Thiourea Treatment Research Articles

Formation of CZTSSe absorber layer using thiourea treatment of CZTSe

In the present work, CZTSe (Cu 2 ZnSnSe 4 ) films were deposited by Thermal evaporation technique. The as deposited films were annealed at 450 °C for 10 min. To incorporate Sulfur in the CZTSe film and to replace some of the Se by S, the films (as deposited and annealed) were treated with Thiourea solution (1 Molar). Further the films were annealed at 450 °C for 10 min after the thiourea treatment. Finally the films were characterized for phase analysis using XRD and Raman. The composition analysis was done using EDXRF. The band gap of the film varies according to the S/Se ratio. Compositional analysis as obtained from ED-XRF, shows the required ratio of Cu/(Zn + Sn) < 1 and Zn/Sn > 1 for all the films. The conductivity and mobility of the films changes with variation in sulfur and selenium ratio. The obtained electrical and optical properties of CZTSe absorber layer after thiourea treatment are suitable for device application .

Facile preparation of nitrogen and FeSx codoped porous carbon with high catalytic activity under alkaline condition

In this work, we reported the preparation of nitrogen and FeSx codoped porous carbon through hydrothermal treatment of FeCl3, thiourea and porous carbon. The degradation results demonstrated that PC-FeSx composite displayed high degradation efficiency towards organic dyes with excellent reusability. Moreover, the degradation efficiency under alkaline solution (pH = 11) is even better under acidic solution (pH = 3), indicating that other routes for generation free radicals were existed. Electron spin resonance (ESR) spin−trap technique was used to determine the free radical species and results demonstrated that both •OH and O2− are formed during Fenton reaction. Considered the facile operation procedure, low cost of reagents and high degradation efficiency, we believe this work should of broad interest for fabrication of multifunctional composites for environmental treatment.

Improvement of Cu(In,Ga)Se2 solar cell performance by thiourea treatment

We investigated the effects of a thiourea treatment performed to the absorber of Cu(In,Ga)Se2 (CIGS) solar cells. The thiourea treatment successfully improved the open-circuit voltage, fill factor, and conversion efficiency of the solar cells. Reduced ideality factor and reverse saturation current density demonstrated that the suppression of carrier recombination contributed to the improvement in solar cell performance. Increased intensity in cross-sectional electron-beam-induced current measurements confirmed the improved film quality with the thiourea treatment. Additionally, an enhanced carrier density observed with the treatment suggests the passivation of donor-type defects. These results indicate that the thiourea treatment is promising to improve the absorber quality and enhance the performance of CIGS solar cells.

Design of Red Emissive Carbon Dots: Robust Performance for Analytical Applications in Pesticide Monitoring.

Synthesis of red emissive carbon dots (CDs) is highly desirable for sensing applications, as they still remain as bottlenecks in terms of precursor synthesis and product purification. Herein, we have designed a new strategy for realizing efficient red emissive CD optimal emission at 610 nm (fluorescence quantum yield ca. 24.0%) based on solvothermal treatment of citric acid and thiourea using dimethylformamide as solvent. Further investigations reveal that the conjugating sp2-domain controlling the incorporation of nitrogen and surface engineering are mainly responsible for the obtained red emission of CDs. Taking advantage of optical properties and abundant surface functional groups, CDs were considered to facilely construct a ratiometric fluorescent platform for quantifying trace levels of organophosphorus pesticides (OPs). Combining the acetylcholinesterase-mediated polymerization of dopamine and the inhibition of pesticide toward the enzyme, the degree of polymerization of dopamine rationally depends on the concentration of OPs. By measuring the fluorescence intensity ratio, the proposed platform exhibited highly selective and robust performance toward OPs, displaying ultrasensitive recognition in the pg L-1 level. The multiexcitation format could efficiently shield background interference from complex samples by introducing a self-calibrated reference signal, which affords accurate and reliable quantitative information, endowing CDs as a universal candidate for a biosensing application by combining target-specific recognition elements.

The role of miR-92 in regulating early development and metamorphosis of Japanese flounder Paralichthys olivaceus.

MicroRNAs are a class of short non-coding RNAs that contain approximately 22 nucleotides and play a regulatory role in RNA silencing and translational repression. miR-92 belongs to the miR-17-92 family and has a regulatory effect on cell proliferation, apoptosis, and expression of proto-oncogenes and tumor suppressor genes. However, its function in flatfish is unclear. In this study, we used farmed Japanese flounder, Paralichthys olivaceus, and showed that gata5 is a target gene of miR-92. Experiments on miR-92 overexpression indicated that gata5 and sox17 were downregulated, while the transcription level of ntl increased. By contrast, depletion of miR-92 resulted in increased gata5 and sox17 levels and reduced ntl level. Moreover, thiourea treatment indicated that miR-92 may inhibit the metamorphic development of Japanese flounder. Our study suggests that miR-92 regulates the fate of endoderm and mesoderm by controlling gata5.

A facile one step hydrothermal synthesis of carbon quantum dots for label -free fluorescence sensing approach to detect picric acid in aqueous solution

In this work, a facile one step approach has been applied for the synthesis of nitrogen and sulphur co-doped water soluble carbon quantum dots (NS-CQDs) through hydrothermal treatment of L-Lysine and thiourea. The obtained NS-CQDs have a high quantum yield (QY) of 53.19 % and emit strong blue fluorescence under UV light excitation of wavelength 365 nm. The morphology of NS-CQDs is spherical in shape and their sizes are distributed in the range 5–8 nm with average diameter 6.86 nm. Moreover the NS-CQDs show excitation dependent emission behavior due to quantum confinement effect. Additionally, NS-CQDs serve as a fluorescent probe for the selective and sensitive detection of picric acid (PA) in aqueous solution. A good linear response to PA in the concentration range 1–10 μM with a detection limit 0.24 μM has been obtained. The high selectivity of PA by NS-CQDs is suggested to arise from fluorescence resonance energy transfer (FRET) mechanism. Finally these NS-CQDs fluorescent probes have been examined in real water sample by measuring the concentration of PA in tap water.

The impact of Thiourea on Tea (Camellia sinensis) callus proliferation and secondary metabolites content

In the present experiment, the in vitro callus production from tea leaf explants was induced on three different basal media. Then, the efficiency of tea callus proliferation was enhanced through application of thiourea to the proliferation medium. Furthermore, the caffeine and Epigallocatechin Gallate content of the callus and leaf tissues were estimated through HPLC method. The calli mass volume in WPM (woody plant medium) supplemented with thiourea (either 0.1 or 1.0 mM) was significantly higher than other basal media. The callus tissue collected from media enriched with thiourea had significantly more caffeine content but the level of Epigallocatechin Gallate was not statistically affected by thiourea treatments. The amount of these two compounds was also estimated in young and old leaves of the tea mother plants and it was found that the callus tissue had little amount of caffeine and Epigallocatechin Gallate as compared to maternal tissues. It is concluded that, in species with low rate callus proliferation, addition of thiourea to the medium may be followed as an effective and low cost option for callus proliferation improvement.

A direct one-step synthesis of ultrathin g-C3N4 nanosheets from thiourea for boosting solar photocatalytic H2 evolution

Two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets, as the promising photocatalyst with fascinating properties, have become a “rising star” in the field of photocatalysis. Although g-C3N4 nanosheets exfoliated from the bulk g-C3N4 powders are extensively emerged, developing a simple synthetic approach is still full of challenge. To this end, here we report a direct polymerization strategy to fabricate the ultrathin g-C3N4 nanosheets, that is only heating treatment of thiourea in air without addition of any template. The photocatalytic activities of as-prepared samples were evaluated by photoreduction of water to hydrogen (H2) using triethanolamine as sacrificial agent and Pt as co-catalyst under visible-light irradiation (λ > 420 nm). As a result, our few-layered g-C3N4 nanosheets with an average thickness of 3.5 nm exhibit a superior visible-light photocatalytic H2 evolution rate (HER) of 1391 μmol g−1 h−1 and a remarkable apparent quantum efficiency of 6.6% at 420 nm. Eventually, the HER of as-fabricated ultrathin g-C3N4 nanosheets is not only much higher than the dicyandiamide-derived g-C3N4 or melamine-derived g-C3N4, but also greater than the thermal-oxidation etched g-C3N4 nanosheets under the same condition.

Thiourea-mediated Nitric Oxide Production Enhances Tolerance to Boron Toxicity by Reducing Oxidative Stress in Bread Wheat (Triticum aestivum L.) and Durum Wheat (Triticum durum Desf.) Plants

Two independent experiments were performed to assess the role of thiourea (TU)-mediated nitric oxide (NO) in mitigating boron toxicity (BT) in bread wheat (Triticum aestivum L. cv. Pandas) and durum wheat (Triticum durum cv. Altintoprak 98) plants. In the first experiment, plants of the two wheat species were grown under control (0.05 mM B) and BT (0.2 mM B) supplied to nutrient solution for 4 weeks after germination. These two treatments were also combined with TU spray at 200 or 400 mg L−1 once a week during the period of stress. Boron toxicity reduced dry weights of shoot and root, leaf total chlorophyll, efficiency of photosystem II (Fv/Fm) and leaf relative water content, whereas it increased endogenous nitric oxide (NO), nitric oxide synthase (NOS), electrolyte leakage (EL), hydrogen peroxide (H2O2), malondialdehyde (MDA) and leaf B content. Reductions in total dry matter were 33% and 61% of control in cvs. Pandas and Altintoprak, respectively. Exogenous application of TU improved the plant growth attributes and led to further increases in NO in the leaves. An additional experiment was set up to further understand whether or not TU mediated NO production played a significant role in mitigation of BT using 0.1 mM scavenger of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO) combined with the TU treatments by spraying once a week for 4 weeks. TU-induced BT tolerance was totally eliminated by cPTIO by reversing endogenous NO levels. BT enhanced the activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC. 1.11.1.6), peroxidase (POD; EC. 1.11.1.7) and lipoxygenase (LOX; EC. 1.12.11.12) as well as the contents of soluble sugars (SS), soluble proteins and phenols, but decreased NR. TU treatments enhanced enzyme activities, but reduced contents of soluble sugars (SS), soluble protein and phenols. The present results clearly indicate that TU mediated endogenous NO significantly improved BT tolerance of wheat plants. This evidence was also supported by the increase in hydrogen peroxide (H2O2) and malondialdehyde (MDA) as well as plant growth inhibition with the application of TU combined with cPTIO.

Thiourea Interfacial Modification for Highly Efficient Planar Perovskite Solar Cells

Interfacial engineering is an efficient strategy for enhancing the performance of perovskite photovoltaic cells. Here, we present a novel method to modify the surface of TiO2 with thiourea. X-ray photoelectron spectroscopy indicates that thiourea treatment inactivates the TiO2 surface groups. Kelvin probe force microscopy and ultraviolet photoelectron spectra demonstrate an energy level downshift of the modified TiO2. Photoluminescence spectra reveal the reduced interface charge recombination and an improved charge transportation/extraction. Tafel and Nyquist plots elucidate a decrease of trap-state density and an increase of conductivity of the modified TiO2. Hence, the planar perovskite solar cell based on the TiO2 electron transport layer (ETL) modified with 0.1 M thiourea yields an efficiency of 19.18%, which is 7.5% larger than that of the device based on the pristine TiO2 ETL. The simple procedure and the significant performance improvement render this method promising.

Effect of Thiourea on Physiological Performance of Two Salt Affected Rice (Oryza sativa L.) Cultivars

Aims: The aim of the experiment was to investigate the effect of thiourea on physiological characteristics of two rice (Oryza sativa L.) varieties under impact of salinity. Study Design: Experiment includes two rice varieties named as B-515 and KS-282, salinity level of 150 mM, thiourea of 0.25 mM alone and in combination were arranged in a completely randomized design (CRD). Place and Duration of Study: Old Botanical Garden, University of Agriculture Faisalabad, Pakistan, between 4th July and 21st August 2015. Methodology: Transplants of two rice varieties, Basmati-515 and KS-282 were exposed to salinity (150 mM) and thiourea (0.25 mM) after one month of transplanting in a Completely Randomized Design with three replications. Harvesting data was taken that include fresh and dry weights, leaf area, number of tillers, photosynthetic pigments, photosynthetic rate, transpiration rate, stomatal and substomatal conductance, water use efficiency and intrinsic CO2 concentration as well as chlorophyll contents in two rice varieties. Results: Thiourea treatment enhanced photosynthetic efficiency of Basmati-515 more than KS-282 by improving the chlorophyll and carotenoid contents and gas exchange attributes more than control. Conclusion: Salinity profoundly affect the physiological performance of two rice varieties especially that of KS-282, while 0.25 mM thiourea application unable to mitigate the effect of salinity but thiourea alone proved to be beneficial for both the rice varieties.

Facile microwave assisted synthesis of N-rich carbon quantum dots/dual-phase TiO2 heterostructured nanocomposites with high activity in CO2 photoreduction

In this work, several efficient heterostructured nanocomposites with enhanced CO2 photoreduction activity were successfully constructed by anchoring carbon quantum dots onto TiO2 using a facile microwave assisted synthesis strategy. The carbon quantum dots obtained by microwave treatment of thiourea and citric acid acted as a sensitizer in the composites to enhance light absorption. The high-resolution transmission electron microscopy (HR-TEM) revealed that a closely integrated interface between carbon quantum dots and TiO2 nanosheets was formed in the heterostructured nanocomposites. Furthermore, the photogenerated charge transfer and separation in the heterogeneous nanocomposites were demonstrated to be significantly improved when compared with that in pristine TiO2. Consequently, a remarkable enhancement of photocatalytic activity evaluated for CO2 photoreduction under simulated solar light irradiation can be found in the nanocomposites. Maximum CH4 and CO yields of 0.769 and 1.153 μmol, respectively, have been obtained from the photoreduction after one hour irradiation without any noble metal loaded on photocatalyst. The amounts of CH4 and CO generated over nanocoposite are 7.79 and 7.61 times as high as those on pristine TiO2. This encouraging performance in CO2 photoreduction shows that these nanocomposites might be a prospective material in environmental protection and energy conversion.

Effect of dormancy breaking chemicals on microtuber production potential under in vivo conditions of central India

The present study was carried out at ICAR -Central Potato Research Station, Gwalior during 2012-13 to assess the effect of dormancy breaking chemicals, their dip duration and microtuber size on growth and yield parameters. The three different size &gt;4-6mm, &gt;6-8mm and &gt;8mm of variety Kufri Sindhuri were given dip treatment with six types of growth regulators/ dormancy breaking chemicals viz 1ppm gibberelic acid, 0.5 ppm gibberllic acid, 1% thiourea, 0.5 % thiourea, 1ppm gibberllic acid + 1% thiourea and 0.5 ppm gibberllic acid + 0.5 % thiourea along with water control for 30 min, 45 min and 60 min. All the treatments exhibited better growth and yield parameters over water control but significantly best at 5% was 0.5 ppm gibberllic acid treatment for growth parameters and 0.5 ppm gibberllic acid + 0.5 % thiourea treatment for yield parameters. All the dip duration 30 min, 45 min and 60 min had not significant at 5% level effect for both growth and yield parameters. The larger sized micro-tuber (&gt;8 mm) showed significantly superior plant emergence, plant height, number of compound leaves per plant, number of stems per plant both at 50 and 75 days after planting followed by 4-8 mm grade and &lt;4 mm grade micro-tubers. Similar trend was observed for all the yield parameters. The overall mean finding indicates that micro-tubers treated with 0.5 ppm gibberllic acid in combination with 0.5 % thiourea gave highest yield (226.0 q/ha tuber), among micro-tuber size of &gt;8mm (295.0 q/ha tuber) and among dip duration 30 min (206.67q/ha) and 45 min (210 q/ha) resulted in significantly higher yield parameters under nucleus seed production in in vivo conditions of central India.

Single atom (K/Na) doped graphitic carbon Nitride@MnO2 as an efficient electrode Material for supercapacitor

Vertically assembled two-dimentional materials have great scientific and technological promise. In this work, altrathin atom doped graphitic carbon nitride (g-C3N4) was synthesised via thermal treatment of thiourea and KBr/NaBr. Free-standing manganese dioxide nanoflakes were uniformly grown on K/Na doped g-C3N4 through hydrothermal reaction. The K doped g-C3N4@ MnO2 has a specific capacitance twice higher than that of pure g-C3N4@ MnO2. This unique design brought excellent specific capacitance (375Fg−1) and cycle stability, which showed that atom doping is an effective approach to enhance electrochemical performance. In addition, the low cost, facial synthesis and small amount of addings make this strategy an optimized approach to construct g-C3N4 based electrode materials.

Enhancement of structural &amp; opt- electronic properties of vacuum processed Cu2ZnSnS4 thin film by thiourea treatment

Abstract In the present work, Cu-Zn-Sn-S precursor films were deposited by co-evaporation using elemental precursors. Prior to sulfurization, the precursor films were divided into three sets. Set1- Cu-Zn-Sn-S precursor directly sulfurized without any pre treatment, Set 2- Cu-Zn-Sn-S precursor film with an additional SnS layer deposited by thermal evaporation & sulfurized & Set 3 Precursor Cu-Zn-Sn-S film was treated with thiourea solution before sulfurization. From combined X-ray diffraction and Raman scattering analysis, CZTS phase formation was revealed for all three sets. Set 1 & Set 2 CZTS films exhibited SnS and CuS compounds as secondary phases while the set 3 film was found to have pure kesterite phase. Highly compact and uniform films were formed for all the three CZTS sets. Compositional analysis showed that the CZTS-TU film exhibit Cu-poor and Zn rich ratios while the rest two films showed slight deviations from ideal values. By employing glancing angle XRD technique, penetration depth values were calculated at four different incident angles. Phase, crystalline nature and micro structural parameters were evaluated for CZTS films at various incident angles. Best crystalline structure, morphology, compositions was obtained for the thiourea treated CZTS film.

Oxidative Cleavage of C=S and P=S Bonds at an AlI Center: Preparation of Terminally Bound Aluminum Sulfides.

The treatment of cyclic thioureas with the aluminum(I) compound NacNacAl (1; NacNac=[ArNC(Me)CHC(Me)NAr]- , Ar=2,6-Pri2 C6 H3 ) resulted in oxidative cleavage of the C=S bond and the formation of 3 and 5, the first monomeric aluminum complexes with an Al=S double bond stabilized by N-heterocyclic carbenes. Compound 1 also reacted with triphenylphosphine sulfide in a similar manner, which resulted in cleavage of the P=S bond and production of the adduct [NacNacAl=S(S=PPh3 )] (8). The Al=S double bond in 3 can react with phenyl isothiocyanate to furnish the cycloaddition product 9 and zwitterion 10 as a result of coupling between the liberated carbene and PhN=C=S. All novel complexes were characterized by multinuclear NMR spectroscopy, and the structures of 5, 9, and 10 were confirmed by X-ray diffraction analysis. The nature of the Al=S bond in 5 was also probed by DFT calculations.

Oxidative Cleavage of C=S and P=S Bonds at an AlI Center: Preparation of Terminally Bound Aluminum Sulfides

AbstractThe treatment of cyclic thioureas with the aluminum(I) compound NacNacAl (1; NacNac=[ArNC(Me)CHC(Me)NAr]−, Ar=2,6‐Pri2C6H3) resulted in oxidative cleavage of the C=S bond and the formation of 3 and 5, the first monomeric aluminum complexes with an Al=S double bond stabilized by N‐heterocyclic carbenes. Compound 1 also reacted with triphenylphosphine sulfide in a similar manner, which resulted in cleavage of the P=S bond and production of the adduct [NacNacAl=S(S=PPh3)] (8). The Al=S double bond in 3 can react with phenyl isothiocyanate to furnish the cycloaddition product 9 and zwitterion 10 as a result of coupling between the liberated carbene and PhN=C=S. All novel complexes were characterized by multinuclear NMR spectroscopy, and the structures of 5, 9, and 10 were confirmed by X‐ray diffraction analysis. The nature of the Al=S bond in 5 was also probed by DFT calculations.

Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells.

Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1−xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber|buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells.

Eco-friendly and rapid microwave synthesis of green fluorescent graphitic carbon nitride quantum dots for vitro bioimaging

Herein, bright green luminescent graphitic carbon nitride quantum dots (GCNQDs) doped with oxygen and sulfur are prepared simply by microwave treatment of citric acid and thiourea. The as-obtained GCNQDs show excitation wavelength and pH dependent luminescence behaviors in the visible range. Besides, the GCNQDs exhibit high fluorescence quantum yield (31.67%), strong resistance to the interference of high ionic strength environment, and good biocompatibility as demonstrated by the cell viability assay. Thus, the resulting GCNQDs can be used as a promising fluorescent probe for HeLa cell imaging with low cytotoxicity, and have great potential in bioanalysis and related fields.

Improvement of Cu2ZnSn(S,Se)4 solar cell efficiency by surface treatment

AbstractSurface treatments for the purpose of contamination elimination and surface passivation were performed to as‐deposited CZTSSe thin films before CdS buffer layer deposition. It was found that HCl etching treatment removes contaminations such as sulfide and oxide on CZTSSe surface and helps enhancement of thiourea treatment carried out after HCl etching. Thiourea treatment drastically improves solar cell characteristics, especially FF and JSC, and it would have the effect of surface passivation, although surface sulfuration does not occur. The improvement of characteristics seems to be due to improvement of the film quality and increase in the width of a depletion layer. As a result, conversion efficiency of CZTSSe solar cells was improved from 6.3% to 10.3% with sequential treatment of HCl etching and thiourea treatment. 10.5% was achieved by air anneal after fabrication with both treatments.