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In situ synthesis of gold nanoparticles on pseudo-paper films as flexible SERS substrate for sensitive detection of surface organic residues
摘要： Surface enhanced Raman scattering (SERS) substrates that can be attached to rough, irregular surfaces and directly collect samples is especially useful for the detection of surface organic residues. Herein, novel AuNPs-pseudo-paper films (APPFs) with uniform structure, flexible properties and wicking capabilities were first fabricated and used as SERS substrate for the sensitive detection of surface pesticides residues. Gold nanoparticles (AuNPs) were in situ synthesized on pseudo-paper films (PPFs) by iterative seeding method to create lots of “hot-spots”, accordingly exhibiting high SERS activity (SERS enhancement factor of 3.02×106). By virtue of polyethylenimine (PEI) grafted onto the dissolved microcrystalline cellulose (MCC), AuCl4- and AuNPs can firmly be bonded to the surfaces of PPFs. The prepared APPFs show high reproducibility (relative standard deviation of 6.13 %), which is attributed to the uniform surface of the films. The fabricated APPFs SERS substrate allows rapid detection of surface pesticides residues by a facile “swabbing-measure” detection mode avoiding tedious and time-consuming sampling and separation processes. Based on their inherent SERS spectra, thiram, parathion methyl, and malachite green (MG) can be simultaneously detected on apple peel, which demonstrates the potential applicability of this developed protocol for surface organic residues analysis in agriculture and food security.
关键词： surface pesticides residues,pseudo-paper,in situ synthesis,SERS
更新于2025-09-23 15:23:52
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Selfa??Assembled PMMA Porous Membranes Decorated with In Situ Synthesized ZnO Nanoparticles with UVa??Tunable Wettability
摘要： This study reports a simple approach to fabricate porous poly(methyl methacrylate) (PMMA) membranes homogeneously decorated with exposed zinc oxide (ZnO) nanoparticles (NPs). This fabrication method significantly overcomes the disadvantages of both conventional foaming processes and incorporation of inorganic NPs in polymeric matrices. In particular, the porous structure is simply self-assembled by slowly evaporating a suitable solvent. The ZnO NPs are in situ formed by a thermally activated conversion of the zinc acetate precursor, previously embedded in the polymeric matrix. Scanning and transmission electron microscopy investigations show the formation of the desired self-assembled highly porous structure and ZnO NPs with branched morphology, respectively. The wetting behavior of the membranes surface is studied as a function of the ZnO content and UV irradiation, exploiting the switchable wettability of ZnO. The obtained unexpected results are then tentatively rationalized taking into account the surface chemistry and the roughness that arises from both porous structure and the different NPs dimensions and content.
关键词： porous membranes,nanocomposites,tunable wettability,self-assembly,in situ synthesis
更新于2025-09-23 15:21:01
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Resistive-type UVa??visible photodetector based on CdS NWs /ZnO nanowalls heterostructure fabricated using in-situ synthesis method
摘要： Here, the resistivity-type UV-visible photodetectors are designed and fabricated by implementation of direct integration between CdS nanowires(NWs) and vertical standing ZnO nanowalls with a facile in-situ synthesis method, in which ZnO nanowalls are employed as good support for anchoring well-dispersed CdS NWs to overcome its random distribution. The photodetectors based on CdS/ZnO heterojunctions demonstrate higher photo response activity than the prinstine CdS NWs and pure ZnO nanowalls photodetectors . The high performance could be attributed to the charge carrier separation efficiency and fast charge transportation facilitated by effective and close contact between CdS NWs and ZnO nanowalls. The results indicate that the ZnO/CdS heterojunctions fabricated by in-situ synthesis method provide a facile approach for nanoscale optoelectronic device.
关键词： photodetector,in-situ synthesis,CdS NWs,ZnO nanowalls
更新于2025-09-23 15:19:57
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Effect of Selective Laser Melting Process Parameters and Heat Treatment on Microstructure and Properties of Titanium Alloys Produced from Elemental Powders
摘要： This work investigates Selective Laser Melting (SLM) process as a method of in-situ synthesis of Ti-5Al and Ti-6Al-4V alloys using elemental powder mixture. Elemental spherical powders were used to prepare a powder mixture and the samples were produced by SLM process using different volume energy densities. The effects of volume energy density on the samples’ relative density, chemical composition, microstructure and microhardness before and after heat treatment have been studied. It was shown that volume energy density significantly effects the density and microstructure of Ti-5Al and Ti-6Al-4V alloys, as well as, the microhardness of obtained Ti-6Al-4V.
关键词： additive manufacturing,in-situ synthesis,titanium alloy,powder bed fusion,elemental powders
更新于2025-09-16 10:30:52
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Facile synthesis of durable perovskite quantum dots film with near unity photoluminescence quantum yield for efficient perovskite light emitting diode
摘要： In this work, a bright uniform PSK QDs film is synthesized in-situ using an amorphous polymer and optimizing the stoichiometry. The in-situ formed QDs film grown in the presence of poly(vinylpyrrolidone) chains shows a photoluminescence quantum yield (PLQY) as high as 98% even under low light intensities (0.01mW/cm2) with a long shelf lifetime of up to 2 years under ambient light (nanocrystals retain 100% of the initial PLQY). The near unity PLQY is due to the passivation of the surface defects of the PSK QDs by the Lewis base pyrrolidone groups of the polymer chain. Further, the QDs film shows higher thermal stability that increases by a factor of more than 5 compared to the bulk film. High efficient green perovskite light-emitting diodes (PLEDs) are fabricated without electron transporting layer using the high luminescent in situ synthesized low roughness QDs film with a current efficiency of 48.18 cd/A and power efficiency of 6.88 lm/W. Such devices start emitting green light at 2.5V and reach a maximum luminance of 124727 cd m?2 at 7V with external quantum efficiency of 10.5%. Further, the flexible PLED based on PSK QDs yields a maximum luminance of 43990 cd m-2 at 7V.
关键词： Perovskite quantum dots,perovskite light emitting diode,in situ synthesis
更新于2025-09-16 10:30:52