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Thiourea-assisted coating of dispersed copper electrocatalysts on Si photocathodes for solar hydrogen production
摘要： Photoelectrochemical water splitting can convert solar energy into clean hydrogen energy for storage. It is desirable to explore non-precious electrocatalysts for practical applications of a photoelectrode in a large scale. Here, we developed a facile spin-coating and in-situ photoelectrochemical reduction method to prepare a dispersed Cu electrocatalyst on a Si photocathode, which improves the performance remarkably. We find that thiourea in the precursor solution for spin-coating plays an important role in obtaining dispersed Cu particles on the surface of a Si photoelectrode. With thiourea in the precursor, the Cu/Si photocathode shows higher performance than the one without thiourea. Moreover, the Cu/Si photocathode also indicates good stability after 16 h illumination.
关键词： In-situ photoelectrochemical reduction,Cu electrocatalyst,Thiourea,Hydrogen evolution reaction
更新于2025-11-19 16:51:07
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Determination of Thiourea by On–Off Fluorescence Using Nitrogen-Doped Graphene Quantum Dots
摘要： A thiourea-detecting fluorescence sensor with Hg2t as a switch was developed using nitrogen-doped graphene quantum dots (N-GQDs). The surface of N-GQDs had many organic functional groups on which Hg2t was effectively bound and turned off the fluorescence of the N-GQDs. The fluorescence of N-GQDs was turned on by the thiol functional group of thiourea that bound strongly with Hg2t and formed Hg2t/thiourea complexes. After constructing the sensor, the experimental conditions and parameters, such as the pH and Hg2t concentration, were investigated and optimized. Under the optimum conditions, the constructed fluorescence sensor showed high sensitivity to thiourea at concentrations from 0.5 to 14 mM with a low detection limit of 41.7 nM. The sensor also exhibited high specificity, excellent stability, and good reproducibility so that the determination of thiourea in various samples had acceptable values with good recoveries from 99% to 106%. The relative standard deviation was less than 4.1% (n ? 3).
关键词： thiourea,Fluorescence,nitrogen-doped graphene quantum dots (N-GQDs),Hg2t,sensor
更新于2025-11-14 17:04:02
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Ultrathin and Isotropic Metal Sulfide Wrapping on Plasmonic Metal Nanoparticles for SERS-based Detection of Trace Heavy Metal Ions.
摘要： A facile and general strategy is presented for homogenous and ultrathin metal sulfide-wrapping on plasmonic metal (PM) nanoparticles (NPs) based on a thiourea-induced isotropic shell growth. This strategy is typically implemented just via adding the thiourea into pre-formed PM colloidal solutions containing target metal ions. The validity of this strategy is demonstrated by taking the wrapped NPs with Au core and CuS shell or Au@CuS NPs as an example. They are successfully fabricated via adding the thiourea and Cu2+ solutions into pre-formed Au NP colloidal solution. The CuS shell layer is highly homogenous (<10% in relative standard deviation of shell thickness), regardless of the NPs’ shape or curvature. The shell thickness can be controlled from tens down to 0.5 nm just by the addition amounts of the shell precursors. The formation of the shell layer on the Au NPs can be attributed to the alternative deposition of Cu2+ and S2- ions on the thiourea-modified surface of Au NPs in the solution, which induces the isotropic shell growth. Further, this strategy is of good universality. Many other sulfide-wrapped PM NPs, such as Ag@CuS, Au@PtS2, Au@HgS, Ag@Ag2S NPs and Ag@CuS nanorods have been successfully obtained with homogeneous and ultrathin shells. Importantly, such ultrathin sulfide-wrapped PM NPs can be used for SERS-based detection of trace heavy metal ions with strong anti-interference via ion exchange process between the metal sulfide shell and heavy metal ions. This study provides a simple and controllable route for wrapping the homogenous and ultrathin sulfide layers on the PM NPs, and such wrapped NPs have good practical applications in the SERS-based detection of trace heavy metal ions.
关键词： Plasmonic metal nanoparticles,Trace heavy metal ions,Ultrathin sulfide wrapping,Thiourea-induced isotropic shell growth,SERS-based detection
更新于2025-11-14 17:04:02
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Tailoring Shape and Crystallographic Phase of Copper Sulfide Nanostructures Using Novel Thiourea Complexes as Single Source Precursors
摘要： Copper sulfide thin films and nanoparticles have been prepared via aerosol assisted chemical vapour deposition and solvothermal hot injection routes, respectively. Both routes employed heterocyclic amine based benzoylthioureato-copper(II) complexes as single source precursors. Copper sulfide thin films of diverse morphologies ranging from cubic to snowy or irregular crystallites depending on the deposition temperature were observed. Powder X-ray diffraction studies of the as deposited thin films have indicated the formation of hexagonal and cubic phases of copper sulfide. In the case of the nanoparticles, Roxbyite (Cu1.75S) phase was obtained in dodecanethiol at temperatures of 150, 190 and 230 °C. However, a preferred growth of nanoparticles was observed in the presence of oleylamine whereas the roxbyite phase was obtained at temperatures of 150, 200 and 250 °C. Also transmission electron microscopy showed the formation of close to spherical, hexagonal nano-disk and rod shaped nanoparticles.
关键词： Aerosol assisted chemical vapour deposition,Nanoparticles,Heterocyclic thiourea,Copper sulfide,Thermolysis,Thin films
更新于2025-09-23 15:23:52
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Consecutive Interfacial Transformation of Cesium Lead Halide Nanocubes to Ultrathin Nanowires with Improved Stability
摘要： Although all-inorganic CsPbX3 (X=Cl, Br, I) nanocrystals (NCs) have been considered as a promising material for photoelectronic devices, their applications are still limited because of their poor stability and the lack of in-depth understanding. Here, we demonstrate a post-treatment method for the preparation of ultrathin CsPbX3 nanowires (NWs) by treating CsPbBr3 nanocubes with thiourea solution. A systematic study showed a consecutively interfacial transformation process, in which CsPbBr3 nanocubes were first converted to Cs4PbBr6 NCs in the presence of thiourea, followed by a further transformation to CsPbBr3 NCs through an interfacial CsX-stripping process. To reduce the surface energy, an oriented attachment process has been realized and CsPbBr3 NCs aggregated to form ultrathin NWs. The ultrathin CsPbBr3 NWs exhibited high photoluminescence quantum yield (PLQY, up to 60%) and high resistance to water treatment, which can be attributed to the surface passivation by thiourea. In addition to thiourea, cysteine and thioacetamide that contain thiol group can also be used to trigger this transformation. This work can not only offer a facile method for the synthesis of efficient and stable ultrathin CsPbBr3 NWs, but also help to reveal the in-depth mechanisms which may be very useful in the field of metal halide perovskite NCs.
关键词： ultrathin nanowires,oriented attachment,Cs4PbBr6,CsPbBr3,thiourea
更新于2025-09-23 15:23:52
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A Green and Facile Synthesis for rGO/Ag Nanocomposites Using One-step Chemical Co-reduction Route at Ambient Temperature and Combined First Principles Theoretical Analyze
摘要： Recently, graphene decorated with various inorganic nanoparticles, such as Pt, Au, Ag, TiO2 and Fe3O4, among which Ag nanocomposites are good candidates for electronics, optics, electrochemistry and catalysis. However, preparation techniques for Ag nanoparticles/carbon matrix hybrids require tedious multi-step processes often involving toxic reducing agents / high temperatures which is not viable for scalable production. Here, a facile, one step and eco-friendly chemical co-reduction route was utilized to synthesis of a new nanocomposites by Ag nanoparticle anchored on reduced graphene oxide (rGO) at ambient temperature and combined first principles theoretical analyze their interfacial adsorption behavior, is reported. In this way, graphene oxide (GO) and Ag+ simultaneously reduced by thiourea dioxide (TD) without using any additional reduced reactants. Results indicated that GO was successfully reduced to rGO and well-dispersed Ag nanoparticles with sizes of 6~7 nm, anchored on the surface of rGO sheets. Reduction mechanism was attributed to the synergistic effect of its hydrolysis products in aqueous media. The experiment and theoretical calculation results obtained demonstrate this method to be applicable to the synthesis of other metals on rGO sheets in order to improve wettability and interfacial bonding between rGO and metal and may possibly find various forthcoming medicinal, industrial and technological applications.
关键词： In-stiu co-reduction,Green reduce graphene/Ag nanocomposites,Interfacial behavior,First principles,Thiourea dioxide
更新于2025-09-23 15:23:52
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Improvement of Cu(In,Ga)Se <sub/>2</sub> solar cell performance by thiourea treatment
摘要： 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.
关键词： thiourea treatment,solar cell,Cu(In,Ga)Se2,carrier recombination,film quality
更新于2025-09-23 15:21:01
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Determination of BCM-7 based on an ultrasensitive aptasensor fabricated of gold nanoparticles and ZnS quantum dots
摘要： In this study, an ultrasensitive electrochemical aptasensor for the determination of the β-casomorphin 7 (BCM-7) as a promising biomarker of autism disorder is introduced. According to the proposed strategy, a glassy carbon electrode (GCE) was modi?ed by thiourea capped-ZnS QDs (ZnS-QDs) and gold nanoparticles (AuNPs) to further immobilization the amino-aptamer (NH2-Apt) on its surface. The NH2-Apt as a receptor of the BCM-7 was attached to the embedded surface via a formation of the Au–N bonds between the AuNPs and amino groups of the Apt. The evaluation of aptasensor by various electrochemical techniques exhibited successful sensing of the BCM-7 under two broad linear concentration ranges from 1 fM to 0.6 μM with a limit of detection (LOD) down to 350 aM. Also, the performance of the aptasensor in BCM-7 detection in real human urine samples was satisfactorily investigated. These ?ndings may facilitate distinguish of this challenging disorder and help human health.
关键词： Thiourea capped-ZnS QDs,β-casomorphin 7,Glassy carbon electrode,Gold nanoparticles,Aptasensor,Autism
更新于2025-09-23 15:21:01
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Poly(ethylene glycol)a??poly(propylene glycol)a??poly(ethylene glycol) and polyvinylidene fluoride blend doped with oxydianiline-based thiourea derivatives as a novel and modest gel electrolyte system for dye-sensitized solar cell applications
摘要： Unique symmetrical thiourea derivatives with an oxydianiline core were synthesized using cost-effective and simple methods. A new gel electrolyte system was prepared using these thiourea additives along with a highly conductive PEG–PPG–PEG block copolymer, PVDF, and an iodide/triiodide redox couple. The PEG units present in the electrolyte are well-known for their intense segmental motion of ions, which can degrade the recombination rate and favour the charge transfer. The thiourea additives interacted well with the redox couple to limit iodine sublimation and their adsorption induced a negative potential shift for TiO2. The highest efficiency attained by utilizing such gel polymer electrolytes was 5.75%, especially with 1,10-(oxybis(4,1-phenylene))bis(3-(6-methylpyridin-2-yl) thiourea) (OPPT), under an irradiation of 100 mW cm?2. The electrochemical impedance spectroscopy, UV-vis absorption spectroscopy, differential scanning calorimetry, and FTIR spectroscopy data of such gel polymer electrolytes favoured the PCE order of the additives used in DSSCs. The improvement in the DSSC performance with symmetrical thioureas having electron-rich atoms was practically attributed to the reduction of back electron transfer, dye regeneration, and hole transport.
关键词： Poly(ethylene glycol),poly(ethylene glycol),dye-sensitized solar cell,polyvinylidene fluoride,poly(propylene glycol),oxydianiline-based thiourea derivatives,gel electrolyte system
更新于2025-09-23 15:19:57
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Growth, Thermal and Spectroscopic Studies of Bis-thiourea Nickel Barium Chloride Single Crystals
摘要： Bis-thiourea nickel barium chloride was synthesized and crystals were grown by slow aqueous solvent evaporation technique. The powder XRD analysis of grown crystal was suggested to have orthorhombic crystal structure. The unit cell parameters of grown crystal as: a = 9.70 ?, b = 10.68 ? and c = 17.95 ?. The contents of nickel and barium in the grown crystals was analyzed using EDAX. The presence of various functional groups was confirmed by FTIR spectroscopy studies. From the UV-visible spectrum, the material has about 90 % optical transparency in the entire visible region. From the thermogravimetric analysis, it was found that the crystals remained stable up to 170 oC. The endothermic reactions were identified from the differential thermal analysis.
关键词： Crystal growth,Slow evaporation technique,Bis-thiourea nickel barium chloride,Powder X-ray diffraction
更新于2025-09-19 17:15:36