Thiourea Content Research Articles

Structural, surface morphology and novel gas sensing properties of chemically deposited CdS-PVA nanocomposites; Impact of thiourea content

In this work, the impact of thiourea (TU) concentration (0.1, 0.15, and 0.2) M on the structure, surface topography, and morphology of CdS-PVA nanocomposites NCs thin film was investigated. Crystal structure (XRD) results revealed that all films had a polycrystalline structure of CdS phase with the presence of PVA wide peak at 2θ 22°. The crystallite size was increased (10–14) nm with an increase in the TU concentrations. The AFM results revealed that the film's roughness and the Root Mean Square (RMS) roughness was increased as TU concentrations increased. The FESEM results showed that the surface morphology of CdS-PVA films tends to be porous structures, and the pore size increases with the increase of TU concentration. The fabricated CdS-PVA nanocomposite gas sensors were tested at operating temperatures of (100, 200, and 300) °C. The results showed a high sensitivity for NO2 gas at an operating temperature of 200 °C for the TU concentration of 0.2 M and the sensitivity increased as the NO2 gas concentration increased. The novel results are connected with the fabrication of CdS-PVA nanocomposites as good nitrogen dioxide sensors.

Wild Heterotrophic Nitrifying Strain Pseudomonas BT1 Isolated from Kitchen Waste Sludge Restores Ammonia Nitrogen Removal in a Sewage Treatment Plant Shocked by Thiourea

Thiourea is used in agriculture and industry as a metal scavenger, synthetic intermediate, and nitrification inhibitor. However, in wastewater, it can inhibit the nitrification process and induce the collapse of the nitrification system. In such a case, ammonia-oxidizing bacteria (AOB) lose their ability to remove ammonia. We investigated the nitrification system of a 60,000-t/d municipal sewage treatment plant in Nanjing, which collapsed after receiving 5–15 ppm (5–15 mg/L) thiourea. Ammonia nitrogen removal quickly recovered to more than 95% after inoculation with 10 t high-efficiency nitrification sludge, which was collected from a kitchen waste treatment plant. A heterotrophic nitrification strain was isolated from the inoculated sludge and identified as wild Pseudomonas by 16S rDNA sequencing and named “BT1.” Based on thiourea tolerance tests, BT1 can tolerate a thiourea content of more than 500 ppm. For comparison, the in situ process was imitated by the simulation system, and the wastewater shocked by 10 ppm thiourea could still meet the emission standard after adding 1% (V/V) BT1. High-throughput sequencing analysis was applied to study microbial succession during thiourea shock loading. The results showed that Hydrogenophaga and Thiobacillus grew with the growth of BT1. Pseudomonas BT1 was used for a 6,000-t/d printed circuit board (PCB) wastewater treatment system, the nitrification system returned to normal in 15 days, and the degradation rate stabilized at more than 95%.

Sustainable development through restoration of Prosopis juliflora species into activated carbon as electrode material for supercapacitors

A route in this study has opened up by a successful transformation of Prosopis juliflora into N, S-dual doped activated carbon (AC) enhances biomass for supercapacitor applications. The method of restoration has opened up the possibility of sustainable development. This attempt explored the handling of biowaste and transforming into AC by simple hydrothermal method. The suitable amount of raw material with KOH, the activation state and the influence of thiourea content in the precursor are the important metrics in this translation method. The surface morphology and chemical mapping were examined. X-ray diffraction (XRD), Raman spectra and Brunaeur-Emmet-Teller (BET) are also examined. The proportion of 30 wt% of KOH activated with the temperature range of 400 °C, 500 °C, and 600 °C. The optimal PJ3 sample present surface area of 570.54 m2/g, benefiting at 1 A/g, the maximum specific capacitance of 246 F/g. The excellent stability of the sample over 3000 consecutive charge/discharge cycles with 96.74% capacitance retention shows the possibilities of using invasive plant Prosopis juliflora for supercapacitor application and a viable management strategy.

CuO/CuxS composites fabrication and their thermoelectric properties

Herein, copper oxide/copper sulfide (CuO/CuxS) composites have been prepared by treating CuO with thiourea by an aqueous hydrothermal route and their thermoelectric properties are studied. The electrical conductivity is improved with the increase in thiourea content, as a result, thermoelectric power factor increased from 10–4 to 101 µW m−1 K−2, and thermal conductivity of the CuO is also found to decrease with thiourea treatment. A detailed analysis indicated that these changes are due to the formation of copper sulfide (CuxS) in the CuO compound; a small fraction of electrically good conducting CuxS in the bulk CuO has produced composites with better electrical conductivity. These low-cost and non-toxic materials can be useful in thermoelectric energy conversion applications.

Effect of Thiourea on Electrodeposited Co–Mg–Nd Alloy Coating in Deep Eutectic Solvents

Potentiostatic technique was used to investigate the effect of additive thiourea on the deposition mechanism of Co2+ in choline chloride–urea eutectic solvent system. The Co–Mg–Nd ternary alloy coating was prepared by linear scanning technique which was used to study the electrochemical behavior of Co2+, Mg2+ and Nd3+ in the system and the corrosion resistance of alloy coatings. The results show that Co2+ follows the growth mechanism of three-dimensional continuous nucleation in choline chloride–urea eutectic system. When the amount of thiourea added exceeds 300 mg, the nucleation mode of Co2+ approaches the three-dimensional instantaneous nucleation. The cathodic polarization curves of Co2+, Mg2+, and Nd3+ in the choline chloride–urea system shows a trend of weakening first and then increasing with the increase of thiourea content. At the addition of 100 mg, the cathodic polarization of the films was the strongest, which was conducive to deposite. According to the Ecorr and Icorr obtained by tafel curve, it is found that adding thiourea in the plating solution system could change the corrosion resistance of the coating. When the content was less than 100 mg, the corrosion resistance of the coating is the best. With the thiourea content increasing, the corrosion resistance of the coating is gradually weakening. It is found that the plating solution with 100 mg thiourea added can prepare Co–Mg–Nd ternary alloy coating with excellent coating morphology, high rare earth content and stable compound, by SEM, EDX and XRD analysis.

Crystallinity Improvement of Co3O4 by Adding Thiourea

Tricobalt tetraoxide (Co3O4) samples having different thiourea/Co molar ratio of 0, 5 and 10 were prepared by wet chemical synthesis. The effects of thiourea content on the crystal structure-related parameters of Co3O4 were determined. The increase in the amount of thiourea caused a gradual decrease in the lattice parameters and specific surface area and an increase in the crystallinity and crystallite size. The experimental analysis results showed that thiourea content can be used to control the crystal structure-related parameters of Co3O4.

Microwave-Assisted Synthesis of Amikacin Modified N,S co-Doped Carbon Dots for Escherichia coli Detection

Fluorescent amikacin modified nitrogen, sulfur co-doped carbon dots (amikacin modified N,S-CDs) were synthesized by a facile and low-cost one-step microwave-assisted specifically for selective detection of Gram-negative bacteria Escherichia coli (E. coli). Amikacin is a semi-synthetic amino glycoside antibiotic and it was employed in this study to increase the fluorescence response of N,S-CDs by providing binding ligand towards E. coli. The effect of thiourea content as the source of nitrogen and sulfur dopants was investigated prior to the preparation of amikacin modified N,S-CDs. The formation of amikacin modified N,S-CDs were characterized by using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Transmission electron microscope (TEM), UV-Vis spectrophotometer, and spectrofluorometer. Amikacin modified N,S-CDs was identified to be successfully synthesized from the wavenumber shift of the C=O stretching mode. Amikacin modified N,S-CDs were amorphous with an average size of 7 nm. Fluorescence spectra showed that the highest intensity was obtained at thiourea content of 50% and amikacin mass of 25 mg. By comparing fluorescence responses of all the investigated amikacin modified N,S-CDs, the limit of detection (LOD) was attained by 25 mg amikacin modified N,S-CDs at 1.526 cfu mL−1.

Influence of thiourea on electroless Ni–P films deposited on silicon substrates

Electroless nickel–phosphorus films were produced on silicon substrates in alkaline bath solutions, with the addition of thiourea in a concentration range of 1.0–5.0 mg L−1. The influence of thiourea on the chemical composition, morphology and corrosion resistance of the films was studied. The results revealed thiourea had a major influence on plating rate, phosphorus-content and aggregate size. The optimal content of thiourea was 1 mg L−1. Thiourea accelerated the deposition rate at low concentration of 1 mg L−1, but deceased the deposition rate and the phosphorus content at high concentration. The surface of the film without thiourea was smooth and dense. Also, with increasing thiourea content, the surface evolved into coarse nodular morphology with clear intercolonial boundaries. With the addition of 1 mg L−1 thiourea, the film had better corrosion resistance compared to film without thiourea.

Solution combustion synthesis of nickel sulfide composite powders

Nickel sulfide powders were synthesized through solution combustion method using a suitable combination of thiourea fuel as reducing/sulfidizing agent with glycine fuel as auxiliary reductant agent. Effects of fuel contents on the combustion behavior, phase evolution, microstructure and optical properties were investigated by infrared spectroscopy, thermal analysis, X-ray diffractometry, electron microscopy and diffuse reflectance spectrometry techniques. Single phase NiS2 powders were formed using thiourea fuel at higher content, while a mixture of nickel sulfide phases was appeared in the presence of glycine fuel. The amount of different sulfide phases was considerably dependent on the thiourea content. Particle size of the as-combusted powders increased with the increase of thiourea; while the existence of glycine fuel together with thiourea led to the bulky microstructure. Maximum photodegradation (~ 56%) of methylene blue was achieved by as-combusted powders at a thiourea fuel to the oxidant molar ratio of 1, as a consequence of their high ability of light absorption.

ZnO-ZnS Heterojunctions: A Potential Candidate for Optoelectronics Applications and Mineralization of Endocrine Disruptors in Direct Sunlight.

Simple solution combustion synthesis was adopted to synthesize ZnO–ZnS (ZSx) nanocomposites using zinc nitrate as an oxidant and a mixture of urea and thiourea as a fuel. A large thiourea/urea ratio leads to more ZnS in ZSx with heterojunctions between ZnS and ZnO and throughout the bulk; tunable ZnS crystallite size and textural properties are an added advantage. The amount of ZnS in ZSx can be varied by simply changing the thiourea content. Although ZnO and ZnS are wide band gap semiconductors, ZSx exhibits visible light absorption, at least up to 525 nm. This demonstrates an effective reduction of the optical band gap and substantial changes in its electronic structure. Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and secondary-ion mass spectrometry results show features due to ZnO and ZnS and confirm the composite nature with heterojunctions. The above mentioned observations demonstrate the multifunctional nature of ZSx. Bare ZSx exhibits a promising sunlight-driven photocatalytic activity for complete mineralization of endocrine disruptors such as 2,4-dichlorophenol and endosulphan. ZSx also exhibits photocurrent generation at no applied bias. Dye-sensitized solar cell performance evaluation with ZSx shows up to 4% efficiency and 48% incident photon conversion efficiency. Heterojunctions observed between ZnO and ZnS nanocrystallites in high-resolution transmission electron microscopy suggest the reason for effective separation of electron–hole pairs and their utilization.

The effect of additional sulfur on solution-processed pure sulfide Cu2ZnSnS4 solar cell absorber layers

ABSTRACTTo reduce the amount of chalcogen needed in the post-annealing process, we demonstrate significantly increased sulfur incorporation into pure sulfide CZTS films achieved by increasing the thiourea content of DMSO-based precursor solution. The increase of sulfur content was confirmed by thermogravimetric analyses (TGA). To understand how the elemental distribution across the CZTS layer is affected by extra thiourea, a systematic compositional study was carried out using X-ray photoelectron spectroscopy (XPS). XPS depth profiling reveals increased sulfur incorporation in the final CZTS films when more thiourea is added to the solution. The grain size was reduced slightly with increased sulfur content and the surface morphology was changed significantly. The effect on the surface of the CZTS film has been investigated using scanning electron microscopy (SEM), Raman spectroscopy, and XPS. External-quantum-efficiency (EQE) measurements with an electrolyte contact were used to investigate the optoelectronic properties of the deposited CZTS films.

Visible light-responded C, N and S co-doped anatase TiO2 for photocatalytic reduction of Cr(VI)

The (C, N and S) co-doped TiO2 (TH-TiO2) samples were synthesized by a sol-gel method calcined at 500 °C, employing butyl titanate as the titanium source and thiourea as the dopant. The structures of TH-TiO2 samples were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectroscopy, Thermo gravimetry and differential thermal analysis (TG-DTA), Scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The photocatalytic activities were checked through the photocatalytic reduction of Cr(VI) as a model compound under visible light irradiation. The results showed that the thiourea content played an important role on the microstructure and photocatalytic activity of the samples. According to XPS results, (C, N and S) atoms were successfully co-doped into the nanostructures of TH-TiO2 samples. TH-TiO2 samples with thiourea: Ti molar ratio of 1.5 exhibits higher photocatalytic activity than that of the other samples under visible light irradiation, which can be attributed to the synergic effect of the pure anatase structure, the higher light absorption characteristics in visible regions, separation efficiency of electron–hole pairs, the specific surface area and the optimum (C, N and S) content.

Electroless Copper Deposition Using Saccharose Containing Copper Methane Sulphonate Bath with Thiourea as Stabilizer

Electroless copper deposition is used in the fabrication of integrated circuit (IC) interconnections, micro-electro-mechanical systems (MEMS) devices and printed circuit board (PCBs). In order to meet the long term usage of chemical bath for electroless deposition, an eco- friendly copper methane sulphonate (CuMS) was used to prepare the chemical bath for Cu deposit. The deposition parameters such as temperature, pH, Cu ion concentration and para-formaldehyde concentration were optimized at 28 °C with 3 g/L of CuMS, 10 g/L of para-formaldehyde for the pH of 12.75.The deposition rate was increased for high concentration of Cu and para-formaldehyde in the chemical bath. Highly stable bath was achieved at 28 °C with 1 ppm thiourea content and produced uniform Cu film surface with larger grains. Good quality and (200) oriented Cu thin film with larger crystallite size was observed with 1 ppm thiourea added bath.

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

We have developed a methane sulfonic acid (MSA) based ternary electrolytic bath for co-deposition of the eutectic Sn–Ag–Cu films. The bath contains thiourea (TU), which functioned as an effective chelating agent in controlling the bath stability as well as the elemental and microstructural properties of the deposited film. A study of the bath behaviour at TU concentrations in the range 0.06–0.2 M is undertaken with the help of elemental and microstructure analysis, cyclic voltammetry (CV) and impedance analysis. The deposited films have close to eutectic composition with slightly higher Cu content for all the TU concentrations. On the other hand, the microstructure is found to be increasingly refined with increasing TU content. The CV and impedance analysis confirm chelation of Ag and Cu with TU and absence of such chelation with Sn ions. It also indicates close deposition potentials for each metal ion. Impedance analysis specifically reveals presence of an adsorbed insulating film on cathode surface, contributed by MSA or water. It also reveals competitive deposition between the insulating film and metal ions.

Synthesis of Tungsten Oxide Powders Via Thiourea‐Assisted Route: Tailoring from Hierarchical Microspheres to Mesoporously Structured Nanoparticles

Tungsten oxide powders with controlled micro‐to‐nanoscale features, i.e. from microspheres to mesoporous structure, have been synthesized using peroxopolytungstic acid (PTA) and thiourea. Using PTA alone, elliptical tungsten oxide microspindles are hierarchically assembled from rectangular nanoparticles (NPs) after heat treatment at 450°C. With an appropriate addition of thiourea into the PTA precursor, hierarchical microspheres are obtained through the aggregation of isotropic NP unit blocks. When the thiourea content in the precursor increases further, high‐surface‐area mesoporous tungsten oxides composed of well‐dispersed isotropic NPs can be synthesized. We suggest that thiourea acts as a capping agent for forming the isotropic NP unit blocks in the precursors. Moreover, gaseous species released at high temperatures through decomposition and oxidation of nonchelated thiourea in the precursor will suppress the aggregation of NP unit blocks. As a result, tungsten oxide powders in form of microspheres or mesoporous nanostructures can be tailored by the thiourea content in the precursor.

Influence of bath temperature and bath composition on Co–Ag electrodeposition

A study of the best conditions to prepare smooth heterogeneous Co–Ag films with low amounts of S from a thiourea-based electrolytic bath has been performed. Using a 0.01 M AgClO 4 + 0.1 M Co(ClO 4) 2 + 0.1 M thiourea + 0.1 M sodium gluconate + 0.3 M H 3BO 3 + 0.1 M NaClO 4 bath, low temperature (10 °C) allowed obtaining compact and smooth deposits containing 2 wt.% sulphur. Decreasing thiourea content 0.06 M and increasing gluconate concentration up to 0.3 M, better deposits (more compact with lower sulphur content (1.2 wt.%)) were obtained. A clear influence of the species present in the bath on the film quality was observed: while gluconate favoured film cohesion, boric acid hindered hydrogen adsorption. For all films, fcc-Ag, hcp-Co and hcp-CoAg 3 phases were always detected by XRD, TEM and electron diffraction, their proportions varying with the electrodeposition conditions. Magnetic measurements revealed that the increase in the CoAg 3 led to an increase in the film coercivity. GMR values were only measured at cryogenic temperatures, they being higher for the deposits with the lowest sulphur content revealing that sulphur exerts a negative effect on magnetoresistance.

Effect of Thiourea on the Kinetics of the Hydrogen Evolution Reaction at Iron and the Transport of Hydrogen through a Steel Membrane in Solutions of C2H4(OH)2-H2O-HCl

The effect of thiourea (0.5–10 mM) on the kinetics of the hydrogen evolution reaction (HER) at iron and the hydrogen transport through a steel membrane out of ethylene glycol (containing 2 and 10 wt % H2O) and aqueous solutions containing HCl (0.1–0.99 M) with a constant ionic strength equal to unity is studied in parallel experiments. The presence of 0.5 mM of thiourea in the solutions raises the overvoltage of hydrogen evolution, while a subsequent increase in its concentration does not effect the HER kinetics. The dependence of the flux of hydrogen diffusion through the membrane on the thiourea content passes through a maximum.

The annealing behavior of copper deposit electroplated in sulfuric acid bath with various concentrations of thiourea

Abstract The annealing behavior of electroplated copper deposits is reported in this study. The copper deposits were electroplated with a current density of 0.7 A/cm 2 at 53 °C in a sulfuric acid bath containing various concentrations of thiourea. The hardness values of the copper deposits were measured before and after annealing, and the differential scanning calorimetry (DSC) diagrams of the as-electroplated copper deposits were recorded. An improvement of the softening resistance of the copper deposits was observed when the bath contained thiourea ≥3 mg/L. By adding thiourea in the plating bath, smaller grain size of the copper deposits can be achieved. As thiourea content increased ≥3 mg/L, the twin boundary of the copper deposits was significantly increased, and many sulfur-rich particles were deposited along the grain boundaries and a few within the grains of the deposit. These sulfur-rich particles are capable of impeding migration of the grain boundaries and improving the softening resistance of the copper deposits during annealing. The aforementioned microstructures of the copper deposits were examined with transmission electron microscope (TEM) integrated with energy-dispersive X-ray spectrometer (EDX) for chemical composition analysis.

Properties of Ni?S x electrodes for hydrogen evolution from alkaline medium

Active layers for hydrogen evolution were prepared electrolytically from nickel-plating baths containing various amounts of thiourea. The sulphur content of the deposited layers, which is dependent on the thiourea content of the electroplating bath, ranged between 10 and 20 wt%. X-ray photoelectron spectroscopic (XPS) analysis revealed that sulphur was present in the layers not only in the form of sulphide, but also in the forms of thiourea and sulphate entrained from the nickel-plating bath. X-ray diffraction analysis showed that the coatings were poorly crystalline. Nickel sulphide, which produces an X-ray diffraction pattern, was present only in coatings deposited from baths with higher amounts of thiourea. The surface layers of such coatings contained a maximum of 10 at % nickel in the form of Ni3S2. When the Ni−Sx electrodes were under load in 1m KOH over a long period, the hydrogen overpotential was found to vary with time. On the basis of XPS measurements, the initial decrease in hydrogen overpotential was ascribed to the washing-out of adsorbed residues of thiourea. The subsequent increase in the overpotential was due to the deposition of iron on to the surface of the layers from the electrolyte used.