts the concept of quantum confinement. The congender (CdSe)₁₂ and (CdTe)₁₂ clusters are found to show similar optical properties as the (CdS)₁₂ cluster.     

Triton-X mediated interconnected nanowalls network of cadmium sulfide thin films via chemical bath deposition and their photoelectrochemical performance

Thin films of cadmium sulfide (CdS) have been wet chemically deposited onto fluorine-doped tin oxide (FTO) coated conducting glass substrates by using non-ionic surfactant; Triton-X 100. An aqueous solution contains cadmium sulphate as a cadmium and thiourea as sulphur precursor. Ammonia used as a complexing agent. The results of measurements of the x-ray diffraction, Raman spectroscopy, optical spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, Brunauer Emmett Teller (BET) surface areas and atomic force microscopy were used for the characterization of the films. These results revealed that the films are polycrystalline, consisting of CdS cubic phase. The films show a direct band gap with energy 2.39 eV. The films show interconnected nanowalls like morphology with well-defined surface area. Finally, the photoelectrochemical (PEC) performance of Triton-X mediated CdS thin film samples were studied. The sample shows photoelectrochemical (PEC) performance with maximum short circuit current density (J_sc) 1.71 mA/cm² for larger area (1 cm²) solar cells.     

Agglomeration of ZnS nanoparticles without capping additives at different temperatures

ZnS nanoparticles were precipitated in diluted aqueous solutions of zinc and sulphide ions without capping additives at a temperature interval of 0.5–20°C. ZnS nanoparticles were arranged in large flocs that were disaggregated into smaller agglomerates with hydrodynamic sizes of 70–150 nm depending on temperature. A linear relationship between hydrodynamic radius (R _a ) and temperature (T) was theoretically derived as R _a =652 - 2.11 T. The radii of 1.9–2.2 nm of individual ZnS nanoparticles were calculated on the basis of gap energies estimated from their UV absorption spectra. Low zeta potentials of these dispersions of ?5.0 mV to ?6.3 mV did not depend on temperature. Interactions between individual ZnS nanoparticles were modelled in the Material Studio environment. Water molecules were found to stabilize ZnS nanoparticles via electrostatic interactions.      

Energy Transfer Between Eu3+ Ions and CdS Quantum Dots in Sol-Gel Derived CdS/SiO2 : Eu3+ Gel

We have investigated the energetic correlation between rare-earth ions and semiconductor nanocrystals, using europium ion (Eu³⁺) doped silica (SiO₂) gel with adsorbed cadmium sulfide (CdS) particles. Samples were prepared by a sol-gel technique, in which several methods for the precipitation of CdS colloids were attempted. The fluorescence intensities were compared for different gels, with and without CdS particles. The intrinsic emission lines due to ⁵D₀ ⁷F_J(J = 0–4) transitions of Eu³⁺ were observed, which were enhanced for 24 h-immersed gel (dried at 50°C). From the results on the decay dynamics of fluorescence, we proposed the model that surface-trapped electrons on CdS particles nonradiatively excited 4f electrons in Eu³⁺ ions due to an energy transfer process.     

核壳结构CdS/ZnS纳米微粒的制备与光学特性

CdS and CdS/ZnS core-shell structure nano particles were synthesized in micro emulsion, and characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM), UV absorption spectra and PL. The average diameter of CdS was about 3.3 nm, and CdS/ZnS core-shell structure was confirmed by XRD and UV. Considering the optical properties of CdS/ZnS core-shell structure nanoparticles which have different ZnS shell thickness, the UV absorption edge of CdS/ZnS becomes as lightred-shift with the thickness of ZnS layer increasing, and the absorption of shortwave band is strongly enhanced at the same time. The PL spectra indicate that ZnS shell layer can greatly eliminate surface defects of CdS nanoparticles and make its band-edge directed recombination increased, and the luminous efficiency of CdS is improved greatly when it has appropriate shell thickness.     

The synthesis of ZnS hollow nanospheres with nanoporous shell

ZnS hollow nanospheres with nanoporous shell were successfully synthesized through the evolvement of ZnO nanospheres which were synthesized by hydrothermal method with poly (sodium-p-styrene sulfonate) (PSS) as surfactant at low temperature. The as-synthesized samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), UV/vis spectrum and N₂ adsorption. The results showed that the shell of as-synthesized ZnS hollow structure was composed of many fine crystallites and had a nanoporous structure with pore diameter about 4 nm demonstrated by N₂ adsorption/desorption isotherm. The sample possessed efficiency of photocatalytic degradation on X-containing (X=Cl, Br, I) organic pollutants.