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NaYF4@Yb,Ho,Au/GO-nanohybrid materials for SERS applications –Pb(II) detection and prediction
摘要： Nowadays, nano hybrid materials (NHMs) with latent applications have been employed in different fields, particularly for sensor applications. Among NHMs, GO based - upconversion NHMs system is an emerging area for the rapid detection of different hazardous materials either as an aptamer based or free-labeled sensing techniques. For the detection of Pb(II) in water, NaYF4@Yb,Ho,Au/GO-NaYF4@Yb,Ho,Au NHMs system was developed. The synthesized NHMs were characterized by XRD, FT-IR, SEM with EDS, TEM and Raman characterization techniques for observation and confirmation. NaYF4@Yb,Ho,Au/GO-NaYF4@Yb,Ho,Au NHMs fabricated sensors were observed to detect and quantify on real-time basis Pb(II) via surface-enhanced-Raman spectroscopy within the dynamic linear range of 98 – 99%, with detection limits of 1.16 × 10-9 g/mL and 1.15×10-8 g/mL obtained respectively for NaYF4@Yb,Ho,Au and GO- NaYF4@Yb,Ho,Au NHMs.. The relative standard deviation (RSD) value achieved for both were less than ~10%, indicative of reproducibility in the quantification results for Pb(II) traces in water when combined with genetic algorithm partial least square (GA-PLS). Results suggest that the GO-NHMs better enhanced the SERS Pb (II) vis-à-vis NaYF4@Yb,Ho,Au. The GO-wrapped NHMs exhibited a further better SERS performance because the heterostructure of GO-NHMs could be potentially useful for SERS-based immunoassay due to the much easier charge transfer between graphene and the metal ions and molecules so the homogeneity of the SERS probe was improved simultaneously (chemical enhancement) by GO-NHMs.
关键词： Graphene Oxide (GO),Pb(II),Nano hybrid materials (NHMs),Chemometric algorithms modeling (GAPLS),SERS
更新于2025-09-09 09:28:46
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Polymer morphology and interfacial charge transfer dominate over energy-dependent scattering in organic-inorganic thermoelectrics
摘要： Hybrid (organic-inorganic) materials have emerged as a promising class of thermoelectric materials, achieving power factors (S2σ) exceeding those of either constituent. The mechanism of this enhancement is still under debate, and pinpointing the underlying physics has proven dif?cult. In this work, we combine transport measurements with theoretical simulations and ?rst principles calculations on a prototypical PEDOT:PSS-Te(Cux) nanowire hybrid material system to understand the effect of templating and charge redistribution on the thermoelectric performance. Further, we apply the recently developed Kang-Snyder charge transport model to show that scattering of holes in the hybrid system, de?ned by the energy-dependent scattering parameter, remains the same as in the host polymer matrix; performance is instead dictated by polymer morphology manifested in an energy-independent transport coef?cient. We build upon this language to explain thermoelectric behavior in a variety of PEDOT and P3HT based hybrids acting as a guide for future work in multiphase materials.
关键词： polymer morphology,charge transport,PEDOT:PSS,thermoelectric materials,hybrid materials
更新于2025-09-04 15:30:14
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Designing surface-enhanced Raman scattering (SERS) platforms beyond hotspot engineering: emerging opportunities in analyte manipulations and hybrid materials
摘要： Surface-enhanced Raman scattering (SERS) is a molecule-specific spectroscopic technique with diverse applications in (bio)chemistry, clinical diagnosis and toxin sensing. While hotspot engineering has expedited SERS development, it is still challenging to detect molecules with no specific affinity to plasmonic surfaces. With the aim of improving detection performances, we venture beyond hotspot engineering in this tutorial review and focus on emerging material design strategies to capture and confine analytes near SERS-active surfaces as well as various promising hybrid SERS platforms. We outline five major approaches to enhance SERS performance: (1) enlarging Raman scattering cross-sections of non-resonant molecules via chemical coupling reactions; (2) targeted chemical capturing of analytes through surface-grafted agents to localize them on plasmonic surfaces; (3) physically confining liquid analytes on non-wetting SERS-active surfaces and (4) confining gaseous analytes using porous materials over SERS hotspots; (5) synergizing conventional metal-based SERS platforms with functional materials such as graphene, semiconducting materials, and piezoelectric polymers. These approaches can be integrated with engineered hotspots as a multifaceted strategy to further boost SERS sensitivities that are unachievable using hotspot engineering alone. Finally, we highlight current challenges in this research area and suggest new research directions towards efficient SERS designs critical for real-world applications.
关键词： non-wetting surfaces,porous materials,Surface-enhanced Raman scattering,SERS,plasmonic surfaces,chemical coupling,hotspot engineering,semiconductors,piezoelectric polymers,analyte manipulation,hybrid materials,graphene
更新于2025-09-04 15:30:14
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The structure of PA-Se-S-Cd composite materials probed with FTIR spectroscopy
摘要： Composite organic-inorganic functional materials are of significant importance in various applications of science and technology. In this work, PA-Se-S and PA-Se-S-Cd composite materials obtained by employing the sorption-diffusion method are discussed. A single precursor – K2SeS2O6 – was used as the source of both sulfur and selenium. In the aqueous solution, SeS2O6 2? and its decomposition products diffused into the polymer where they reacted with Cd2+ ions so that to form cadmium chalcogenide particles. Fourier-transform infrared (FTIR) spectroscopy was used to characterize the interactions between polyamide 6 and inorganic constituents, namely, K2SeS2O6, CdS and CdSe. The spectral behavior of amide I, II, A and B bands evidenced the competing formation of complex bonding structures based on the formation of covalent, electrostatic and hydrogen bonding between the PA 6 amide (NHCO) groups and the inorganic constituents. The number and the type of the formed bonds depend on the polyamide 6 exposure time in the K2SeS2O6 precursor solution. Such a complex interaction induces obvious conformational changes of the polyamide 6 chains. A possible bonding mechanism has been proposed to explain the observed spectral phenomena.
关键词： Inorganic-organic hybrid materials,Cadmium chalcogenides,Polyamide 6,Infrared spectra,Potassium selenotrithionate
更新于2025-09-04 15:30:14
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Tailoring the Linear and Second-Order Nonlinear Optical Responses of the Titanium-MIL-125 Metal-Organic Framework through Ligand Functionalization: A First Principles Study
摘要： Density functional theory calculations have been performed to investigate the linear and second order nonlinear optical (NLO) properties of titanium-based MIL-125 metal-organic frameworks in crystalline form, in which the 1,4-benzene-dicarboxylate (BDC) linkers are modified by introducing different functional groups or by extending BDC ligand to contain two (MIL-126) and three (MIL-127) benzene rings. Our results reveal that the functionalization of BDC linker tends to increase the dielectric constants and the magnitude of birefringence of MIL-125, especially for the aminated derivatives. Correspondingly, the incorporation of substituent group will improve the phase matching performance of MIL-125. As for the second harmonic generation (SHG) susceptibility, the SHG activity of the pristine MIL-125 is comparable to KDP, which can be attributed mostly to the contributions of TiO5(OH) octahedra. It is noted that after introducing substituent group into BDC linker, the organic part will have a remarkable influence on the SHG intensity. However, the specific effect on the NLO response is dependent on the type of functional group incorporated into BDC ligand, and only the inclusion of amine group that is strongly electron-donating can obviously enhance the SHG activity of MIL-125. In addition, MIL-126 and MIL-127 with longer aromatic linking unit are not suitable to act as NLO materials due to their poor phase matching abilities, but they are the promising candidates for the low dielectric constant materials. The present study can provide theoretical insights to design new second-order NLO materials based on MIL-125.
关键词： Nonlinear Optical Properties,Density Functional Theory,Hybrid Materials,Ligand Functionalization,Metal-Organic Framework,Plasmonics,Optical,Magnetic
更新于2025-09-04 15:30:14
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Electron/Energy Transfer Studies on Hybrid Materials Based on Dinuclear Coordination Compounds of Twisted Perylene Diimide
摘要： To understand the influence of transition metal ion coordination on the properties and performance of the triads, the symmetric bridging ligand, 1,10-phenanthroline-perylene diimide-1,10-phenanthroline, 1,10-Phen-PDI-1,10-Phen (1) comprising four electron-donating 4-methoxyphenoxy bulky groups at bay-positions and its corresponding square-planar coordination compounds with dichloroplatinum(II), [{PtCl2}2-1] (2) and palladium(II) [{PdCl2}2-1] (3) were prepared in order to tune the photochemical and optical properties of these hybrid materials. These triads show strong electronic absorption bands attributed to the PDI and M(II)(1,10-Phen)Cl2 moieties in DMSO. UV-Vis absorption spectra of compounds were calculated using Time-Dependent Density Functional Theory (TDDFT) for the ground state optimized structures in DCM. Current results indicate that 2 has the lowest HOMO-LUMO gap (2.29 eV in DCM) among the investigated molecules. The energy and charge transfer processes with tailoring molecular structures are one of the important strategies for the design of future functional triads based on donor and acceptor moieties for hybrids optoelectronic devices. Thus, we studied linear absorption, fluorescence, and ultrafast transient absorption spectra measurements for the triads in dichloromethane to investigate the impact of different functionalization strategies on the optical characteristics, photo-stability, and photo-induced charge-transfer (CT) processes. The observed ultrafast intramolecular charge transfer from donor units to acceptor part of 1, 2 and 3 is related to fluorescence quenching and faster singlet state decay on transient absorption measurements. The intramolecular charge transfer mechanism was also compared with the unsymmetrical counterparts that were investigated previously. Symmetrical compounds exhibit faster charge transfer in comparison with the unsymmetrical compounds.
关键词： density functional theory,coordination compounds,ultrafast pump-probe,Perylene diimide,hybrid materials
更新于2025-09-04 15:30:14
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A Study on the Weak Ferromagnetism of Nanocrystalline Stannous Oxide Induced by L-Shaped O-Sn-O Vacancies
摘要： Nanocrystalline stannous oxide (SnO) powder has been prepared by ball-milling of micron-SnO in a nitrogen atmosphere. A cation deficiency of 6.5% was found in the nano-SnO sample by X-ray photoelectron spectroscopy. After annealing at 350, 450, or 550℃ under dynamic vacuum conditions, oxygen vacancies were found in the nano-SnO samples, as verified by electron paramagnetic resonance experiments. The samples displayed weak ferromagnetism; that with both 6.5% Sn and at least 7.5% O vacancies showed the maximum saturation magnetization, reaching almost 1.7×10?3 emu/g at room temperature. The O vacancies tended to gather around Sn vacancies. An L-shaped defect model composed of one Sn and two O vacancies has been established, and its ferromagnetism has been calculated by a first-principles method. We found that the L-shaped defect induced a magnetic moment of 0.55 μB in the SnO lattice, the main contribution to which came from a spin-polarized electron in the p orbital of a corner Sn atom.
关键词： Magnetic,Nanocrystalline Stannous Oxide,Plasmonics,L-Shaped O-Sn-O Vacancies,Weak Ferromagnetism,Optical,Hybrid Materials
更新于2025-09-04 15:30:14
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All-Optical Poling and Two-Photon Absorption in Heterocyclic Azo Dyes with Different Side Groups
摘要： We investigated the optical properties of heterocyclic azo dyes with different side groups prepared: as powders, in PMMA matrix and side-chain polymers. We characterized the nonlinear optical effects of these compounds by Z-scan and all-optical poling techniques and supported these experiments with theoretical modeling. It was also found that these materials show strong two-photon absorption cross-sections exceeding 20 GM, which is one order of magnitude stronger than that of similar materials (azobenzene and p-aminoazobenzene). Our study reveals the dominant role of the side-chain system over the guest-host one and stress out the importance of the substituent in the efficiency of the poling process.
关键词： All-Optical Poling,Hybrid Materials,Heterocyclic Azo Dyes,Two-Photon Absorption,Plasmonics,Optical,Magnetic
更新于2025-09-04 15:30:14