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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Facile Microwave Approach for Synthesis of Copper–Indium Sulfide Nanoparticles and Study of Their Behavior in Solar Cell

CuInS₂ (CIS) nanoparticles (nps) were synthesized via a microwave approach by adding eight sulfur sources with a new copper precursor, [bis(acetylacetonato)copper(II)]; [Cu(acac)₂]. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible and photoluminescence spectroscopy. Band gap of as-synthesized nps was 2.1 eV that showed about 0.55 eV blue shift in comparison to its bulk type. As observed in other semiconductor systems, the optical absorption blue shift is associated with quantum confinement effects. Thin film of CIS was prepared by doctor’s blade technique and solar cell made from indium transparent oxide/CIS/CdS/Pt layers. I–V characterization was investigated for this cell and fill factor, open-circuit voltage (V _oc) and short-circuit current (I _sc) were achieved.     

In Situ Observation of the Thermally Induced Growth of Platinum‐Nanoparticle Catalysts Using High‐Temperature X‐ray Diffraction

Fundamental understanding about the thermal stability of nanoparticles and deliberate control of structural and morphological changes under reactive conditions is of general importance for a wide range of reaction processes in heterogeneous and electrochemical catalysis. Herein, we present a parametric study of the thermal stability of carbon‐supported Pt nanoparticles at 80 °C and 160 °C, with an initial particle size below 3 nm, using in situ high‐temperature X‐ray diffraction (HT‐XRD). The effects on the thermal stability of carbon‐supported Pt nanoparticles are investigated with control parameters such as Brunauer–Emmet–Teller (BET) surface area, metal loading, temperature, and gas environment. We demonstrate that the growth rate exhibits a complex, nonlinear behavior and is largely controlled by the temperature, the initial particle size, and the interparticle distance. In addition, an ex situ transmission electron microscopy study was performed to verify our results obtained from the in situ HT‐XRD study.     

Deposition of CuInS2 thin films using copper- and indium/sulfide-containing precursors through a two-stage MOCVD method

Copper indium disulfide (CuInS2; CIS) films were deposited on various substrates by two-stage metal-organic chemical vapor deposition (MOCVD) at relatively mild conditions, using Cu- and In/S-containing precursors without toxic H2S gas: first, a pure Cu thin film was prepared on glass or indium/tin oxide glass substrates by using a single-source precursor, bis(ethylbutyrylacetato)copper(II) or bis(ethylisobutyrylacetato)copper(II); second, on the resulting Cu film, tris(N,N-ethylbutyldithiocarbamato)indium(III) was treated to produce CIS films by a MOCVD method at 430 degrees C. In this process, their thicknesses and stoichiometries were found to be elaborately controlled on demand by adjusting the process conditions. The optical band gap of the stoichiometric CIS film was about 1.41 eV, which is in the near-optimal range for harvesting solar radiation energy.     

Nanocomposites composed of P3HT:PCBM and nanoparticles synthesized by laser ablation of a bulk PbS target in liquid

Nanoparticles synthesized by laser ablation of bulk target materials in liquids have ligand-free surfaces since no chemical precursors are used for their synthesis, and thus, they are ideally suited for applications in the fabrication of organic solar cells in which the properties of the interface between the nanoparticles and the polymer blend matrix largerly determine the exciton splitting and transport of carriers to the external electrodes, properties crucial for the device operation and performance. Narrow band gap semiconducting quantum dots can act as sensitizers, increasing the absorption of the device active layer in the infrared part of the solar spectrum. In this work, a bulk PbS target was laser ablated (450 fs, 1,064 nm, 1 kHz) in ethanol for the synthesis of nanoparticle colloidal solutions. The solutions exhibit a broad absorption which extends at the longest wavelength measured of ~1,700 nm and beyond. The nanoparticles were directly mixed with the blend P3HT:PCBM for the formation of nanocomposites. The nanocomposites with the nanoparticles exhibit lower transmission in the whole spectral range as compared to the blend without the nanoparticles.     

A Directed Route to Colloidal Nanoparticle Synthesis of the Copper Selenophosphate Cu3PSe4

The first colloidal nanoparticle synthesis of the copper selenophosphate Cu₃PSe₄, a promising new material for photovoltaics, is reported. Because the formation of binary copper selenide impurities seemed to form more readily, two approaches were developed to install phosphorus bonds directly: 1) the synthesis of molecular P₄Se₃ and subsequent reaction with a copper precursor, (P‐Se)+Cu, and 2) the synthesis of copper phosphide, Cu₃P, nanoparticles and subsequent reaction with a selenium precursor, (Cu‐P)+Se. The isolation and purification of Cu₃P nanoparticles and subsequent selenization yielded phase‐pure Cu₃PSe₄. Solvent effects and Se precursor reactivities were elucidated and were key to understanding the final reaction conditions.     

Preparation and Unique Electrical Behaviors of Monodispersed Hybrid Nanorattles of Metal Nanocores with Hairy Electroactive Polymer Shells

A versatile template‐assisted strategy for the preparation of monodispersed rattle‐type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA‐g‐P3HT hybrid nanorattles; PTEMA: poly(2‐(thiophen‐3‐yl)ethyl methacrylate; P3HT: poly(3‐hexylthiophene), was reported. The Au@silica core‐shell nanoparticles, prepared by the modified Stöber sol–gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core‐double shell nanospheres. Subsequent oxidative graft polymerization of 3‐hexylthiophene from the exterior surface of the Au@silica@PTEMA core‐double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA‐g‐P3HT nanospheres). The Au@air@ PTEMA‐g‐P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as‐prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write‐once‐read‐many‐times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA‐g‐P3HT+PS/ITO (ITO: indium‐tin oxide) sandwich thin‐film devices.     

Preparation,surface morphology,and optical properties of indium(III) oxide nanoparticles by thermolysis of indium–poly(vinyl alcohol) coordination polymer

First report on the preparation of well-dispersed, indium(III) oxide (In₂O₃) nanoparticles with 22–35?nm size by polymer thermolysis is presented. Indium–poly(vinyl alcohol) (PVA) coordination polymer films were prepared by ‘solution casting technique’ from the homogeneous aqueous solution of coordination polymer prepared using PVA and indium(III) nitrate as starting materials; subsequently the films were calcined at 550?°C to yield In₂O₃ nanoparticles. Both indium–PVA coordination polymer that served as the precursor and the titled nanoparticles were characterized by Fourier transform-infrared spectroscopy, photoluminescence (PL), powder X-ray diffraction (XRD), transmission electron microscopy, and thermal analysis. Room temperature PL spectra of the prepared indium oxide nanoparticles showed intense blue emissions around 360, 410 and 430?nm, characteristic of indium oxide nanoparticles due to oxygen vacancies. The lower energy PL emission decreases with an increase of indium(III) content in the precursor. The size of the nanoparticles calculated from line broadening of XRD pattern (cubic; JCPDS: 06-0416) was found to be around 24?nm. The average particle size of the synthesized nanoparticles increased with metal ion content in the precursor coordination polymer.     

Study of catalytic action of micro-particles and synthesized nanoparticles of CuS on cellulose pyrolysis

The catalytic action of copper sulfide (CuS) micro-particles and as-synthesized nanoparticles was studied on cellulose pyrolysis. The market procured CuS powder was used as micro-particles without any treatment. The CuS nanoparticles were synthesized at ambient temperature by simple wet chemical technique. Before using the micro-particles and nanoparticles for catalytic study, they were comprehensively characterized. The thermal analysis including catalytic properties of both the micro-particles and nanoparticles of CuS on cellulose pyrolysis was studied employing thermogravimetric (TG), differential thermogravimetric, and differential thermal analysis techniques. Prior to the study as catalyst in cellulose pyrolysis, the CuS micro- and nanoparticles were characterized by thermal analysis in inert atmosphere. The TG curves showed two steps and five steps decomposition having total mass loss of 29 and 42 % in case of CuS micro- and as-synthesized nanoparticles, respectively. The catalytic study in cellulose pyrolysis showed that the decomposition commences at temperature 295 °C for pure cellulose, 270 °C for cellulose mixed with 3 % CuS micro-particles and 205 °C for cellulose mixed with 3 % CuS nanoparticles. It clearly showed that the decomposition starting temperature decreased by 65 °C in case of cellulose mixed with CuS nanoparticles compared to cellulose mixed with CuS micro-particles. Thus, CuS nanoparticles act as better catalyst then CuS micro-particles in cellulose pyrolysis. The obtained results are deliberated in details.     

Highly Sensitive Determination of Butyl Xanthate in Surface and Drinking Water by Headspace Gas Chromatography with Electron Capture Detector

A highly sensitive and convenient method for the determination of butyl xanthate in surface water and drinking water was developed by headspace gas chromatography with electron capture detector (HS–GC–ECD). The analytical method was based on the decomposition of butyl xanthate under an acidic condition, generating carbon disulfide, which could be sensitively detected by gas chromatography with electron capture detector. The signal of CS₂ from the decomposition of potassium butyl xanthate was directly proportional to the concentration of potassium butyl xanthate over the range 0.7–100 ng/mL. The detection limit at a signal-to-noise ratio of three (S/N = 3) for potassium butyl xanthate was 0.3 ng/mL (~1.6 × 10⁻⁹ mol/L), which was more than two orders of magnitude lower than the popular UV methods and close to one order of magnitude lower than the similar headspace gas chromatography–mass spectroscopy method. The relative standard deviation (R.S.D.) within a day and in 3 days for potassium butyl xanthate at both 5 and 50 ng/mL was less than 4.7 %, suggesting good analytical performance of the present method. Good recoveries from 93.3 to 104.7 % were obtained from spiked surface and drinking water samples, indicating that the proposed HS–GC–ECD method was applicable for the quantification of butyl xanthate in surface and drinking water. Compared with other reported methods, the present method is highly sensitive, without sample preparation, and easily extended to the analysis of other xanthates.

     

Biomimetic synthesis of CuInS2 nanoparticles: Characterization,cytotoxicity, and application in quantum dots sensitized solar cells

CuInS₂ (CIS) nanoparticles have unique chemical, toxicological and optoelectronic properties that favor their technological applications. In the present work we report a novel one step biomimetic method for the aqueous synthesis of CIS nanoparticles, that is also low cost and environmentally friendly. This biomimetic method uses only CuSO₄ and InCl₃ as precursor salts, and the biological molecule glutathione as sulfur donor and stabilizer of the nanoparticles (NPs). The reaction is performed at low temperatures, under aerobic conditions and atmospheric pressure. CIS nanoparticles produced by our biomimetic method exhibit fluorescence emission between 650 and 700 nm when excited at 500 nm. A size between 10 and 15 nm was determined by Dynamic light scattering (DLS) and corroborated by electron transmission microscopy. X-ray diffraction analysis (XRD) confirmed the crystalline structure of the CIS NPs produced. Energy Dispersive X-Ray Spectroscopy (EDX) analyses revealed the presence of Cu, In, and S in a 0.6: 1.4: 2 ratio, which has been reported for other CIS NPs in literature. No cytotoxicity of CIS NPs was observed in human OKT6/TERT2 cells and bacteria. Besides, the potential application of biomimetic CIS NPs as photosensitizers in quantum dots sensitized solar cells (QDSSCs) was confirmed. The biocompatibility, spectroscopic properties, and energy harvesting performance in solar cells of the CIS NPs produced by our biomimetic method make them suitable for their use in different biotechnological applications.     

Radiation-assisted synthesis of iridium and rhodium nanoparticles supported on polyvinylpyrrolidone

The controlled synthesis of rhodium (Rh) and iridium (Ir) nanoparticles was carried out by gamma irradiation of aqueous solutions containing the metal precursor salt and polyvinylpyrrolidone (PVP). The nanoparticles were synthesized at various PVP and precursor concentrations with absorbed doses between 20 and 60 kGy. Nanoparticles with average sizes of 2.4 and 2.6 nm and narrow particle size distributions were obtained at metal precursor/PVP concentrations of 6/0.3 and 6/3 mM for Ir and Rh when irradiated at 60 kGy. The interaction of the nanoparticles surfaces with the PVP was studied.     

Synthesis and Characterization of Gold Nanoparticle‐Functionalized Ordered Mesoporous Materials

We report the synthesis and characterization of three different ordered mesoporous materials, labeled MCM‐48, SBA‐155, and SBA‐16 type materials, which were functionalized with gold nanoparticles using three different strategies. The functionalization strategies can be categorized as (i) in situ growth of gold nanoparticles, (ii) template loading, and (iii) diffusion loading of prefabricated gold nanoparticles. Two different particle sizes were employed in the latter two strategies, 5 nm and 10 nm. For all mesoporous structures, functionalization strategies, and particle sizes attempted, the materials retained their long‐range order upon incorporation of nanoparticles. From the adsorption isotherms, incorporation of gold nanoparticles altered the pore structure of the mesoporous support of some of the SBA‐15 and SBA‐16 type materials, with the effect on incorporation on the pore structure being particle size dependent in most cases. The majority of gold nanoparticles were found to reside on the external surface of the materials regardless of substrate and functionalization strategy; however, for the in situ synthesis and the template loading strategies, a significant fraction of the particles was determined to reside within the pore system of the material. In situ growth resulted in the highest content of gold nanoparticles in the solid phase. The relative effectiveness in retaining gold nanoparticles in the solid phase for each functionalization strategy was determined to be, in descending order, in situ synthesis, template loading, and diffusion loading.     

Thermal behaviour of precursors for CuInS2 thin films deposited by spray pyrolysis

The thermal decomposition of precursors for copper indium disulphide (CuInS₂) thin films obtained by drying aqueous solutions of copper chloride (CuCl₂), indium chloride (InCl₃) and thiourea (SC(NH₂)₂) at the Cu:In:S molar ratios of 1:1:3 (1) and 1:1:6 (2) was monitored by simultaneous thermogravimetry /differential thermal analysis/ evolved gas analysis-mass spectrometry (TG/DTA/EGA-MS) measurements in a dynamic 80 %Ar + 20 %O₂ atmosphere. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the dried precursors and products of the thermal decomposition. The precursors 1 and 2 are mixtures of copper and indium chloride thiourea complex compounds, whilst 1 can also contain unreacted InCl₃. The thermal degradation of 1 and 2 in the temperature range of 30–800 °C consists of six steps with a total mass loss of 71.5 and 89.8 %, respectively. According to XRD, CuInS₂ is formed below 300 °C. Decomposition of 1 and 2 is completed at 620 and 600 °C, respectively. The final decomposition product of 1 at 800 °C consists of a mixture of In₂O₃ and CuO phases, whilst 2 consists of In₂O₃, CuO and Cu₂In₂O₅ phases. EGA by MS revealed the release of CS₂, NH₃, H₂NCN and HNCS, which upon their oxidation also yield COS, SO₂, HCN and CO₂.     

Direct synthesis of indium nanoparticles and their application to prepare CuInS<Subscript>2</Subscript> thin films and solar cells

This paper reports a simple hot-injection method to prepare monodisperse indium nanoparticles which are applied as indium sources to prepare CuInS₂ thin films and solar cells. Indium nanoparticles with particle sizes of about 10 nm or even smaller are synthesized and are influenced by the stabilizing agent, reaction temperature and solvent, which can be elucidated by a burst nucleation and growth mechanism. Moreover, the inks from the indium nanoparticles are used to prepare compact and well crystallized CuInS₂ (CIS) films which are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and I–V measurement. Finally, the CIS solar cells are fabricated on the basis of the CIS films, and their efficiency is about 2.08%, which can be further improved by decreasing series resistance.     

Controllable Synthesis of Covellite Nanoparticles via Thermal Decomposition Method

In this study, covellite (CuS) nanoparticles were synthesized through a facile and low temperature thermal decomposition method using [Cu(sal)₂]- oleylamine complex, (sal = salicylaldehydeato, prepared in situ from [Cu(sal)₂] and oleylamine as the precursors), and sulfur as the Cu²⁺ source and S source, respectively. Scanning electron microscope, transmission electron microscope, electron diffraction and ultraviolet–visible absorption (UV–Vis) spectra were used for the characterization of the products. The effect of reaction parameters, such as the copper:sulfur molar ratio, the reaction temperature and the reaction time on the shape, size and phase of CuS nanostructures, was investigated. The results showed that the, covellite (hexagonal structure of CuS) with an average size between 20 and 45 nm could be obtained with the Cu:S molar ratio of 1: 3 at 105 °C for 60 min. With increasing the reaction temperature from 105 to 200 °C, non-stoichiometric Cu_1.65S with the average size of 25–50 nm was obtained due to the different existing state of the released Cu²⁺ ions from the copper-oleylamine complex.     

Investigation of the formation of CuInS2 nanoparticles by the oleylamine route: comparison of microwave-assisted and conventional syntheses

The formation of copper indium disulfide nanoparticles via the oleylamine route using copper iodide, indium chloride, and elemental sulfur has been investigated by applying conventional thermal heating as well as microwave irradiation. Oleylamine thereby acts as a capping ligand as well as a solvent. In an initial set of experiments, the onset of the reaction was determined to be around 115 °C by an in situ X-ray study using Synchrotron radiation. Using comparatively low synthesis temperatures of 120 °C, it is already possible to obtain nanoparticles of 2-4 nm with both heating methods but with irregular shape and size distribution. By applying higher temperatures of 220 °C, more crystalline and larger nanoparticles were obtained with slight differences in crystallite size and size distribution depending on the synthesis route. The size of the nanoparticles is in the range of 3-10 nm depending on the heating time. Using microwave irradiation, it is possible to obtain nanoparticles in only 90 s of total synthesis time. Control experiments to probe a nonthermal microwave effect were carried out ensuring an identical experimental setup, including the heating profile, the stirring rate, and the volume and concentration of the solutions. These experiments clearly demonstrate that for the preparation of CuInS(2) nanoparticles described herein no differences between conventional and microwave heating could be observed when performed at the same temperature. The nanoparticles obtained by microwave and thermal methods have the same crystal phase, primary crystallite size, shape, and size distribution. In addition, they show no significant differences concerning their optical properties.     

Indium doped zinc oxide nanopowders for transparent conducting coatings on glass substrates

Crystalline indium doped zinc oxide (IZO) nanopowders were synthesized using hydrothermal treatment processing. Increasing the doping ratio of indium in the zinc oxide significantly influences the phase structure and shape of the nanopowders resulting in nanorod to nanoparticulate morphologies. As the doping profile increases, the crystallite size decreases, the band gap energy blue shifts and the specific surface area increases (measured by BET method). Additionally Raman spectroscopy exhibited shifts of several peaks, as well as revealed new peaks, confirming the substitution of indium ions within the zinc oxide lattice sites. An IZO suspension made of IZO nanoparticles (In/Zn = 3 atm.%) with a zeta potential greater than 30 mV at pH = 6 was successfully spin-coated on glass substrates for to make transparent conductive coatings evincing sheet resistances as low as 35 kΩ_□ (ρ = 4.9 × 10^?3 Ω m,) with transmission in the visible range as high as 90 %.     

Nonhydrolytic sol–gel and gram-scale synthesis of surfactant-free maghemite nanoparticles with high surface area

An organic molecule was used as a surfactant for nanoparticle synthesis in liquid phase. However, residual molecules on the surface of the nanoparticles limit their catalytic applications, because the interaction of a reactant with the nanoparticle surface is interrupted. Therefore, it is favorable for catalytic applications that the organic molecule used in the synthesis of nanoparticles only induces a sol–gel reaction of the metal precursors and the formation of nanoparticles and hardly adheres to the resulting nanoparticles. Herein, we report surfactant-free and high-surface area maghemite nanostructures via nonhydrolytic sol–gel reaction. Using Fe(acetylacetonate)₃ as an iron precursor and hexylamine as a solvent and growth inhibitor, Fe₂O₃ nanoparticles were generated by nonhydrolysis of the iron complex and condensation at 140 °C under an air atmosphere. Characterization revealed monodisperse nanoparticles with an average size of 2.3 nm and a crystalline phase of maghemite. Residual hexylamine is hardly observed, and thus their specific surface area is 403.7 m²/g. An experimental comparison of the Fe₂O₃ synthesis with hexylamine and benzylamine indicates that the cone angle of an organic molecule is an important factor in the synthesis of nanoparticles with a small size and high surface area.     

Electrosynthesis and thermal characterization of basic copper carbonate nanoparticles

The present study concerns the electrochemical synthesis of basic copper carbonate nanoparticles by oxidation of metallic copper on the anode in an aqueous bicarbonate solution. This simple and one-step preparation can be considered as green synthesis. The scanning electron microscopy (SEM) analysis indicates that average particle size of the product is in the range of about 70 nm. On the other hand, basic copper carbonate micro-powder has been prepared, by mixing solutions of copper(II) sulphate and sodiu bicarbonate. The SEM analysis showed that the size of particles prepared in the same way is in the range of about 1 μm. In another part of this study, the thermal decomposition of micro and nanoparticles of copper carbonate produced by various methods was studied in air using TG-DTA techniques. The results of thermal study show that the decomposition of both samples occurs in single step. Also, the TG-DTA analysis of the nanoparticles indicates that the main thermal degradation occurs in the temperature range of 245–315°C. However, microparticles of Cu(OH)₂ · CuCO₃ decomposed endothermally in the temperature range of 230–330°C.