SILAR Cycles Research Articles

Synthesis and characterization of CuxCd1‐xS nanocrystals into functionalized nitrile butadiene rubber matrix

AbstractIntroductionPolymetallic sulfides and heterostructures like CdIn2S4, CdZnS2, CuxS‐NiySz, Cu2CoSnS4, CoNi2S4, Zn0.76Co0.24S have been fabricated with various shapes and forms for new applications. Ternary copper cadmium sulfides (CuCdS2) are a p‐type semiconductor with a direct band gap of about 2.4 eV forms very good nanocrystals like copper sulfide could be potentially applied to optical and electronic applications. Knowing that the SILAR synthesis, optical, paramagnetic, dielectric properties, and annealing of copper cadmium sulfides have not been sufficiently investigated, they are extensively analyzed and studied in the present work.ObjectivesCuxCd1−xS (x = 0, 0.5, and 1) nanoparticles have been synthesized on the base of functionalized nitrile butadiene rubber by SILAR method and characterized using scanning electron microscopy, x‐ray diffractometer, UV–visible spectroscopy, Fourier‐transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, and Raman spectroscopy. Effects of cycles, reaction time, and precursor concentration on the particle size, crystal growth and structure, bandgap energy, dielectric and paramagnetic properties, elemental composition, and morphology were investigated.MethodsThe synthesis of CuxCd1−xS nanocrystals was carried out into the obtained functional polymer matrix by SİLAR method. The functional polymer (FNBR) is a dark brown powder which contains ‐PO(OH)2 and ‐OPO(OH)2 functional groups and does not dissolve in organic and inorganic solvents, can be used as a very good stabilizer of nanostructures. The synthesis of CuxCd1−xS/FNBR nanocompsite was carried out in 3, 5, and 15 cycles.Results and discussionIn the process of ternary sulfide formation, the nucleation rate of CdS was high at the beginning of the reaction, while the growth rate and stability of CuS were high in the later course of the reaction. The average crystallite size of the nancrystallites has been increased from 1.13 nm to 7.39 nm by the increasing of the number of cycles from 5 to 15, respectively. It is explained by the inclusion of copper in the composition and getting more stable material. Copper cadmium sulfide nanostructures demonstrate wide band gap energy (~3.7 eV) in this work which is explained by the formation of nanosized particles in a limited volume of FNBR matrix.ConclusionsThe synthesis of CuxCd1‐xS nanocrystals was carried out into the obtained functional polymer matrix by SİLAR method. Strong diffraction peaks corresponding to cubic CdS are found with low SILAR cycles. SEM images of CuxCd1−xS/FNBR nanocomposite show that the atomic percentage of Cu and Cd into the ternary sulfide is 20.19% and 0.61%, respectively. It is explained by the inclusion of copper in the composition and getting more stable material with low solubility products (Ksp) which is in good agreement with XRD results. The calculated band gaps are higher than that of bulk CdS, CuS, and CuCdS2. Larger band gap is usually reported for defects or structural disorders, which is in good agreement with XRD and Raman results.

Synthesis of Iron Copper Sulphide (FeCuS) Thin Film and its Characterization

The Influence of SILAR cycle on the optical, morphological as well as compositional properties of Iron Copper Sulphide (FeCuS) thin film was reported. Utilizing the straightforward and reasonably priced SILAR technique, the deposition was carried out by the use of soda lime glass (SLG) substrates. With a concentration of 1.0M for Iron (Fe) ions, the deposition process was repeated 50, 60, and 70 times, with an 80-seconds dip time per cycle. Morphological characterization of the thin film was analyzed with Scanning Electron Microscopy (SEM) instrument. The compositional properties were analyzed with Energy Dispersive X-Ray machine. A UV-VIS Spectrophotometer was utilized to examine the thin film's optical characteristics. The presence of deposited thin film samples is confirmed by the SEM results, which display higher peaks for the elements Fe, Cu, and S. The results of the EDX analysis demonstrated that an increase in concentration enhances the homogeneity and adhesion of the deposited films in addition to their crystallinity. It was discovered that the thin film's energy band gap for each SILAR cycle was 0.9 eV, 1.3 eV, and 2.99 eV respectively.

Transparent TiO2 nanotubes supporting silver sulfide for photoelectrochemical water splitting.

Differences between photoelectrochemical and electrochemical activity were thoroughly investigated for the oxygen evolution reaction mediated by Ag2S deposited on two types of ordered titania substrates. Titanium dioxide nanotubes were fabricated by anodization of magnetron sputtered Ti films on ITO-coated glass substrates or directly from Ti foil. Further, Ag2S deposition on the nanotubes was carried out using successive ionic layer adsorption and reaction, known as SILAR, with 5, 25, and 45 cycles performed. Two types of nanotubes, one on transparent the other on non-transparent substrates were compared regarding their geometry, structure, optical, and electrochemical properties. It was demonstrated that the composite of Ag2S grown on transparent nanotubes exhibits higher catalytic activity compared to Ag2S grown on the nanotubes formed on Ti foil. The results showed that transparent nanotubes after modification with Ag2S by 25 SILAR cycles exhibit ca. 3 times higher photocurrent under visible light illumination than non-transparent ones treated with the same number of cycles. Furthermore, transparent nanotubes after 45 SILAR cycles of Ag2S exhibit enhanced activity towards oxygen evolution reaction with 9.3 mA cm-2 at 1.1 V vs. Ag/AgCl/0.1 M KCl which is six times higher than titania alone on Ti foil.

Impact of number of sensitizer SILAR cycles on the performance of ZnO based PbS quantum dot-sensitized solar cells

Impact of number of sensitizer SILAR cycles on the performance of ZnO based PbS quantum dot-sensitized solar cells

Stable Ta2O5 nanotubes decorated by PbS by the SILAR method for photocatalytic dye degradation

Tantalum oxide Ta2O5 nanotubes (NTs) were prepared by electrochemical anodization and were decorated with lead sulfide nanoparticles PbS (NPs) by Successive Ionic Layer Adsorption and Reaction commonly known as the SILAR method. The PbS NPs/Ta2O5 NTs were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDX), Transmission Electron Spectroscopy (TEM), Photoluminescence (PL), and Diffuse Reflectance Spectroscopy (DRS). An increasing number of SILAR cycles applied on this substrate were shown to induce a variation in the optical properties and the bandgap of PbS NPs/Ta2O5 NTs. The bandgap went from 3.83 eV for bare Ta2O5 to 3.4 eV for Ta2O5 NTs decorated with 10 PbS SILAR cycles. Ten SILAR cycles were seen to correspond to 2.7 wt% and 1.4 M percentage of the decorated Ta2O5 NTs. Ten SILAR cycles were required to drive the fastest degradation kinetics of the Black Amido mediating Ta2O5 (NTs)-PbS NPs under light irradiation. However, longer SILAR cycles were not seen to faster the degradation kinetics due to light screening. The prepared nanotubes exhibited high stability over 5 photocatalytic reuse cycles.

Green synthesis of tin sulfide films for potential applications in supercapacitors and the effect of annealing

Tin sulfide has been widely studied as electrode materials for supercapacitors owing to their high theoretical pseudocapacitance. This paper reports a novel green synthesis of tin sulfide nanoparticles as a substrate using FTO glass slides. Moreover, the material characterization with respect to the morphology (scanning electron microscopy), phase composition (X-ray diffraction), crystallinity and molecular interactions (Raman spectroscopy) and electric (electrochemical performance) properties were provided. After annealing at 300 °C, smooth and well-adhered tin sulfide films were formed, consisting of smaller spherical particles 28–37 nm in size, and the thickness of annealed films is in the interval of 230–280 nm, depending on the number of tin sulfide synthesis cycles and the amount of complexing agent. According to Raman spectroscopy results, annealed films consist of SnS with secondary SnS2 or Sn2S3 phase. The obtained material was used for electrochemical calculations for supercapacitor application, and a significant increase of energetic values was seen after the annealing of films. The highest values of energetic parameters during this work have been provided by tin sulfide film synthesized with 1.0 g of L-ascorbic acid using 20 SILAR cycles.

Enhancing the photoelectrochemical performance of ZnO nanopagoda photoanode through sensitization with Ag and Ag2S NPs co-deposition

ZnO nanopagoda arrays (NPGs) modified with Ag and Ag2S nanoparticles (NPs) were fabricated using aqueous downward growth and SILAR techniques and investigated as photoanodes for the photoelectrochemical system. The crystal structure, morphology, elemental composition, optical characteristics, and photoelectrochemical performance of the fabricated samples were studied. The obtained results disclosed that the successful deposition of Ag and Ag2S NPs on ZnO NPGs’ surface not only enhanced the visible light-harvesting but also promoted the e−/h+ separation and injection. In addition, various SILAR cycles were investigated. The optimum eight SILAR cycles for Ag–Ag2S NPs deposition on ZnO NPGs achieved the maximum photocurrent of 2.91 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE), about five folds superior to that of bare ZnO NPGs. It also demonstrated the improved applied bias photon-to-current conversion efficiency of 0.43% at 0.6 V vs. RHE. The charge transfer and PEC mechanisms for the fabricated ZnO NPGs/Ag–Ag2S NPs photoanodes were also proposed. This study offers a facile fabrication of a distinctive ZnO NPGs morphology and an improvement of the PEC performance through the synergistic effect of the LSPR effect of Ag NPs and visible light sensitization of Ag2S NPs.

Photocatalytic applications of heterostructure Ag2S/TiO2 nanotube arrays for U(VI) reduction and phenol degradation

The photocatalytic reduction of U(VI) is an efficient strategy for dealing with uranium-containing wastewater. Herein, a heterostructure material of Ag2S deposited in titanium dioxide nanotube arrays (Ag2S/TNTAs) was prepared by the successive ionic layer adsorption method (SILAR) and applied as an effective photocatalyst for U(VI) reduction. Compared with pure TNTAs, the Ag2S/TNTAs-7 (the number of SILAR cycles) achieved the optimal photoreduction rate of 94% for U(VI) with the rate constant of 0.0105 min−1, which was a 21-fold boost over TNTAs. Impressively, the photocatalytic reduction process of U(VI) by Ag2S/TNTs-7 could be achieved without any sacrifice agents. Furthermore, phenol was introduced to replace the action of methanol, which would not only enhance U(VI) removal efficiency, but also realize degradation of phenol. Mechanism studies have shown that photogenerated electrons and ·O2− act as the reactive species to reduce U(VI) to immobile (UO2) O2⋅2H2O. This work paves a feasible pathway for treatment of uranium-containing wastewater and also demonstrates the potential application prospect of Ag2S/TNTAs-7 in the treatment of organic pollutants.

Enhancement in absorption spectrum by ITO coated, down converting glass as a photoanode substrate for efficient PbS/CdS quantum dots sensitized ZnO nano-rods array solar cell

An efficient, simple and cost effective architecture of PbS/CdS quantum dots sensitized ZnO nano rods array solar cell has been proposed. A normal glass substrate in photoanode has been replaced by down converting glass to broad the absorption spectrum of solar cell. Three PbS/CdS quantum dots sensitized ZnO nano rods array solar cells with ITO coated down converting glass as a substrate have been fabricated by changing 10, 15 and 20 SILAR cycles for PbS/CdS quantum dots sensitization. SEM analysis confirmed the formation of ZnO nano rods. Grown nano rods were not closely packed which provided PbS/CdS quantum dots proper surface area to get attached. Optical properties analyzed by UV–Visible spectroscopy revealed the optical absorption in UV range which eventually was converted in visible spectra by down converting glass also the ZnO nano rod arrays increased the possibility of light scattering hence improved light absorption. The purposed architecture of solar cell hence played important role to achieve high power conversion efficiency of 8.6%.

Ti/TiO2 nanotubes sensitized PbS quantum dots as photoelectrodes applied for decomposition of anticancer drugs under simulated solar energy

One of the challenges in research into photoelectrocatalytic (PEC) degradation of pollutants is finding the appropriate photoanode material, which has a significant impact on the process efficiency. Among all others, photoelectrodes based on an ordered TiO2 nanotube arrays are a promising material due to well-developed surface area and efficient charge separation. To increase the PEC activity of this material, the SILAR method was used to decorate Ti/TiO2 nanotubes by PbS quantum dots (QD). The ifosfamide (IF) degradation rate constants was twice as higher for PbS-Ti/TiO2 (0.0148 min−1) than for Ti/TiO2 (0.0072 min−1). Our research showed the highest efficiency of PEC degradation of drugs using IIIPbS-Ti/TiO2 made with 3 SILAR cycles (PbS QD size mainly 2–4 nm). The 4 and 6 of SILAR cycles resulted in the aggregation of PbS nanoparticles on the Ti/TiO2 surface and decreased IF PEC degradation rate to 0.0043 and 0.0033 min−1, respectively. Research on PEC mechanism has shown that the drugs are degraded mainly by the activity of photogenerated holes and hydroxyl radicals. In addition, the identified drug intermediates made possible to propose a degradation pathways of anticancer drugs and the ecotoxicity test show no inhibition of Lemna minor growth of treated solutions.

Construction of IrO2@Mn3O4 core-shell heterostructured nanocomposites for high performance symmetric supercapacitor device

In the present work, we have designed and synthesized nanocomposite of IrO2@Mn3O4 with two-step simple and scalable chemical routes. In this route, nanofibers of IrO2 were synthesized by a single nozzle electrospinning technique onto which Mn3O4 was overlaid by a simple SILAR route. The ratio of Mn3O4 and IrO2 was varied by varying the SILAR cycles onto electrospun IrO2 thin film as 20, 40, 60, and 80 cycles. The structural, morphological, and energy storage performance of IrO2@Mn3O4 composite electrodes were investigated. A 2 V kinetic potential with a rectangular-shaped cyclic voltammogram was observed for the IrO2@Mn3O4 electrodes. Moreover, the specific capacitance of 1027 F/g at 1 mA/cm2 was observed for the optimized electrode which is superior as compared with other electrodes. The optimized electrode showed better current and voltage than the individual compounds which might be due to the synergic effect of IrO2 and Mn3O4. Finally, a PVA-LiClO4 gel electrolyte-based solid-state IrO2@Mn3O4//IrO2@Mn3O4 symmetric device was fabricated. The symmetric device possessed an energy density of 81 Wh/kg with a power delivery of 714 W/kg which was capable to light up a green LED. Hence, the 2D transition metal oxides laminated on 1D metal oxides with high conductivity can be promising electrodes for future research.

Effect of Different Silar Cycle on Chemically Deposited ZINC Copper Sulphide (ZnCuS)

Effect of Different Silar Cycle on Chemically Deposited ZINC Copper Sulphide (ZnCuS)

Results of SILAR Cycles Variation on the Optical, Structural and Electrical Properties of Lead Iodide Thin Films

Results of SILAR Cycles Variation on the Optical, Structural and Electrical Properties of Lead Iodide Thin Films

A novel, PbS quantum dot-Sensitized solar cell structure with TiO2-fMWCNTS nano-composite filled meso-porous anatase TiO2 photoanode

The research deals with fabrication of a novel quantum dot sensitized solar cells (QDSSC) architecture. Three devices, device 1, 2 and 3 with TiO2-fMWCNTs nano composite filled meso porous anatase TiO2 photoanodes, sensitized with PbS by 10, 15 and 20 SILAR cycles respectively were prepared. Decrease in optical band gap has been observed by increasing the SILAR cycles for PbS sensitization. QDSSC with TiO2-fMWCNTS nano-composite filled meso-porous anatase TiO2 photoanode showed a significant energy conversion efficiency of 3.8%, 5% and 5.6% for device 1, 2 and 3 respectively under the simulated light of 100 mW cm−2 with AM 1.5 filter. EIS analysis revealed that the device with highest power conversion efficiency has highest charge combination resistance (Rcr) 2852 Ω.

An investigation on the photovoltaic performance of quantum dot solar cells sensitized by CdTe, CdSe and CdS having comparable size

Abstract Quantum dot sensitized solar cells (QDSSC) have been fabricated with CdTe, CdSe and CdS quantum dots (QDs) of nearly similar size as the photosensitizers. The optical and structural characteristics were studied using absorption spectroscopy, XRD and TEM. Efficiency of the fabricated solar cells was found to improve by the incorporation of an additional buffer layer of ZnS. The value of efficiencies for the QDSSCs corresponding to the sensitizers CdTe, CdSe and CdS are 0.22%, 0.25% and 0.20%. After treatment with ZnS using SILAR cycle, an enhacement in the efficiency to 1.41%, 1.98% and 0.94% was noticed for the QDSSC sensitized with CdTe, CdSe and CdS QDs respectively. The differences in efficiencies as well as other photovoltaic parameters for the solar cells have been explained using the differences in effective masses of charge carriers and carrier lifetime in the three different QD samples. CdSe is found to have high adsorption property towards ZnS compared to CdTe or CdS QDs. Also, the ZnS buffer layer acts as a good agent for reducing the back scattering of electrons thereby improving the efficiency of all the three QD solar cells.

EFFECT OF CYCLE COUNT IN SILAR DEPOSITION OF COUNTER ELECTRODE ON THE PERFORMANCE OF QUATERNARY QUANTUM DOT SENSITIZED SOLAR CELL

Cu-Ni-S alloyed films of different thicknesses were prepared by varying the number of cycles in SILAR deposition and were used for the application as Counter Electrode in QDSSCs. For device fabrication, titanium dioxide films were used as a photo-anode layer, Cu2ZnSnS4 quaternary quantum dots as a sensitizer, and polysulfide electrolyte was used as Redox mediator. The effect of number of SILAR cycles on the electrical and electrochemical parameters was studied with V-I characteristic curve and electrochemical impedance spectroscopy. The device incorporating counter electrode deposited by 10 SILAR cycles performed best among other devices because of its lowest impedance parameters.

Enhancement of photocatalytic and photoelectrochemical properties of TiO2 nanotubes sensitized by SILAR - Deposited PbS nanoparticles

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO2 nanotubes (TiO2-NTAs) by sensitizing them with PbS nanoparticles (NPs) prepared by the Successive Ionic Layer Adsorption and Reaction method (SILAR). The Microstructure, surface morphology, phase composition and optical properties of the prepared structure were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM and High-resolution mode HRTEM) and X-ray photoelectron spectroscopy (XPS). The TiO2 NTAs were loaded by PbS NPs, which contents increase by increasing the number of SILAR cycles. The PbS NPs, which have a size in the order of ∼20 nm, were found to be uniformly distributed in the TiO2 NTAs without damaging the tubular ordered structure. The photocatalytic activity of the PbS/TiO2 NTAs system, toward Amido Black (AB), showed significant enhancement compared to the bare untreated TiO2 NTs. At 30 SILAR deposition cycles the PbS-NPs/TiO2 NTAs structure is able to remove 75% of BA under simulated solar light, considerably higher than the 40% removal obtained with unloaded TiO2 NTAs. A significant improvement of the Photoelectrochemical (PEC) efficiency has been also demonstrated for the PbS-NPs/TiO2 NTAs hybrid system. This improvement is mainly related to visible-light harvesting and reduced recombination of photo-generated electron-hole pairs due to the synergistic effect of the heterojunction and to the well-organized morphology of the TiO2 NTAs.

High-performance symmetric supercapacitor; nanoflower-like NiCo2O4//NiCo2O4 thin films synthesized by simple and highly stable chemical method

In this study, flowers-like interconnected nanoflakes NiCo2O4 thin films were synthesized by the SILAR method for the fabrication of supercapacitor application. X-ray diffraction analysis revealed that the synthesized NiCo2O4 thin films exhibit polycrystalline nature, and FE-SEM images confirmed their highly porous-like surface area. The analysis of structural, elemental, and compositional properties of the NiCo2O4 thin films were confirmed, that the thin films were used as electrode material for supercapacitor applications used as electrode material for supercapacitor testing. As expected, the prepared NiCo2O4 thin films showed high stability and served as efficient materials for use in supercapacitors application. The NiCo2O4 thin films exhibited excellent cycling charge-discharge with a specific capacitance (CS) of 1936 F g−1 at a scan rate of 5 mV s−1 in a 3 M KOH electrolyte. Cycling stability results revealed that NiCo2O4 thin films exhibit highly stable performance with a 94.5% retention. Symmetric supercapacitor performance presenting an energy density of 294.54 kW h kg−1 and power density 7.8 W kg−1, it indicates the NiCo2O4 based electrode is applicable for the practical applications in device fabrication of asymmetric and symmetric supercapacitor. The high performance of the NiCo2O4 thin films is possibly related to the presence of a highly porous surface morphology and stepwise effects of the SILAR cycle.

Effect of Surface Modification on SILAR Deposited CdS Quantum Dot Sensitized Hydrothermally Synthesised Titania Nanostructure

In the present work titaniana noflakes-nanorods were prepared on a flexible titanium metal foil by modified hydrothermal method. The titania nanoflakes-nanorods were further sensitized with CdS quantum dots through SILAR deposition. The surface charge of the titania surfaces were tuned using triethanolamine (TEA) to obtain maximum loading of CdS particles on the surface. The samples were characterized by XRD, FE-SEM and EDX analysis, which confirms the enhanced deposition of CdS quantum dots on the titania surface by TEA modification. The visible light photocatalytic studies were done by methylene blue degradation study. The modification in the SILAR cycle using TEA improves the photocatlytic performance around 4 times than those without TEA. The OH.radical formed in the photocatalytic reaction followed by photoluminescence study.

Hidden energy levels? Carrier transport ability of CdS/CdS1-xSex quantum dot solar cells impacted by Cd-Cd level formation.

In quantum dot sensitized solar cells (QDSSC), a cascade energy level structure controlled by assembly of cadmium-chalcogenide quantum dots can remarkably improve the sunlight harvesting and charge carrier lifetime. Despite the advantages of using co-sensitizers, energy conversion efficiencies are still low. An increased understanding of the causes of the low photoconversion efficiency (PCE) will contribute to the development of a straightforward approach to improve solar cell performance by exploiting co-sensitization. Herein we discuss how an excess of cadmium causes structural disorder and defect levels impacting the PCE of QDSSC devices. Thus, outer CdS1-xSex/inner CdS QD-co-sensitized B,N,F-co-doped-TiO2 nanotubes (BNF-TNT) were prepared. Chalcogenides were deposited by the SILAR method on BNF-TNT, varying the load of CdS as the inner sensitizer, while for CdS1-xSex, five SILAR cycles were used (5-CdS1-xSex), controlling the nominal S/Se molar ratio of the ternary alloy. Cd defects named as Cd-Cd energy levels were observed during CdS sensitization. Although incorporation of outer CdS1-xSex provides a tunable band gap to achieve good band alignment for carrier separation, Cd-Cd energy levels in the sensitizers act as recombination centers, limiting the overall electron flow at the BNF-TNT/CdS/CdS1-xSex interface. A maximum PCE of 2.58% was reached under standard AM 1.5G solar illumination at 100 mW cm-2. Additional limitations of SILAR as a deposition strategy of QDs are also found to influence the PCE of QDSSC.